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1
Driver, Robert George. "Seismic behaviour of steel plate shear walls." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq21563.pdf.
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Alyami, Mahdi. "Seismic behaviour of gravity quay walls built on liquefiable soils." Thesis, University of Newcastle Upon Tyne, 2008. http://hdl.handle.net/10443/734.
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In the last 50 years there have been many documented failures of gravity retaining quay walls due to earthquake events. These failures are often associated with significant deformation of liquefiable soil deposits (e. g. major damage occurred at Kobe Port during the 1995 Hyogoken-Nanbu earthquake). Saudi Arabia has similar types of quay walls located in regions that have the potential to experience significant seismic events. These walls have not been designed for seismic resistance and therefore have the potential to suffer serious damage from seismic activity. For many years the design of seismic gravity quay walls has been studied and design codes for engineering practice established; however, the widespread failures of these structures during recent earthquakes demonstrates that these design methods may be insufficient. Such gravity quay wall failures have stimulated progress in the development of a performance-based seismic design method using non-linear inelastic dynamic analysis for quay wall structures. The aim of this study was to develop a methodology for the seismic design of gravity quay walls using a non-linear elasto-plastic dynamic analysis. The final method adopted in this work is based on the generalised elasto-plasiticity constitutive model developed by Pastor et aL (1990), with some minor modifications, which has been incorporated into a finite element procedure. The proposed P-Z sand model was first validated by simulating published monotonic and cyclic test results. Secondly, an effective stress analysis was established by developing a finite element model for Kobe Port Island quay walls using the P-Z sand model. This model was validated by comparing the predicted deformations with those experienced at Kobe. The computed residual deformations from the analysis were in good agreement with published field observations. To develop mitigation strategies, a parametric study of the seismic perfonnance of gravity quay walls, using the effective stress analysis, was conducted. This study assessed the effect of various structural and geotechnical parameters on the seismic performance of quay walls. Twenty-six cases of effective stress analysis with variation in tidal range, soil permeability, soil relative densities, and wall widths were conducted as well as analyses to test the importance of considering multi-directional seismic excitations as opposed to uni-directional. In order to assess the safety of existing quay walls in Jeddah Port, an experimental programme was conducted. This programme consisted of a site investigation (using a standard penetration test (SPT)) to determine the in situ relative density of the existing backfill, a series of laboratory based, monotonic and cyclic triaxial tests (to define the soil properties of Jeddah Port sand) and a two-dimensional effective stress finite element analysis of a typical Jeddah quay wall. The monotonic and cyclic triaxial tests were conducted for three different relative densities of D, = 35 %, 55% and 75%. These represent loose (equal to in situ conditions as established by the site investigation), medium dense and dense sand. The experimental results are discussed and then used to identify the P-Z sand model parameters. These parameters were used in conjunction with a finite element analysis of Jeddah Port quay walls to Predict the seismic deformations. In this analysis the finite element model was subjected to a number of different ground motions, which represented two different levels of earthquake intensity; namely moderate and strong ground shaking. The effect of improvement strategies such as increasing the relative density of the backfill and foundation materials was then assessed The results of the simulations showed that existing Jeddah Port quay walls are not satisfactory to resist either moderate or strong earthquake excitations. However, if the relative density is increased to 55% then satisfactory performance can be achieved for a moderate intensity earthquake. For the case of strong shaking, the analysis showed that the quay walls did not demonstrate the required performance levels; however, they were only under specification by 10%. Finally, a flowchart illustrating a seismic design procedure for gravity quay walls has been proposed, which is applicable to both existing and new gravity quay walls. Key-words: quay wall, liquefaction, earthquake, port, effective stress, constitutive model.
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Lopes, Mario Manuel Paisana dos Santos. "Seismic behaviour of reinforced concrete walls with low shear ratio." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/8058.
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Neelakantan, G. "Seismic behavior of tiedback retaining walls." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185528.
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Tied-back retaining walls frequently fail during earthquakes. Such failures are usually characterized by large displacements of the retaining wall and subsidence of the backfill. Often these failures result in extensive damage to the tied-back wall system and to adjoining structures and lifeline facilities. Whereas the seismic behavior of gravity retaining walls has been investigated in detail and procedures are now available for the seismic design of gravity retaining walls, very little analytical or experimental work has been reported on the behavior of tied-back retaining walls when they are subjected to seismic loads. In this research, a limit equilibrium method is used to analyze the seismic behavior of tied-back retaining walls. The analytical approach is calibrated against results from shake table tests on aluminium walls retaining a dry cohesionless soil. The shake table experiments were performed at the State University of New York at Buffalo seismic simulator facility. The analytical and the experimental study indicate the tremendous influence of anchorage systems on the performance of tied-back retaining walls during earthquakes. Based on the results of these studies, a procedure is proposed for the design of tied-back retaining walls in seismically active regions. The main thrust of the proposed seismic design procedure is in improving the anchorage capacity of tied-back retaining walls.
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Rezai, Mahmoud. "Seismic behaviour of steel plate shear walls by shake table testing." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0028/NQ38963.pdf.
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Gjata, Marjus. "Seismic Behavior of Dowel Type Precast Panel-Foundation Connection." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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Precast concrete panels are a popular construction technique due to their increased construction speed, low cost and the ability to use the precast concrete elements for structural walls to provide high strength and stiffness when used for structural purposes. Slender precast concrete wall panels are a common construction method for single storey warehouse type buildings.
Following the Canterbury earthquake sequence Christchurch from 2010 – 2014, damage was observed in precast concrete wall buildings that resulted in out-of-plane collapse of wall panels. . This project seeks to investigate the behaviour of precast reinforced concrete walls designed for limited ductility under gravity and quasi-static in-plane loading. The main point of interest in this thesis research is to understand the seismic behaviour of the connection as well as the out-of-plane stability of slender panels.
To investigate the behaviour of this panel and connection type, three slender precast concrete walls, representing full scale panel geometry were subjected to quasi-static cyclic loading. Two common panel to foundation connection types were studied: 1) threaded inserts and 2) traditional starter bars as well as one alternative connection which was developed as a means to improve the out-of-plane response and understand the impact of this design choice on the in-plane behavior of the wall.
For all the three units, the dowel connection performed well and the thin wall failed under flexural failure due to loss of strength cause by fracturing of longitudinal rebars after being buckled under the effects of lateral cyclic loading. Significant horizontal cracking occurred on each of the tests at dowel level except unit threaded insert with 50mm cover behind the head of the insert (TI12-C50-IP) which suffered a secondary horizontal crack at 500mm above the main crack and a diagonal crack at the center of the wall. Moreover, this unit was able to undergo more deformation due to a secondary crack.
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Maleki, Ahmad. "Improving seismic behaviour of steel plate shear walls with and without cut-outs." Thesis, Kingston University, 2012. http://eprints.kingston.ac.uk/25604/.
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In this work experimental and numerical investigations were conducted on seismic behaviour of steel plate shear wall systems (SPSW) with and without cut-outs. Medium-scale specimens with moment-resisting connections between beam and columns and specific edge connections for fish plates were designed and constructed. The specimens were subjected to the cyclic quasi-static load. A loading system and proper lateral bracing unit was designed and built to apply the loading history according to ATC-24 protocol. Nonlinear finite element analysis models with dynamic formulation were developed to analyse test specimens. The results were validated with available published test results from other researchers. After validation, the model was used for estimating the maximum load required for testing of specimens. The efficiency of the method was finally proved by comparing the pushover and hysteresis analysis results with tests carried out in Kingston University's lab. The test series comprised frame-only, steel plate shear wall with two different types of steel plate and corresponding specimens with circular cut-outs in the steel plates, GFRP-steel Sandwich Shear Walls (GSSW) with different GFRP lay-up, GSSW with cut-outs and finally the steel plate shear wall with cut-out and optimally designed steel stiffeners, The specification of boundary members and the type of connections was kept unchanged in all specimens. The effectiveness of utilising the GFRP plies and steel stiffeners for improving the seismic performance of steel plate shear walls with and without cut-outs was explored. The effectiveness of these methods for enhancing the initial stiffness and ultimate load capacity of specimens with no noticeable requirements for increasing flexural stiffness for columns was verified.
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Jackson, Perry Francis. "An investigation into the deformation behaviour of geosynthetic reinforced soil walls under seismic loading." Thesis, University of Canterbury. Department of Civil and Natural Resources Engineering, 2010. http://hdl.handle.net/10092/5522.
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Reinforcement of soil enables a soil slope or wall to be retained at angles steeper than the soil material’s angle of repose. Geosynthetic Reinforced Soil (GRS) systems enable shortened construction time, lower cost, increased seismic performance and potentially improve aesthetic benefits over their conventional retaining wall counterparts such as gravity and cantilever type retaining walls. Experience in previous earthquakes such as Northridge (1994), Kobe (1995), and Ji-Ji (1999) indicate good performance of reinforced soil retaining walls under high seismic loads. However, this good performance is not necessarily due to advanced understanding of their behaviour, rather this highlights the inherent stability of reinforced soil against high seismic loads and conservatism in static design practices.
This is an experimental study on a series of seven reduced-scale GRS model walls with FHR facing under seismic excitation conducted using a shake-table. The models were 900 mm high, reinforced by five layers of stiff Microgrid reinforcement, and were founded on a rigid foundation. The soil deposit backfill was constructed of dry dense Albany sand, compacted by vibration (average Dr = 90%). The influence of the L/H ratio and wall inclination on seismic performance was investigated by varying these important design parameters throughout the testing programme. The L/H ratio ranged from 0.6 – 0.9, and the walls were primarily vertical except for one test inclined at 70o to the horizontal.
During testing, facing displacements and accelerations within the backfill were recorded at varying levels of shaking intensity. Mechanisms of deformation, in particular, were of interest in this study. Global and local deformations within the backfill were investigated using two methods. The first utilised coloured horizontal and vertical sand markers placed within the backfill. The second utilised high-speed camera imaging for subsequent analysis using Geotechnical Particle Image Velocimetry (GeoPIV) software. GeoPIV enabled shear strains to be identified within the soil at far smaller strain levels than that rendered visible by eye using the coloured sand markers. The complementary methods allowed the complete spatial and temporal development of deformation within the backfill to be visualised.
Failure was predominantly by overturning, with some small sliding component. All models displayed a characteristic bi-linear displacement-acceleration curve, with the existence of a critical acceleration, below which deformations were minor, and above which ultimate failure occurs. During failure, the rate of sliding increased significantly.
An increase in the L/H ratio from 0.6 to 0.9 caused the displacement-acceleration curve to be shallower, and hence the wall to deform less at low levels of acceleration. Accelerations at failure also increased, from 0.5g to 0.7g, respectively. A similar trend of increased seismic performance was observed for the wall inclined at 70o to the horizontal, when compared to the other vertical walls.
Overturning was accompanied by the progressive development of multiple inclined shear surfaces from the wall crest to the back of the reinforced soil block. Failure of the models occurred when an inclined failure surface developed from the lowest layer of reinforcement to the wall crest. Deformations largely confirmed the two-wedge failure mechanism proposed by Horii et al. (2004).
For all tests, the reinforced soil block was observed to demonstrate non-rigid behaviour, with simple shearing along horizontal planes as well as strain localisations at the reinforcement or within the back of the reinforced soil block. This observation is contrary to design, which assumes the reinforced soil block to behave rigidly.
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Samayoa, Avalos Julio Alfredo. "Semi-engineered earthquake-resistant structures: one-storey buildings built up with gabion-box walls." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/11121/.
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This thesis studies the static and seismic behavior of simple structures made with gabion box walls. The analysis was performed considering a one-story building with standard dimensions in plan (6m x 5m) and a lightweight timber roof.
The main focus of the present investigation is to find the principals aspects of the seismic behavior of a one story building made with gabion box walls, in order to prevent a failure due to seismic actions and in this way help to reduce the seismic risk of developing countries where this natural disaster have a significant intensity.
Regarding the gabion box wall, it has been performed some calculations and analysis in order to understand the static and dynamic behavior. From the static point of view, it has been performed a verification of the normal stress computing the normal stress that arrives at the base of the gabion wall and the corresponding capacity of the ground.
Moreover, regarding the seismic analysis, it has been studied the in-plane and out-of-plane behavior. The most critical aspect was discovered to be the out-of-plane behavior, for which have been developed models considering the “rigid- no tension model” for masonry, finding a kinematically admissible multiplier that will create a collapse mechanism for the structure.
Furthermore, it has been performed a FEM and DEM models to find the maximum displacement at the center of the wall, maximum tension stresses needed for calculating the steel connectors for joining consecutive gabions and the dimensions (length of the wall and distance between orthogonal walls or buttresses) of a geometrical configuration for the standard modulus of the structure, in order to ensure an adequate safety margin for earthquakes with a PGA around 0.4-0.5g.
Using the results obtained before, it has been created some rules of thumb, that have to be satisfy in order to ensure a good behavior of these structure.
10
Aaleti, Sriram R. "Behavior of rectangular concrete walls subjected to simulated seismic loading." [Ames, Iowa : Iowa State University], 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3389080.
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Mohammed, Anwer Sabah Mohammed. "Seismic Behavior of Screen Grid Core Insulated Concrete Form Walls." PDXScholar, 2019. https://pdxscholar.library.pdx.edu/open_access_etds/4810.
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The use of the insulated concrete form (ICF) walls in residential buildings has increased over the past few decades. Much research has been conducted to evaluate the lateral strength of these walls by applying monotonic and cyclic loadings. In the current study, full-scale shake table experiments were employed to evaluate the in-plane behavior of four screen grid insulated concrete form (SGICF) walls. The first two wall specimens utilized dry fit insulated form blocks made from recycled expanded polystyrene granules that were bonded together with cement. When stacked, the cavities in the blocks formed a grid of cores that are evenly spaced vertically and horizontally. The walls consisted of four circular vertical cores and five circular horizontal cores reinforced with a single rebar placed nominally in the center of each core. The rest of the wall specimens were newly suggested pattern of SGICF walls, which consisted of three circular vertical cores and five circular horizontal cores. Two rebars were placed in each vertical core, and a single rebar was placed nominally in the center of each horizontal core.
Each wall was built on top of a foundation block that was designed such that failure would occur within the walls themselves. For each type of SGICF walls, steel fiber-reinforced concrete was used in one of the walls to evaluate the effect on failure modes, drift capacity, and shear strength. The results showed that the use of fiber-reinforced concrete in the cores of the SGICF walls that were built out of ICF blocks had not significantly improved the drift capacity, and had exhibited lower strengths than the wall with conventional concrete. These outcomes were mainly attributed to voids in the cores that had resulted despite similarities in workability of the concrete mixes and in techniques used to place the concrete in the walls. On the other hand, the use of the steel fiber-reinforced concrete in the cores of the newly suggested pattern of SGICF wall and the two rebars in the vertical cores had improved the drift ductility of the wall by about 63%.
The evaluation of the steel fiber-concrete was conducted at the component levels of the SGICF walls. Six simply supported reinforced concrete beams (3 ft. long) were tested in a three-point bending configuration by applying a cyclic loading protocol. Results showed that the steel fiber-concrete did not improve the lateral strength and the drift capacity. Steel fiber dose played an essential role in this investigation.
Analytical approaches were used to estimate the initial stiffness and the lateral strength of the SGICF walls. None of the approaches managed to provide an acceptable estimation of the initial stiffness. Meanwhile, the summation of individual vertical core plastic moment capacity and the ACI equation for the minimum shear strength of the concrete methods were successful in estimating the in-plane lateral strengths. Finally, a computer model was created to predict the lateral in-plane behavior of the SGICF walls. Results showed that the computer model provided good estimations for the peak lateral strength and the initial stiffness.
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Guo, XuHua. "EFFECTS OF COLUMN STIFFNESS ON SEISMIC BEHAVIOR OF STEEL PLATE SHEAR WALLS." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/639.
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Steel plate shear walls (SPSWs) are a lateral force resisting system consisting of thin infill steel plates surrounded by boundary frame members. The infill steel plates are allowed to buckle in shear and subsequently form diagonal tension field actions during earthquake events. Hysteretic energy dissipation of this system is primarily achieved through yielding of the infill plates. Conceptually, in a SPSW system with ideally rigid columns pinned to ground, the infill plates at different stories will yield simultaneously as a result of the lateral loads. However, when the columns become flexible, infill plate yielding may initially occur at one story and progressively spread into the other stories with increasing roof displacement.
This research investigates the effect of column stiffness on infill plate yielding sequence and distribution along the height of steel plate shear walls subjected to earthquake forces. Analytical models are derived and validated for two-story SPSWs. Based on the derived model, probabilistic simulations are conducted to calculate the probability of achieving infill plate yielding in both stories before occurrence of a premature failure caused by excessive inter story drift at the initially yielded story. A total of three simulation methods including the Monte-Carlo method, the Latin Hypercube sampling method, and the Rosenblueth’s 2K+1 point estimate method were considered to account for the uncertain infill plate thickness and lateral force distributions in the system.The investigation is also extended to multi-story SPSWs. Three example six-story SPSWs are evaluated using the Rosenblueth's 2K+1 point estimation method which is identified to be most efficient from the simulation on two-story SPSWs. Moreover, the effectiveness of the column minimum moment of inertia required in the current code for achieving infill plate yielding at every story of SPSWs is evaluated.
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Yuksel, Bahadir S. "Experimental Investigation Of The Seismic Behavior Of Panel Buildings." Phd thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/2/1070309/index.pdf.
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Shear-wall dominant multi-story reinforced concrete structures, constructed by using a special tunnel form technique are commonly built in countries facing a substantial seismic risk, such as Chile, Japan, Italy and Turkey. In 1999, two severe urban earthquakes struck Kocaeli and Düzce provinces in Turkey with magnitudes (Mw) 7.4 and 7.1, respectively. These catastrophes caused substantial structural damage, casualties and loss of lives. In the aftermath of these destructive earthquakes, neither demolished nor damaged shear-wall dominant buildings constructed by tunnel form techniques were reported. In spite of their high resistance to earthquake excitations, current seismic code provisions including the Uniform Building Code and the Turkish Seismic Code present limited information for their design criteria. This study presents experimental investigation of the panel unit having H-geometry. To investigate the seismic behavior of panel buildings, two prototype test specimens which have H wall design were tested at the Structural Mechanics Laboratory at METU. The experimental work involves the testing of two four-story, 1/5-scale reinforced concrete panel form building test specimens under lateral reversed loading, simulating the seismic forces and free vibration tests. Free vibration tests before and after cracking were done to assess the differences between the dynamic properties of uncracked and cracked test specimens. A moment-curvature program named Waller2002 for shear walls is developed to include the effects of steel strain hardening, confinement of concrete and tension strength of concrete. The moment-curvature relationships of panel form test specimens showed that walls with very low longitudinal steel ratios exhibit a brittle flexural failure with very little energy absorption. Shear walls of panel form test specimens have a reinforcement ratio of 0.0015 in the longitudinal and vertical directions. Under gradually increasing reversed lateral loading, the test specimens reached ultimate strength, as soon as the concrete cracked, followed by yielding and then rupturing of the longitudinal steel. The displacement ductility of the panel form test specimens was found to be very low. Thus, the occurrence of rupture of the longitudinal steel, as also observed in analytical studies, has been experimentally verified. Strength, stiffness, energy dissipation and story drifts of the test specimens were examined by evaluating the test results.
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Koppal, Manasa. "Computational Investigation of Tunable Steel Plate Shear Walls for Improved Seismic Resistance." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/34570.
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Steel plate shear walls (SPSWs) are popular lateral force resisting systems whose practical applications range from high seismic regions to medium and low seismic areas and wind load applications. The factors which make SPSW attractive include its energy dissipation capacity, excellent ductility, constructability, speed of construction compared to concrete shear walls, reduced architectural footprint compared to concrete shear walls, and increased inelastic deformation capacity as compared to braced frames. The principle behind current SPSW design is that the post-buckling tension field capacity of the thin web plate is proportioned to resist the full lateral load. The resulting web plate is typically quite thin, buckles at low loads, possesses low stiffness, and does not provide resistance when the lateral loads are reversed until the tension field engages in the opposite direction. To compensate for these shortcomings, moment connections are required at the beam to column connections to improve energy dissipation, increase stiffness, and provide lateral resistance during load reversal. The resulting SPSW designs with very thin web plates, moment connections, and beams and columns significantly larger than comparable braced frames, can result in inefficient structural systems.
The objective of this work is to develop steel plate shear wall systems that are more economic and efficient. In order to achieve this, approaches like shear connections between beams and columns, allowing some yielding in columns and increasing plate thicknesses were attempted. But these approaches were not effective in that there was no reduction in the amount of steel required since stiffness controlled the designs. This necessitated the creation of tunable steel plate shear wall systems in which strength and stiffness could be decoupled. Preliminary analyses of seven steel plate shear wall systems which allow tunability were conducted and two configurations namely circular holes and butterfly shaped links around the perimeter, that showed promising results were chosen. The solid plate in the middle of the panel contributes significant pre-yield stiffness to the system while the geometry of the perimeter perforations controls strength and ductility. An example panel was designed using the two approaches and compared to panels designed using current SPSW design methods. The proposed configurations resulted in improved overall performance of the system in terms of energy dissipation, stable hysteresis, required less steel and no moment connections between beams and columns. This was also observed from the parametric study that was performed by varying the thickness of the web plate and the geometry of the configurations. Thus it was concluded that the two proposed configurations of cutouts were promising concepts that allow separate tuning of the system strength, stiffness and ductility and could be adopted in any seismic zone for improved seismic resistance.Master of Science
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Le, Roux Rudolf Cornelis. "Assessment of seismic drift of structural walls designed according to SANS 10160 - Part 4." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/5282.
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Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: Reinforced concrete structures, designed according to proper capacity design guidelines, can deform inelastically without loss of strength. Therefore, such structures need not be designed for full elastic seismic demand, but could be designed for a reduced demand. In codified design procedures this reduced demand is obtained by dividing the full elastic seismic demand by a code-defined behaviour factor. There is however not any consensus in the international community regarding the appropriate value to be assigned to the behaviour factor. This is evident in the wide range of behaviour factor values specified by international design codes. The purpose of this study is to assess the seismic drift of reinforced concrete structural walls in order to evaluate the current value of the behaviour factor prescribed by SANS 10160-4 (2009). This is done by comparing displacement demand to displacement capacity for a series of structural walls. Displacement demand is calculated according to equivalency principles (equal displacement principle and equal energy principle) and verified by means of a series of inelastic time history analyses (ITHA). In the application of the equivalency rules the fundamental periods of the structural walls were based on cracked sectional stiffness from moment-curvature analyses. Displacement capacity is defined by seismic design codes in terms of inter storey drift limits, with the purpose of preventing non-structural damage in building structures. In this study both the displacement demand and displacement capacity were converted to ductility to enable comparison. The first step in seismic force-based design is the estimation of the fundamental period of the structure. The influence of this first crucial step is investigated in this study by considering two period estimation methods. Firstly, the fundamental period may be calculated from an equation provided by the design code which depends on the height of the building. This equation is known to overestimate acceleration demand, and underestimate displacement demand. The second period estimation method involves an iterative procedure where the stiffness of the structure is based on the cracked sectional stiffness obtained from moment-curvature analysis. This method provides a more realistic estimate of the fundamental period of structures, but due to its iterative nature it is not often applied in design practice. It was found that, regardless of the design method, the current behaviour factor value prescribed in SANS 10160-4 (2010) is adequate to ensure that inter storey drift of structural walls would not exceed code-defined drift limits. Negligible difference between the equivalency principles and ITHA was observed.
AFRIKAANSE OPSOMMING: Gewapende beton strukture wat ontwerp is volgens goeie kapasiteitsontwerp-riglyne kan plasties vervorm sonder verlies aan sterkte. Gevolglik hoef hierdie strukture nie vir die volle elastiese seismiese aanvraag ontwerp te word nie, maar kan vir 'n verminderde aanvraag ontwerp word. In gekodifiseerde ontwerpriglyne word so 'n verminderde aanvraag verkry deur die volle elastiese aanvraag te deel deur 'n kode-gedefinieerde gedragsfaktor. Wat egter duidelik blyk uit die wye reeks van gedragsfaktor waardes in internasionale ontwerp kodes, is dat daar geen konsensus bestaan in die internasionale gemeenskap met betrekking tot die geskikte waarde van die gedragsfaktor nie. Die doel van hierdie studie is om seismiese verplasing van gewapende beton skuifmure te evalueer ten einde die waarde van die gedragsfaktor wat tans deur SANS 10160-4 (2009) voorgeskryf word te assesseer. Dit word gedoen deur verplasingsaanvraag te vergelyk met verplasingskapasiteit. In hierdie studie word verplasingsaanvraag bereken deur middel van gelykheidsbeginsels (gelyke verplasingsbeginsel en gelyke energiebeginsel) en bevestig deur middel van nie-elastiese tydsgeskiedenis analises (NTGA). Die effek van versagting as gevolg van nie-elastiese gedrag word in aanmerking geneem in die toepassing van die gelykheidsbeginsels. Verplasingskapasiteit word deur seismiese ontwerpkodes gedefinieer deur perke te stel op die relatiewe laterale beweging tussen verdiepings, met die doel om nie-strukturele skade te verhoed. Om verplasingsaanvraag en -kapasiteit te vergelyk in hierdie studie, word beide omgeskakel na verplasingsduktiliteit. Die eerste stap in kraggebaseerde seismiese ontwerp is om die fundamentele periode te beraam. Die invloed van hierdie eerste kritiese stap word in hierdie studie aangespreek deur twee periodeberamingsmetodes te ondersoek. Eerstens kan die fundamentele periode bereken word deur 'n vergelyking wat 'n funksie is van die hoogte van die gebou. Dit is egter algemeen bekend dat hierdie vergelyking versnellingsaanvraag oorskat en verplasingsaanvraag onderskat. Die tweede metode behels 'n iteratiewe prosedure waar die styfheid van die struktuur gebaseer word op die gekraakte snit eienskappe, verkry vanaf 'n moment-krommingsanalise. 'n Beter beraming van die fundamentele periode word verkry deur hierdie metode, maar as gevolg van die iteratiewe aard van die metode word dit selde toegepas in ontwerppraktyk. Die resultate van hierdie studie toon dat die huidige waarde van die gedragfaktor soos voorgeskryf in SANS 10160-4 (2010) geskik is om te verseker dat die relatiewe laterale beweging tussen verdiepings binne kode-gedefinieerde perke sal bly. Onbeduidende verskil is waargeneem tussen die resultate van gelykheidsbeginsels en NTGA.
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Kessler, Samantha. "A study of the seismic response modification factor for log shear walls." Thesis, Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/3909.
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Yildiz, Ersan. "A Numerical Study On The Dynamic Behaviour Of Gravity And Cantilever Retaining Walls With Granular Backfill." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12608145/index.pdf.
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Dynamic behaviour of gravity and cantilever retaining walls is investigated by finite element method, incorporating the nonlinear elasto-plastic material properties of soil and seperation of the wall and backfill. Two dimensional finite
element models are developed employing the finite element software ANSYS. The wall is modelled to rest on a soil layer allowing translational and rotational movements of the wall. Soil-wall systems are subjected to harmonic and real earthquake motions with different magnitude and frequency characteristics at the base. The maximum lateral force and its application point durinG dynamic loading are determined for each case. It is observed that the frequency content of the base motion has a significant influence on the dynamic lateral soil pressures and the lateral forces considerably increase as the base motion frequency approaches the fundamental frequency of the soil layer. The maximum lateral thrusts calculated by finite element analyses are generally found to be greater than those suggested by Mononobe-Okabe method and experimental findings. Nevertheless, the locations of the application point obtained by finite element method are found to be in good agreement with the results of experimental studies.
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Spathelf, Christian Alexander. "Assessment of the behaviour factor for the seismic design of reinforced concrete structural walls according to SANS 10160 : part 4." Thesis, Link to the online version, 2008. http://hdl.handle.net/10019/2039.
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De, Bonis Antonio. "The influence of infill walls on seismic behavior of a historical building in Shanghai." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016.
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Seismic assessment and seismic strengthening are the key issues need to be figured out during the process of protection and reusing of historical buildings.
In this thesis the seismic behaviors of the hinged steel structure, a typical structure of historical buildings, i.e. hinged steel frames in Shanghai, China, were studied based on experimental investigations and theoretic analysis. How the non-structural
members worked with the steel frames was analyzed thoroughly.
Firstly, two 1/4 scale hinged steel frames were constructed based on the structural system of Bund 18, a historical building in Shanghai: M1 model without infill walls, M2 model with infill walls, and tested under the horizontal cyclic loads to investigate their seismic behavior.
The Shaking Table Test and its results indicated that the seismic behavior of the hinged steel frames could be improved significantly with the help of non-structural members, i.e., surrounding elements outside the hinged steel frames and infilled walls.
To specify, the columns are covered with bricks, they consist of I shape formed steel sections and steel plates, which are clenched together. The steel beams are connected to the steel column by steel angle, thus the structure should be considered as a hinged
frame.
And the infilled wall acted as a compression diagonal strut to withstand the horizontal load, therefore, the seismic capacity and stiffness of the hinged steel frames with infilled walls could be estimated by using the equivalent compression diagonal strut
model. A SAP model has been constructed with the objective to perform a dynamic nonlinear analysis. The obtained results were compared with the results obtained from Shaking Table Test. The Test Results have validated that the influence of infill walls
on seismic behavior can be estimated by using the equivalent diagonal strut model.
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Egorova, Natalia Vadimovna. "Experimental Study of Ring-Shaped Steel Plate Shear Walls." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/52633.
Full textAbstract:
A new type of steel plate shear wall has been devised which resists out-of-plane buckling without requiring stiffeners. The ring-shaped steel plate shear wall (RS-SPSW) includes a web plate that is cut with a pattern of holes leaving ring-shaped portions of steel connected by diagonal links. The ring shape resists out-of-plane buckling through the mechanics of how a circular ring deforms into an ellipse. It has been shown that the ring's compression diagonal will shorten a similar amount as the tension diagonal elongates, essentially eliminating the slack in the direction perpendicular to the tension field. Because of the unique features of the ring's mode of distortion, the load-deformation response of the resulting RS-SPSW system can exhibit full hysteretic behavior and possess greatly improved stiffness relative to thin unstiffened SPSW. The concept has been validated through testing on seven 34 in x 34 in panels. General conclusions about influence of different geometric parameters on plate behavior have been made.Master of Science
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Silveira, Dora Susana Gomes da. "Constructive and mechanical characterisation of adobe masonry walls of existing buildings." Doctoral thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/17313.
Full textAbstract:
Doutoramento em Engenharia CivilEarthen construction has been widely used throughout the world, since approximately 10000 years ago and until the present day. A significant part of the world earthen built heritage – including many properties inscribed on the UNESCO’s World Heritage List –, however, is at risk. In Portugal, earth was also a widely used construction material until the middle of the 20th century. In Aveiro district, in particular, adobe construction was very common. Currently, there are still a great number of adobe constructions in this region, a large part of which are in use. Many of the existing buildings are of social, cultural, and architectural value. Despite their value, however, many of these buildings are in a poor state of conservation, suffering from various structural and non-structural defects. The problems observed in existing adobe buildings result in large part from a lack of knowledge regarding the materials and building systems used in this type of construction. There is, in particular, a lack of knowledge about the properties and behaviour of adobe masonry walls, which are key structural elements that influence the overall behaviour of buildings. The main aim of the research developed and discussed in this thesis is thus to contribute to this knowledge, focusing, in particular, on the adobe buildings of Aveiro district. For this purpose, a visual and dimensional inspection of the facade walls of twenty-one representative adobe buildings was conducted. With this inspection, it was possible to carry out a detailed analysis of the facade walls – including their structural system, coatings, and traditional masonry materials – and to assess the vulnerabilities, common defects, and state of conservation of these elements. A series of experimental tests were also carried out. Simple compression tests were performed on cylindrical and cubic adobe specimens, flexural tests on adobe bricks, and splitting tests on cylindrical specimens. Simple compression and diagonal compression tests were also conducted on ten full-scale adobe masonry wall panels, built with adobes taken from an existing construction. Finally, an in-plane horizontal cyclic test was performed on a full-scale double-T shaped adobe wall, also built with adobes from an existing construction. With the tests carried out, it was possible to characterise the strength, stiffness, stress-strain relationships, and common damage pattern of the test specimens, and to assess correlations between different mechanical properties. It was also possible to develop a comparison between the strength values obtained and the limits indicated in existing standards for earthen construction, and between the results obtained and those determined by other authors for test specimens representative of adobe construction in other countries. The results presented and discussed in this thesis contribute to the enrichment of knowledge that is considered essential to support the conservation and rehabilitation of existing adobe buildings, not only in Portugal, but also in other regions of the world.
A construção em terra tem sido muito utilizada em todo o mundo, desde há cerca de 10000 anos atrás e até aos dias de hoje. Uma parte significativa do património mundial construído com terra, incluindo vários bens inscritos na Lista de Património Mundial da UNESCO, encontra-se, no entanto, em risco. Em Portugal, a terra foi também um material de construção muito utilizado até meados do século XX. No distrito de Aveiro, em particular, a construção em adobe era muito comum. Atualmente, existe ainda um elevado número de construções em adobe nesta região, grande parte das quais se encontram em uso. Muitos dos edifícios existentes são de valor social, cultural e arquitetónico reconhecido. No entanto, apesar do seu valor, muitos destes edifícios estão em mau estado de conservação, apresentando anomalias estruturais e não estruturais variadas. Os problemas observados nos edifícios existentes de adobe resultam, em grande parte, de falta de conhecimento sobre os materiais e sistemas de construção utilizados neste tipo de edificação. Há, em particular, falta de conhecimento sobre as propriedades e o comportamento das paredes de alvenaria de adobe, que são elementos estruturais principais que influenciam o comportamento global dos edifícios. Assim, o trabalho de investigação desenvolvido e discutido nesta tese tem como principal objetivo contribuir para este conhecimento, debruçando-se, em particular, sobre as construções em adobe do distrito de Aveiro. Para este efeito, foi realizada uma inspeção visual e dimensional das paredes de fachada de vinte e um edifícios de adobe representativos. Com esta inspeção, foi possível analisar de forma detalhada as paredes de fachada – incluindo o seu sistema estrutural, revestimentos e materiais de alvenaria tradicionais – e avaliar as vulnerabilidades, anomalias comuns e estado de conservação destes elementos. Uma série de ensaios experimentais foi também levada a cabo. Foram realizados ensaios de compressão simples sobre provetes cilíndricos e cúbicos de adobe, ensaios de flexão sobre blocos de adobe e ensaios de compressão diametral sobre provetes cilíndricos. Foram ainda realizados ensaios de compressão simples e compressão diagonal sobre dez painéis de alvenaria de adobe à escala real, construídos com adobes recolhidos de uma construção existente. Por fim, realizou-se o ensaio de uma parede à escala real em forma de ‘duplo T’, construída também com adobes de uma construção existente, sob a ação de uma carga horizontal cíclica, aplicada no plano da parede. Com os ensaios realizados, foi possível caracterizar a resistência, a rigidez, as relações de comportamento tensão-deformação e o padrão comum de dano dos elementos ensaiados, e avaliar as correlações entre diferentes propriedades mecânicas. Foi ainda desenvolvida uma comparação entre os valores de resistência obtidos e os limites indicados nas normas existentes para a construção em terra, bem como entre os resultados obtidos e aqueles determinados por outros autores para a alvenaria de adobe representativa da construção em adobe noutros países. Os resultados apresentados e discutidos nesta tese contribuem para o enriquecimento de conhecimento que é considerado essencial para apoiar a conservação e reabilitação dos edifícios de adobe existentes, não só em Portugal, mas também noutras regiões do mundo.
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Hassan, Mohamed. "INELASTIC DYNAMIC BEHAVIOR AND DESIGN OF HYBRID COUPLED WALL SYSTEMS." Doctoral diss., University of Central Florida, 2004. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4437.
Full textAbstract:
A key consideration in seismic design of buildings is to ensure that the lateral load resisting system has an appropriate combination of strength, stiffness and energy dissipation capacity. Hybrid coupled wall systems, in which steel beams are used to couple two or more reinforced concrete shear walls in series, can be designed to have these attributes and therefore have the potential to deliver good performance under severe seismic loading. This research presents an investigation of the seismic behavior of this type of structural system. System response of 12- and 18-story high prototypes is studied using transient finite element analyses that accounts for the most important aspects of material nonlinear behavior including concrete cracking, tension stiffening, and compressive behavior for both confined and unconfined concrete as well as steel yielding. The developed finite element models are calibrated using more detailed models developed in previous research and are validated through numerous comparisons with test results of reinforced concrete walls and wall-beam subassemblages. Suites of transient inelastic analyses are conducted to investigate pertinent parameters including hazard level, earthquake record scaling, dynamic base shear magnification, interstory drift, shear distortion, coupling beam plastic rotation, and wall rotation. Different performance measures are proposed to judge and compare the behavior of the various systems. The analyses show that, in general, hybrid coupled walls are particularly well suited for use in regions of high seismic risk. The results of the dynamic analyses are used to judge the validity of and to refine a previously proposed design method based on the capacity design concept and the assumption of behavior dominated by the first vibration mode. The adequacy of design based on the pushover analysis procedure as promoted in FEMA-356 (2000) is also investigated using the dynamic analysis results. Substantial discrepancies between both methods are observed, especially in the case of the 18-story system. A critical assessment of dynamic base shear magnification is also conducted, and a new method for estimating its effects is suggested. The method is based on a modal combination procedure that accounts for presence of a plastic hinge at the wall base. Finally, the validity of limitations in FEMA-368 (2000) on building height, particularly for hybrid coupled wall systems, is discussed.Ph.D.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil and Environmental Engineering
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Rodríguez, Aguirre Anita Pamela. "Estudio comparativo del comportamiento sísmico de una edificación reforzada con muros de concreto armado y con disipadores de fluido viscoso." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2020. http://hdl.handle.net/10757/652500.
Full textAbstract:
La presente tesis, está enfocada al estudio del comportamiento sísmico comparativo de una edificación reforzada con muros de concreto armado y disipadores de fluido viscoso para evaluar su efectividad desde el punto de vista estructural. Por ello, se ha evaluado la estructura existente para verificar la necesidad de reforzar. Luego, se ha evaluado el edificio incorporando muros estructurales para determinar su comportamiento sísmico. También, se ha evaluado el edificio añadiendo disipadores, para ello se tuvo en cuenta la ubicación de los dispositivos con los valores del coeficiente de amortiguamiento, y de ese modo analizar el comportamiento sísmico. De acuerdo a la evaluación, se obtuvo una reducción máxima de distorsiones del 74% y 76% en X para el edificio con muros y disipadores respectivamente, y para Y el 65% en el edificio con muros y el 56% con disipadores en ambos casos comparados con la estructura actual. De los resultados, se puede apreciar que en ambos reforzamientos las distorsiones se reducen cumpliendo con lo permisible. Asimismo, en relación a las cortantes se obtuvo que en el edificio con muros incrementa en 143% al edificio existente, sin embargo, los desplazamientos se disminuyen; y en el reforzamiento con disipadores se reducen en 26% en comparación al edificio en estudio, ello es de gran relevancia debido a que los elementos estructurales van a soportar menor fuerza sísmica. Por lo tanto, la propuesta con disipadores es la más efectiva, debido a que posee menor intervención de área y reduce el movimiento sísmico en la estructura.This thesis is focused on the study of comparative seismic behavior of a building reinforced with concrete walls and fluid viscous dampers to evaluate its structural effectiveness. Therefore, the existing structure has been evaluated to verify the need for reinforcement. The building has then been evaluated incorporating structural walls to determine its seismic behavior. Also, the building has been evaluated by adding fluid viscous dampers, for this took into account the location of the devices with the values of the damping coefficient, and thus analyze the seismic behavior. According to the evaluation, a maximum reduction of distortions of 74% and 76% in X was obtained for the building with walls and dampers respectively, and for Y the 65% in the building with walls and the 56% with dampers in both cases compared to the current structure. From the results, it can be seen that in both reinforcements the distortions are reduced by complying with the permissible. Also, in relation to the forces, it was obtained that in the building with walls increases in 143% to the existing building, however, the displacements are decreased; and in the reinforcement with dissipaters are reduced by 26% compared to the building under study, this is of great relevance because the structural elements will withstand less seismic force. Therefore, the proposal with fluid viscous dampers is the most effective, because it has less area intervention and reduces the seismic movement in the structure.
Tesis
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Hoque, Md Zaydul Carleton University Dissertation Engineering Civil. "Seismic response of retaining walls." Ottawa, 1992.
Find full text
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Wong, Sze-man. "Seismic performance of reinforced concrete wall structures under high axial load with particular application to low-to moderate seismic regions." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B34739531.
Full text
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Wijanto, Ludovikus Sugeng. "Seismic Assessment of Unreinforced Masonry Walls." Thesis, University of Canterbury. Civil and Natural Resources Engineering, 2007. http://hdl.handle.net/10092/1680.
Full textAbstract:
This thesis focuses on the seismic performance of unreinforced masonry wall perforated with
a door opening representing typical URM walls of many aged masonry buildings in
Indonesia. To obtain a test result that will be able to represent the local conditions, the
experiments have been conducted in the Research Institute for Human Settlements (RIHS)
laboratory in Bandung-Indonesia.
Two 75 % unreinforced masonry (URM) walls with a 1½-wythe of solid clay-brick were
constructed in Dutch bond configuration and tested until failure under quasi-static-reversed
cyclic loading. Both units were loaded vertically by constant loads representing gravity loads
on the URM wall’s tributary area. Both models were constructed using local materials and
local labours. Two features were taken into account. First, it accommodated the influence of
flanged wall and second, the URM wall was built on the stone foundation. The first URM
wall represent the plain existing URM building in Indonesia and second strengthened by
Kevlar fibre.
It was observed from the test results that the URM wall Unit-1 did not behave as a brittle
structure. It could dissipate energy without loss of strength and had a post-elastic behaviour in
terms of “overall displacement ductility” value of around 8 to 10. As predicted, the masonry
material was variable and non homogeneous which caused the hysteresis loop to be non
symmetrical between push and pull lateral load directions. It can be summarized that Kevlar
fibre strengthening technique is promising and with great ease of installation. Although
Kevlar material is more expensive when compared to other fabrics as long as it was applied at
the essential locations and in limited volumes, it can significantly increase the in-plane URM
wall capacity. With appropriate arrangements of Kevlar fibre, a practicing engineer will be
able to obtain a desired rocking mechanism in the masonry structure. Another advantage for
the architectural point of view, very thin Kevlar fibres do not reduce the architectural space.
Studies have also been undertaken to analyze the in-plane response of plain URM wall before
and after retrofiting using the current seismic standard and the Finite Element Method (FEM).
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Fairless, G. J. "Seismic performance of reinforced earth walls." Thesis, University of Canterbury. Engineering, 1989. http://hdl.handle.net/10092/7562.
Full textAbstract:
Previous seismic testing of reinforced earth walls, and present design methods, are outlined.
Six one metre tall model reinforced earth walls were tested under normal gravity on a shaking table. Accelerations, displacements and reinforcing strip forces were measured. A series of simple sinusoidal single-pulse wave forms, and the El Centro 1940 north-south recorded earthquake motion were used as input to the shaking table.
Permanent outward displacement of a block consisting of the facing, part of the reinforced block, and a wedge of retained soil behind the reinforced block occurred when a limiting or yield acceleration was exceeded. The wall facing remained essentially vertical. The critical (minimum) yield acceleration was found to occur when and after the failure surface outcropped at the fill surface. This critical yield acceleration was calculable using a limiting equilibrium formulation, within the variability of the observed results. A sensitivity analysis of the formulation is presented.
The apparent soil friction angle is found to reduce during repeated seismic shaking, while the apparent soil-strip friction coefficient is found to increase probably to a limiting value. In design, the peak value of the friction coefficient found from direct shear tests between the soil and reinforcing can be used. To calculate design strip forces, an upper bound seismic earth pressure coefficient based on the Mononobe-Okabe dynamic earth pressure coefficient KAE is proposed.
Measured displacements are plotted on charts for three sliding block displacement prediction methods. One approach, using random vibration and probability theory, is more rational and complete than the others, and provides an estimate of the prohability of exceedence of the calculated displacement. The method is quite complicated, however, and for everyday design a simple upper bound on a chart derived from an equivalent pulse technique is recommended.
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Paterson, James 1974. "Seismic retrofit of reinforced concrete shear walls." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33986.
Full textAbstract:
A series of four shear wall specimens was tested in order to evaluate a seismic retrofit that has been proposed for the core wall of an existing building in Berkeley, California. Like many reinforced concrete shear walls that were built in the 1960s and early 1970s, the core wall in this building was constructed with reinforcement details that would result in a non-ductile seismic response. These poor details include lap splices in the longitudinal reinforcement in regions where flexural yielding is expected, inadequate confinement of the boundary regions, and inadequate anchorage of the transverse reinforcement. The proposed seismic retrofit involved the use of headed reinforcement, carbon fibre wrap, and reinforced concrete collars at the base of the wall.The four shear wall specimens were tested under reversed cyclic loading. Two of these walls had a lap splice in the longitudinal steel at the base of the wall and the other two had a lap splice 600 mm from the base of the wall. One of each of these specimens was tested in the 'as-built' condition and the other two were retrofit prior to testing. The test results show that the retrofit strategies were successful in improving the ductility and energy dissipation of the shear walls.
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Zervos, Spyridon M. Eng Massachusetts Institute of Technology. "Seismic performance of single-propped retaining walls." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104250.
Full textAbstract:
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 51-52).
This thesis analyzed the dynamic performance of single-propped retaining walls in dry sand under different seismic excitations using the finite difference software FLAC v7.0 (Itasca). The structure comprises two reinforced concrete diaphragm walls connected by a row of cross-lot struts that is used to support a 9.5m deep, 18m wide excavation in dry sand. After simulating the excavation as a staged construction, a suite of thirty-two (32) different seismic inputs were applied at the base of the model. The non-linear, inelastic soil behavior was represented by the advanced PB constitutive model (generalized effective stress soil model) developed by Papadimitriou et al. (2002). In order to avoid spurious reflections of shear waves on the vertical boundaries of the finite difference model, the analyses used periodic boundary conditions. The performance of the structure was investigated by considering the wall deflections, bending moments, earth pressures and surface settlements for each of the applied ground motions. Based on the horizontal deflection of the walls, three distinct categories of performance were observed and characterized. Results of the parametric study were correlated with the characteristics of the ground motions from which wall deflections and bending moments showed clear correlations with peak ground acceleration and Arias intensity.
by Spyridon Zervos.
M. Eng.
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Upreti, Manohar Raj. "BEHAVIOR OF FOUNDATION BEAM FOR SHEAR WALL STRUCTURAL SYSTEM WITH COUPLING BEAMS." OpenSIUC, 2019. https://opensiuc.lib.siu.edu/theses/2635.
Full textAbstract:
The purpose of this study is to analyze the foundation beam linked between two shear walls in the presence of lateral loads. Mat foundation with shear walls is one of the most commonly used reinforced concrete structural systems to resist the lateral load. When two independent walls are connected with a link beam, also known as the coupling beam, the overturning resistance of the building is largely increased. However, the coupling beams are relatively weaker structures and can develop larger stresses. When there is a mat foundation, or pile cap in case of pile foundation, the part of the foundation which is right below the coupling beam where no shear wall is present, will also get large stresses due to the highly rigid nature of adjacent shear walls. Most of the lateral deformations are imposed only on the coupling beams and foundation beam. There is not much literature or design procedure found in books and codes to mitigate the high risks associated with the foundation beam between shear walls on its design vulnerability. This thesis is focused on the risks associated with exceptionally high forces on the foundation beam due to earthquake forces.
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Yathon, Jeffrey Scott. "Seismic shear demand in reinforced concete cantilever walls." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/33649.
Full textAbstract:
This thesis addresses the issue of seismic shear force demand in reinforced concrete cantilever walls, and specifically the dynamic amplification of shear force due to higher mode effects. Current design codes either do not account for this phenomenon, or vary considerably in the approach they take. In order to determine the reason for the variation, previous research is first examined, and it is found that the conclusions reached are not consistent with each other. It is identified that a major source of the problem is a lack of a comprehensive analysis of the problem.
To attempt to address this issue, the analysis portion of the thesis starts by performing response spectrum analysis on structures with heights ranging from 5 to 70 storeys. It is shown that when a pin is placed at the bottom of the structure to simulate yielding, the moment is limited but the shear can still increase. A simple relationship between the fixed base and pinned base shear is found. Reduction in the shear stiffness, possible yielding higher in the structure, and the effect of the spectrum are also issues examined.
The next two chapters deal with both linear and nonlinear time history analyses performed using OpenSees. Linear time history analysis is used to demonstrate the issues with ground motion scaling in tall structures. It is then shown that the shear at the base of the structure from a nonlinear analysis is more than the code predicts, as is the moment higher up in the structure. Furthermore, the shear at the base of the structure remains relatively constant no matter how the rest of the structure yields. A possible model is then proposed which adds the pinned response spectrum analysis results to the reduced shear. This model is compared to the nonlinear results and it is found to agree well.
Finally, a chapter is devoted to factors which may complicate the results. They are separated into two sections: choice of hysteretic model, and the influence of the shear capacity on the demand. It is determined that further research is needed in these areas.
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Rajaee, Rad Babak. "Seismic shear demand in high-rise concrete walls." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/6484.
Full textAbstract:
Concrete shear walls are used as the seismic force resisting system in many high-rise buildings in Western Canada. During earthquake, the response of a high-rise concrete wall as it undergoes severe cracking of concrete and yielding of reinforcement is very complex. In particular, the nonlinear shear behaviour of concrete shear walls is not well known; therefore available analysis programs generally use very primitive models for nonlinear shear behaviour. Gérin and Adebar (2004) quantified the observed experimental results on reinforced concrete membrane elements and presented a simple nonlinear shear model that included the influence of concrete diagonal cracking, yielding of horizontal reinforcement and ultimate shear capacity.
There are a number of important issues in the design of high-rise concrete shear walls where shear deformations play a very important role and hence nonlinear shear behaviour will have a significant influence. In this dissertation, three different seismic design issues where nonlinear shear response plays a significant role are investigated.
The first issue which is of considerable concern to designers is the large reverse shear force in high-rise concrete walls due to rigid diaphragms below the flexural plastic hinge. The nonlinear analyses that were carried out in this study show that diagonal cracking and yielding of horizontal reinforcement significantly reduce the magnitude of reverse shear force compared to what is predicted by using linear analysis procedures.
A second issue where nonlinear shear behaviour has a significant influence is associated with the shear force distribution between inter-connected high-rise walls of different lengths. The results presented in this work, show that when diagonal cracking is included in the analysis, significant redistribution of shear forces takes place between walls and all walls do not necessarily yield at the same displacement.
The third issue is related to the dynamic shear demand caused by influence of higher modes and the corresponding nonlinear action that takes place in tall cantilever walls. According to the nonlinear dynamic analyses that were performed, the influence of hysteretic shear response on the seismic demand of high-rise concrete walls was investigated.
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Harries, Kent A. (Kent Alexander). "Seismic response of steel beams coupling concrete walls." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=56617.
Full textAbstract:
Ductile coupled flexural walls are critical lateral load resisting systems of many structures. The coupling beams of these structures must exhibit excellent ductility and energy absorption ability. To achieve better ductility and energy absorption than previously possible, the use of steel link beams with their ends embedded in the reinforced concrete walls is proposed. Preliminary experimental results are reported for two full-scale reversed cyclic loading tests of portions of ductile flexural walls coupled with steel link beams. The excellent performance, together with the ease of construction, demonstrate the feasibility of this alternative form of construction. In order to ensure ductile response, design and detailing guidelines for both the clear span and embedded portions of the link beams and the reinforced concrete embedment region are presented. An assessment, based on comparisons with other structural systems, of this novel type of construction is presented.
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Stewart, Wayne. "The seismic design of plywood sheathed shear walls." Thesis, University of Canterbury. Department of Civil Engineering, 1987. http://hdl.handle.net/10092/2458.
Full textAbstract:
A design methodology for earthquake resistant plywood sheathed shear walls
is presented. The sheathing nailing is selected as the ductile load
limiting element, whereby the large displacement demands imposed during an
earthquake can be sustained without failure of the timber members in
bending, shear or tension. Analytical models for predicting the elastic
behaviour and ultimate strength of shear walls are formulated in order to
develop the design procedure.
An experimental study of nailed sheathed joints was undertaken, and showed
that such joints were able to sustain large reverse cycles well into the
inelastic range. Complementary to the experimental study, an analytical
strength model for nailed joints is described, and identifies nail
diameter, nail length and nail coating as being the variables most
influential on joint strength.
Eleven full scale plywood sheathed shear walls were subjected to reverse
cyclic quasi-static loading and shaketable excitation. The performance of
the sheathing nailing, framing connections and anchorage connections is
reported in detail. The test walls exhibited progressive stiffness
degradation resulting in pinched hysteresis loops, prior to failure through
the nail heads pulling through the plywood, or the nail point withdrawing
from the framing.
A theoretical time-history single degree of freedom idealisation is
described to predict the dynamic response of shear walls. Theoretical
predictions compared well with the experimental shaketable behaviour of the
full scale test walls.
The displacement demands on shear walls which exhibited pinched hysteresis
loops are compared with the corresponding displacement demands on an
elastoplastic structure.
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Layssi, Hamed. "Seismic retrofit of deficient reinforced concrete shear walls." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119578.
Full textAbstract:
This research describes an experimental and analytical investigation to evaluate the seismic performance of poorly designed and detailed reinforced concrete (RC) flexural shear walls both in their as-built conditions and after being retrofitted. Older shear walls have several deficiencies which make them vulnerable in case of moderate to severe earthquakes. Full-scale shear wall specimens were constructed and tested under reversed cyclic loading. Two different techniques were chosen to retrofit the deficient walls in order to improve the overall performance. A retrofit technique using Carbon Fibre Reinforced Polymer (CFRP), having minimum intervention, was studied to determine the seismic performance. A more labour-intensive repair technique, including the addition of a reinforced concrete jacket in the critical region (location of potential plastic hinging and lap splices of vertical bars) together with CFRP wrapping was also studied. The responses obtained from experiments were used to develop behavioural models, capable of representing the global responses of the walls, as well as critical failure modes observed in the experiments. These models provide useful tools for predicting the complete reversed cyclic loading responses of shear walls. The analytical models were used to predict the responses of a deficient prototype wall-frame structure in its original condition as well as after retrofit, subjected to different seismic hazard levels. This study enabled an evaluation of the performance of the prototype structure to determine the effectiveness of retrofit and repair measures.Cette recherche présente une étude expérimentale et analytique pour évaluer la performance sismique des murs des contreventements déficients avant et après réhabilitation sismique. Les murs représentent la construction typicalité des 1960's et ils sont plusieurs déficiences. Les murs à grande échelle ont été construits et soumises à des charges cycliques alternées. Deux techniques différentes ont été choisies et examiné pour la réhabilitation sismique des murs déficients. Une méthode de dimensionnement de réhabilitation sismique, avec l'intervention minimale, utilisant de polymères renforcés de fibres de carbone (PRFC). La deuxième technique compris l'ajout d'une chemises en béton armé (renforcés de fibres d'acier et des armatures) dans la région critique (la région de rotule plastique potentielle et du chevauchement des armatures verticales), accompagnée PRFC pour l'amélioration résistance cisaillement de murs. Les réponses obtenues à partir d'expériences fournissent des informations importantes sur les caractéristiques des murs des contreventements qui peuvent être utilisées pour développer modèles comportementaux et calibrer des techniques de prédictions numériques. Ces modèles sont capables de représenter les réponses globales des murs. Les modèles numérique ont été utilisés pour prédire les réponses d'un vieux bâtiment (ossatures résistantes au moment munies de murs de contreventement) de cinq étages en béton armé dimensionne selon le code 1963 de l'ACI ((American Concrete Institute) et Code national du bâtiment 1965 du Canada (CNBC), et pourrait être vulnérables lors de séismes forts ou même modères. Le bâtiment est analyse (statique pushover et l'analyse dynamique de l'historique temporel) dans le régime non-linéaire avant et après réhabilitation séismique des murs.
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Amirzehni, Elnaz. "Seismic assessment of basement walls in British Columbia." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57846.
Full textAbstract:
The current state of practice for seismic design of basement walls in Vancouver is based on the Mononobe-Okabe (M-O) method using a Peak Ground Acceleration (PGA) mandated by the National Building Code of Canada (NBCC, 2010). Because there is a little evidence of any significant damage to basement walls during major earthquakes, the Structural Engineers Association of British Columbia (SEABC) became concerned about designing the walls under the code-mandated PGA and set up a task force to review the current procedure for seismic design of basement walls in British Columbia (BC). The University of British Columbia (UBC) was asked to carry out this investigation. This thesis aims to provide solid base for designing the basement walls using an appropriate fraction of the code-mandated PGA in the M-O analyses. To this end, a series of dynamic nonlinear soil--structure interaction analyses are conducted to examine the seismic resistance of typical basement walls designed according to current practice in BC, for different fractions of the code mandated PGA (100% to 50%). The seismic responses of the walls are evaluated by subjecting them to ensembles of ground motions comprised of shallow crustal, deep subcrustal, interface earthquakes from a Cascadia subduction events and near-fault earthquake motions. Input motions are matched to the intensity of the seismic hazard using both spectral and linear scaling techniques. Representative 4-level and 6-level basement walls are analyzed. The nonlinear hysteretic response of the foundation soil is characterized in order to obtain realistic estimates of an interaction between the basement wall and the surrounding soil. In addition, the effects of the local site conditions in terms of geometrical and geological structure of soil deposits underlying the basement structure on the seismic performance of the basement walls are evaluated. The analyses show that current engineering practice for designing basement walls based on the M-O method and using 100% PGA is too conservative. The analyses suggest that a wall designed using 50% to 60% PGA results in an acceptable performance in terms of drift ratio.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Karakus, Hulya. "New Seismic Design Approaches For Block Type Quay Walls." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608584/index.pdf.
Full textAbstract:
In this study, new design approaches are introduced for the seismic design of block type quay walls after reviewing the conventional methodologies. Within the development of the new design approaches an inverse triangular dynamic
pressures distributions are applied to define both seismic earth pressures and seismic surcharge pressures. Differently from the conventional design methodology, the hydrodynamic forces are taken into consideration while dynamic forces are specified and equivalent unit weight concept is used during
the both static and dynamic calculations Compatibility of this new design approaches are tested by case studies for the site and it is seen that the numerical results are in good agreement qualitatively with field measurements.
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Boudreault, Félix-Antoine. "Seismic analysis of steel frame wood panel shear walls." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=83851.
Full textAbstract:
The use of steel frame/wood panel shear walls as a seismic force resisting system (SFRS) in residential and/or commercial buildings is expected to increase in the future. At the moment, in Canada, however, no specific guidelines in line with the seismic provisions of the National Building Code of Canada (NBCC) exist with which the engineer can design a building consisting of these shear walls. An extensive research program has therefore been undertaken at McGill University to develop a design method through the testing of different configurations of steel frame/wood panel shear walls loaded with monotonic and reversed cyclic protocols. A total of 16 wall configurations (109 walls) were tested over the course of the study. The CUREE Ordinary Ground Motions loading protocol was selected to represent the reversed cyclic regime because it was found to best correspond to the demand that would be imposed on a steel frame I wood panel shear wall during a typical seismic event.The analysis of test results in order to extract the principal design information was carried out using an Equivalent Energy Elastic-Plastic (EEEP) model. A ductility related (Rd) and an overstrength related (Ro) force modification factor are required for the calculation of equivalent static seismic loads following the 2005 NBCC design provisions. Values of Ro = 1.8 and Rd = 2.5 have been determined and are recommended on a preliminary basis.
The Stewart hysteretic model was found to best represent the strength and stiffness characteristics of a steel frame/wood panel shear wall component. The subsequent evaluation of building models that incorporate the Stewart model using non-linear time history dynamic analyses could then be carried out to validate the assumptions made by the EEEP method on the system ductility and the corresponding force modification factors.
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Hsiaw, Jennifer S. (Jennifer Sing-Yee). "Seismic load-resisting capacity of plastered straw bale walls." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/60773.
Full textAbstract:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 57-58).
Straw bales have been incorporated into buildings for centuries, but only recently have they been explored in academic settings for their structural potential. Straw bale building is encountering a growing audience due to its social and economic benefits. Plastered and reinforced straw bale wall assemblies have been found comparable to wood frame construction in resisting vertical and lateral loads. A number of straw bale residences have been constructed in the highly seismic state of California, while recent efforts have expanded its presence to quake-prone areas in developing countries like Pakistan and China. As this is a burgeoning arena of research, only empirical tests have been conducted. This thesis introduces a computer simulation of a wall assembly under lateral loading, using two techniques: a multi-layer shell element and an equivalent compression strut frame in SAP2000. The models assume homogeneity, and based on the results, areas for improvement and further research are suggested.
by Jennifer S. Hsiaw.
M.Eng.
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Powrie, W. "The behaviour of diaphragm walls in clay." Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372634.
Full text
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Erdogdu, Murat. "In Plane Seismic Strengthening Of Brick Masonry Walls Using Rebars." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12610114/index.pdf.
Full textAbstract:
About half of the total building stock in Turkey is masonry type building.
Masonry buildings in Turkey, especially in rural areas, are constructed without any
engineering knowledge mostly by their own residents. They generally have heavy
roofs. Masonry type buildings also have thick and heavy wall materials. Heavy
roof and wall material generate large inertial forces in the case of an earthquake.
Brittle failure of walls leads to total failure of whole system followed by sudden
collapse of heavy roof. The aim of this thesis is to understand failure mechanisms
of brick masonry walls, prevent their brittle failure and allow the walls to dissipate
energy during an earthquake. Furthermore, ultimate capacity increase was also
targeted by using low cost and easy to obtain material.
In order to find an economical and effective way in strengthening of brick masonry
walls in their in-plane direction, steel rebars were used as post-tensioning materials
in brick masonry walls and house tests. Springy connections were utilized in the
reinforcing and post-tensioning bars in order to prevent early loss of post-tension
due to wall cracking or rebar yielding. Separate tests were conducted with and
without rebars and springs in order to compare their results.
v
The test results indicated that the ultimate lateral load capacity of 6m long brick
masonry house increased up to about 6 times with respect to its nominal value.
Energy dissipation also increased up to about 10 times of the original house.
Lateral load capacity increase in 2m long rebar post-tensioned brick masonry walls
were measured as about 17 times when compared with the original wall. The
energy dissipation capacity was also increased about 30 times the nominal value.
A general procedure was developed to assess the vulnerability of single storey
masonry houses, which calculates the earthquake demand acting on each wall
segment. Comparison of capacity versus demand enables evaluation of wall
segments and leads strengthening calculations if necessary. Derived formulas were
used to calculate post-tensioning force and design vertical and diagonal rebars. The
procedure was demonstrated using properties of an existing house and
strengthening cost was found to be about 10% of the building cost.
The results of the conducted tests have shown that rebar post-tensioning of brick
masonry walls is an effective and cost-efficient way of strengthening the walls in
their in-plane direction and can be used as an economical and simple technique for
seismically vulnerable masonry houses. Spring based connection detail has
improved the post cracking performance of the walls at large deformations by
keeping the wall reaction higher after ultimate strength has reached as well as
increased the energy dissipation capacity of the walls.
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Balh, Nisreen. "Development of seismic design provisions for steel sheathed shear walls." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86724.
Full textAbstract:
Seismic design provisions for cold-formed steel sheathed (CFS) shear walls are not available in the NBCC or in the CSA-S136 Standard. This limits engineers in designing with such walls in seismic zones across Canada. The objective of this research was to develop design provisions for steel sheathed shear walls constructed with CFS framing.To develop such standards, 54 walls of various configurations were tested at McGill University in the summer of 2008. The walls varied in framing and sheathing thickness, detailing and aspect ratio. The tests carried out at McGill were used to obtain design values for Canada and to confirm the US values that are listed in the AISI S213 Lateral Design Standard.
There were two types of tests carried out; monotonic and reversed cyclic. The monotonic tests consisted of a static load simulation to eliminate any strain rate effects and the wall specimen was pushed laterally to its limits. The second type of test followed the CUREE reversed cyclic protocol where the wall was loaded laterally in both directions following a series of increasing displacement amplitudes up to failure.
Test results were incorporated with data obtained from the US to determine nominal shear resistance values, corresponding resistance factor, overstrength and ductility factors as well as seismic force modification factors. The test data was analyzed using the Equivalent Energy Elastic-Plastic (EEEP) approach which provides an equivalent bi-linear elastic plastic curve to the non linear behaviour exhibited by shear wall tests by considering the total energy dissipation. Based on the test results, a material resistance factor, phi, of 0.7, an overstrength value of 1.4, a ductility-related force modification factor, Rd, of 2.5 and an overstrength-related force modification factor, Ro, of 1.7 are recommended.
Dynamic analysis of multi-storey structures was carried out to validate the recommended R-values and to determine height limits. According to FEMA P695, which provides a methodology for determining the lateral performance of lateral framing systems, the test based seismic force modification factors were shown not to provide an acceptable level of safety against collapse. Subsequent analyses resulted in a recommendation of an Rd value of 2.0 and an Ro value of 1.3. A maximum height limit of 15m is also proposed.
Les dispositions séismiques pour la conception de murs de refends en acier laminé à froid ne sont pas disponibles dans le Code National du Bâtiment de Canada (CNBC) et la norme CSA S136 de l'Association Canadienne de Normalisation. Cela limite la capacité des ingénieurs à concevoir de tels murs dans les zones à activité sismiques à travers le Canada. Le but de cette recherche était de développer ces dispositions de conception sismique pour les murs de contreventements en acier laminé à froid.
Pour développer de tels directives, 54 murs de configurations diverses furent testés à l'université McGill au cours de l'été 2008. Ces configurations variaient l'epaisseur des colombages et l'épaisseur des panneaux d'acier ainsi que les arrangements et espacements des connexions et la longueur de murs. Les tests menés à McGill furent utilisés pour obtenir les valeurs nécessaires à la conception au Canada et à confirmer les valeurs des États-Unis listées dans le AISI S213 Lateral Design Standard.
Deux types de tests furent menés, soit à chargement monotone et cyclique-réversible. Les tests à chargement monotone consistaient en une simulation à chargement statique afin d'éliminer tout effet de déformation et les murs furent poussés latéralement jusqu'à leurs limites. Le second type de test suivit le protocole de chargement cyclique-réversible de CUREE où les murs furent chargés latéralement vers les deux directions suivant une série de déplacements à amplitudes croissantes menées jusqu'à l'effondrement.
Les résultats des tests furent incorporés avec les données obtenues des États-Unis pour déterminer les valeurs nominales de résistance en cisaillement, les facteurs de résistance correspondants, la sur-résistance et les facteurs de ductilité ainsi que les facteurs de modification de force séismiques. Les données des tests furent analysées en utilisant la méthode équivalente de l'énergie élasto-plastique (EEEP) qui fournit une courbe équivalente bilinéaire d'élasticité plastique au comportement non-linéaire démontré par les tests des murs de contreventements en acier laminé à froid en tenant compte le la dissipation totale d'énergie. En se basant sur les résultats de ces tests, un facteur de résistance de matériel, phi, de 0.7, une valeur de sur-résistance de 1.4, un facteur de modification de force relié à la ductilité, Rd, de 2.5 et un facteur de modification de force relié à la sur-résistance, Ro, de 1.7 sont recommandés.
Une analyse dynamique sur des structures à multiples étages fut menée pour valider les facteurs de modification de la charge sismique recommandés et pour déterminer les limites d'hauteur. Selon le FEMA P695, qui fournit une méthodologie pour déterminer les performances latérales des systèmes à charpente latéral, les facteurs de modification de force sismique basé sur des tests n'ont pas prouvé fournir un niveau acceptable de sécurité contre l'effondrement.
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Harries, Kent A. (Kent Alexander). "Seismic design and retrofit of coupled walls using structural steel." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29040.
Full textAbstract:
The reversed cyclic loading responses of reinforced concrete walls coupled with steel beams are investigated. Four full-scale segments of coupled walls having both "shear critical" and "flexure critical" steel coupling beams with their ends embedded in the walls were tested. The reversed cyclic loading responses of these specimens are compared with those of conventionally reinforced and diagonally reinforced concrete coupling beams. Design and detailing guidelines are proposed for both the steel coupling beams and the reinforced concrete embedment regions. Non-linear dynamic analyses of prototype coupled wall structures, comparing conventional and diagonal reinforcement details with the proposed flexure and shear critical steel coupling beams are presented.Four full-scale reversed cyclic loading tests of shear deficient reinforced concrete coupling beams were conducted to study efficient ways of retrofitting these beams. An unretrofitted control specimen and three specimens with different retrofit details were tested. The retrofit procedure investigated involved applying steel plates to one side of the coupling beams to determine ways of increasing the shear strength of the beams such that the nominal flexural capacity may be attained. Different methods of attaching the retrofit plates using structural epoxy and mechanical anchor bolts are investigated. A method for determining the influence of the steel plate retrofit on the shear capacity of the beam is developed. Non-linear dynamic analyses comparing the structural responses of unretrofitted and retrofitted prototype structures are also presented.
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Tupper, Bryce. "Seismic response of reinforced concrete walls with steel boundary elements." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0023/MQ50667.pdf.
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Martins, Andreia Piedade Gomes. "Seismic behaviour of masonry veneer walls." Doctoral thesis, 2018. http://hdl.handle.net/1822/59015.
Full textAbstract:
Tese de Doutoramento em Civil EngineeringIt is recognized that masonry veneer walls, commonly used in commercial, industrial and residential buildings can be vulnerable to earthquakes and most of the reported cases of failures are due to poor materials, design and inadequate construction practices. This inadequate behaviour has promoted research on the seismic behaviour of brick veneer walls mostly attached to structural systems composed of light timber and steel frames but this work aims to contribute to the knowledge of seismic behaviour of masonry veneer whose backing support is composed by brick masonry infill walls enclosed in RC frames that is a construction system common in Portugal and South of European countries. In detail, this thesis aims at: (1) analyse at the local level the mechanical behaviour of connections of wall ties between the brick veneer walls and masonry infill walls; (2) assess the mechanical behaviour of brick veneer walls under out-of-plane loads for different configurations of ties; (3) carry out an overview of standards and provide design and construction guidelines under seismic action for brick masonry veneer walls. To accomplish this, an extensive experimental program was designed, being divided mainly in two phases: (1) mechanical and physical characterization of materials components, such mortar, bricks and brick masonry. An extensive experimental campaign on cyclic tension-compression and shear tests on different tie-masonry assemblages was performed. Different parameters were considered, namely the type of tie, width of the air cavity, mortar strength and embedment length of the ties; (2) cyclic out-of-plane tests on brick masonry veneer walls attached to brick masonry walls enclosed in a RC frame. In this experimental campaign it was also varied the type of ties, air cavity width, embedment length and the effect of previous in-plane loading. The experimental work is complemented with analytical tools to define hysteric laws to represent the cyclic tension-compression and shear behaviour of ties, which can be used in further numerical studies. It was concluded that the tension-compression behaviour of connections is influenced by the type of wall tie and air cavity width. The stiffness of tie and free length influences significantly the compression behaviour and the shape of tie and embedment length of the tie control the tensile behaviour. The out-of-plane behaviour of the brick veneer walls depend also on the type and number of ties, and on the air cavity width. Both parameters control the out-of-plane performance from the brick veneer walls to the backing wall.
As paredes de alvenaria de fachada, habitualmente aplicadas em edifícios comerciais, industriais e residenciais, podem ser vulneráveis a terremotos e a maioria dos casos de rotura registados deve-se a materiais pobres, projeto e práticas inadequadas de construção. Esse comportamento inadequado tem promovido investigação sobre o comportamento sísmico de paredes de alvenaria de fachada principalmente conectadas a sistemas estruturais constituídos por madeira e estruturas metálicas. Este trabalho visa compreender o comportamento sísmico de paredes de fachada, cujo suporte é composto por paredes de enchimento inseridas em pórticos de betão armado, sendo um sistema de construção comum em Portugal e no sul da Europa. Em detalhe, esta tese pretende: (1) analisar localmente o comportamento mecânico das conexões com ligadores entre a parede de fachada e a parede de enchimento; (2) avaliar o comportamento mecânico de paredes de alvenaria de fachada sob carregamento fora do plano em diferentes configurações de conexões; (3) desenvolver uma revisão de normas e fornecer diretrizes de projeto e construção para paredes de alvenaria de fachada. Com efeito, foi desenvolvido um extenso programa experimental, sendo dividido principalmente em duas fases: (1) caracterização mecânica e física dos componentes do sistema, tais como argamassas, tijolos e alvenaria. Foi realizada uma extensa campanha experimental de ensaios cíclicos de tração-compressão e corte em diferentes tipos de conexões. Consideraram-se diferentes parâmetros, nomeadamente o tipo de ligador, a largura da cavidade de ar, a resistência da argamassa e o comprimento de embebimento dos ligadores; e (2) ensaios cíclicos fora de plano em paredes de alvenaria de fachada ligadas a paredes de enchimento inseridas em pórticos de betão armado. Nesta campanha experimental também foi avaliado o tipo de ligador, a largura da cavidade de ar, o comprimento de embebimento e efeito de dano prévio no plano. O trabalho experimental foi complementado com ferramentas analíticas para definição de leis histeréticas para a representação do comportamento de compressão-tração e corte das conexões, que podem ser usadas em estudos numéricos adicionais. Concluiu-se que o comportamento de compressão-tração das conexões é influenciado pelo tipo de ligador da parede e pela largura da cavidade de ar. A rigidez do ligador e o comprimento livre influenciam significativamente o comportamento à compressão. O tipo de ligador e o comprimento de embebimento do ligador controlam o comportamento à tração. O comportamento fora do plano das paredes de alvenaria depende também do tipo e número de ligadores e da largura da cavidade de ar. Ambos os parâmetros controlam o desempenho fora do plano das paredes de alvenaria de fachada e da parede de suporte.
Fundação para a Ciência e Tecnologia (FCT) - Pelo financiamento através da Bolsa de Doutoramento SFRH/BD/96484/2013. Este trabalho foi parcialmente financiado pelos fundos FEDER através do Programa Operacional Fatores de Competitividade - COMPETE e pelos fundos nacionais da FCT no âmbito do projeto POCI-01-0145-FEDER-0076 33
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Leite, João C. "Seismic behaviour of masonry infill walls : test and design." Doctoral thesis, 2014. http://hdl.handle.net/1822/35074.
Full textAbstract:
Tese doutoramento em "Civil Engineering"Several factors influence the behaviour of infilled frames, which has been studied in the last fifty years. One might assume that so many years of research in one theme might be enough to nearly fully understand it but this is not the case. The new generation of design standards, namely the Eurocode 8 (EC8), impose the use of reinforcement in these walls in order to prevent a brittle collapse and makes the structural engineer accountable for this requirement, yet it fails to provide enough information for the design. Motivated by the stated reasons, this thesis aims at understanding the seismic behaviour of infill walls when designed following the prescriptions of the EC8, therefore reinforced with bed joint and plaster reinforcement, and compares them to the seismic behaviour of the infill walls considered as a standard in the last three decades in Portugal, which is an unreinforced double leaf. For this purpose, three RC concrete buildings were constructed at a scale of 1:1.5 and tested on the shaking table of the National Laboratory for Civil Engineering, Portugal, each with a different infill solution but with the same geometry. Next, the experimental results were compared, in terms of demand and capacity, with the analytical solutions proposed by different authors and design standards. A numerical study was carried out, which includes model updating and non-linear static analysis. Finally, two novel design proposals are presented: one regarding the analytical computation of the natural frequency of infill walls; another regarding the reduction of the out-of-plane capacity of the infill wall due to the presence of openings. The experimental tests show that the double leaf unreinforced infill walls underperformed during a large earthquake, collapsing out-of-plane by rotating as a rigid body around the base line of the model. The infill walls with bed joint and plaster reinforcement did not collapse out-of-plane due their connection to the RC frame. The comparison done between the experimental results and analytical solutions of the design standards show that the formulation proposed by the EC8 presents acceptable results for most of the infill walls in the present work, as far as the out-of-plane demand is concerned. As for the capacity, the EC6 and FEMA 306 provide acceptable results. Both design proposals present a good correlation with the experimental results.
São vários os factores que influenciam o comportamento de pórticos preenchidos por paredes de alvenaria e o seu estudo iniciou-se há cerca de cinquenta anos. Poder-se-ia assumir que tantos anos de investigação num tema seriam suficientes para o considerar como fechado, no entanto não é esta a situação. A nova geração de regulamentos, nomeadamente o Eurocódigo 8 (EC8), impõe novas regras para estes elementos como o uso de armaduras, proibição de roturas frágeis e responsabilização do projectista pelo comportamento sísmico, no entanto o regulamento não detalha um método de dimensionamento. Tendo isto em mente, a presente tese tem por objectivo a compreensão do comportamento sísmico das paredes de enchimento quando dimensionadas com recurso ao EC8, nomeadamente, reforçadas com armadura de junta ou reboco armado, comparando-o com o comportamento sísmico das paredes de enchimento construídas em Portugal nas últimas três décadas, ou seja, as paredes duplas sem armadura. Com este propósito, construíram-se três edifícios porticados de betão armado à escala de 1:1.5 e ensaiaram-se na mesa sísmica do Laboratório Nacional de Engenharia Civil. Cada edifício foi preenchido com uma solução diferente de paredes de enchimento mas todos partilhavam a mesma geometria. Os resultados experimentais são comparados com os resultados provenientes das soluções analíticas regulamentares, em termos de solicitação e resistência para fora-do-plano. Foi também efectuado um estudo numérico, incluindo a aplicação de técnicas de model updating e análises estáticas não lineares. Finalmente são propostas duas soluções analíticas novas com vista ao dimensionamento das paredes de enchimento: uma para calcular a frequência natural de vibração; outra para reduzir a resistência das paredes para fora-do-plano devido à presença de aberturas. Os resultados experimentais demonstraram que as paredes duplas sem armadura tiveram um comportamento não desejável no caso de um sismo extremo, pois colapsaram para fora-do-plano rodando como um corpo rígido em torno de um eixo na base do modelo. As paredes de enchimento com armadura de junta e reboco armado não colapsaram para fora-do-plano devido à sua conexão ao pórtico. A comparação dos resultados experimentais com os resultados analíticos dos regulamentos demonstrou que a formulação do EC8 apresenta resultados aceitáveis para a maioria dos enchimentos presentes no ensaio, no que respeita à determinação da acção para fora-do-plano. Relativamente à determinação da resistência para fora-do-plano, o EC6 e a FEMA 306 apresentam resultados aceitáveis. Ambas as propostas de dimensionamento apresentam também uma boa correlação com os resultados experimentais.
Fundação para a Ciência e a Tecnologia (FCT) grant SFRH/BD/62301/2009
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Poletti, Elisa. "Characterization of the seismic behaviour of traditional timber frame walls." Doctoral thesis, 2013. http://hdl.handle.net/1822/28845.
Full textAbstract:
Tese de doutoramento
Engenharia Civil - EstruturasTimber frame structures constitute an important cultural heritage of many countries, since they represent a typical anti-seismic construction adopted worldwide. Therefore, the preservation of these structures is of the utmost importance. Although recent earthquakes have pointed out the good seismic behaviour of this kind of structures, few experimental studies are available on the performance of traditional half-timbered walls and their retrofitting solutions. Aiming at filling this research gap and at better understanding the behaviour of these historic elements under seismic loads, an extensive experimental campaign has been carried out, performing in-plane cyclic tests on real scale half-timbered and timber frame walls, adopting connections and dimensions found in real structures and considering different infill types (brick masonry and lath and plaster). Moreover, considering possible damages caused by earthquakes, after the unreinforced tests, the walls were retrofitted and re-tested to compare the efficiency of the retrofitting solutions in terms of maximum load, ductility, cyclic stiffness, energy dissipation and equivalent viscous damping. Both traditional and innovative retrofitting techniques were adopted, namely bolts, steel plates and near surface mounted steel flat bars. Moreover, since the behaviour of the walls was governed by their connections, in-plane cyclic and pull-out tests were performed on traditional connections used in the walls. Additional retrofitting techniques were adopted, such as self-tapping screws and glass fibre sheets, to overcome some limitations found during the in-plane tests on the walls. From the experimental results, an analytical hysteretic model was derived, based on the modification of existing models and calibrated on experimental results. This can be used in simplified numerical models to represent the hysteretic response of the walls. Finally, numerical analyses were performed on timber frame walls with and without infill. The models were calibrated on the experimental results. Parametric analyses were then performed taking into account different variables.
Os edifícios com paredes de madeira tradicionais constituem um importante património cultural de muitos países, uma vez que representam uma construção anti-sísmica típica adoptada mundialmente. Portanto, a preservação dessas estruturas é de extrema importância. Embora os terremotos recentes tenham apontado o seu bom comportamento sísmico, relativamente poucos estudos experimentais estão disponíveis sobre o desempenho sísmico das paredes tradicionais. Tendo como objectivo alargar a investigação e de obter uma melhor compreensão do comportamento destes elementos construtivos (paredes de frontal em edifícios Pombalinos) sujeitos a cargas sísmicas, foi realizada uma extensa campanha experimental composta por um conjunto de ensaios cíclicos no plano em escala real de paredes de frontal. Foram consideradas paredes sem preenchimento, utilizando ligações e dimensões encontradas em estruturas reais e considerando os diferentes tipos de enchimento (alvenaria de tijolo e fasquio). Por outro lado, considerando os possíveis danos causados em caso de terremoto, após os ensaios, as paredes foram reforçadas e ensaiadas novamente para comparar a eficácia das soluções de reforço em termos de carga máxima, ductilidade, rigidez cíclica, dissipação de energia e de amortecimento viscoso. Foram adoptadas técnicas de reforço tradicionais e também inovadoras, nomeadamente parafusos, chapas de aço e barras de aço inseridas ao nível das ligações. Além disso, uma vez que o comportamento das paredes é controlado pelas suas ligações, foram realizados ensaios cíclicos no plano e ensaios de pull-out em ligações tradicionais utilizadas nas paredes. Foram adoptadas técnicas de reforço adicionais, tais como parafusos auto-perforantes e folhas de fibra de vidro, para superar algumas limitações encontradas durante os ensaios cíclicos das paredes. A partir dos resultados experimentais, foi derivado um modelo de histerese analítico, com base na modificação de modelos existentes e calibrado com base em resultados experimentais. Este modelo pode ser utilizado em modelos numéricos simplificados para representar a resposta de histerese das paredes. Finalmente, foram realizadas análises numéricas em paredes de frontal com e sem preenchimento. Os modelos foram calibrados com os resultados experimentais. Foram realizadas análises paramétricas tendo em conta diferentes variáveis.
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Coughlan, Cian, and 柯祁恩. "Seismic Behaviour of RC Flexural Walls using High Strength Materials." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/91321425782198512534.
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碩士國立臺灣大學
土木工程學研究所
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In areas of high seismicity, a common and efficient method for resisting lateral loads is by incorporating a structural wall in the building design. Structural walls can provide sufficient strength, stiffness and deformation capacity when proportioned and detailed correctly. To achieve more efficient, economical and reliable designs, it is important to understand the response and behaviour of structural walls. With the use of high-strength materials becoming increasingly popular, the need for analytical methods for predicting behaviour and deformation capacity of high-strength structural walls is crucial. Two high-strength material flexural walls were constructed and tested under reversed cyclic lateral loading. Based on observations of recent earthquakes in Chile and New Zealand, a number of researchers felt that the current ACI 318-11 standards may have some deficiencies with regards to the structural wall provisions. This study aimed to compare the performance of two specimens, one of which was designed and detailed according to the current provisions, and the second in accordance with the proposed code change requirements for the next series of ACI 318, ACI 318-14. However, due to the premature fracturing of longitudinal steel, large inelastic strains in the confining steel were not developed and a definitive conclusion could not be made. Also in this study, the current ACI recommendations for the effective stiffness used when calculating lateral displacements is evaluated and compared with the experimental results. It was found that the code recommendations overestimated the wall stiffness by over 40%. This result suggests that further research into the stiffness degradation of members constructed with high-strength material is necessary Simplified computational methods to estimate the force-displacement response of a flexural wall were examined, a comprehensive fibre sectional analysis and basic bilinear stiffness relationships were considered. The results showed that the response of the high-strength walls can be predicted effectively.
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[Verfasser], Werasak Raongjant. "Seismic behaviour of lightweight reinforced concrete shear walls / von Werasak Raongjant." 2007. http://d-nb.info/986430730/34.
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Allahvirdizadeh, Reza. "Modelling of the seismic behaviour of TRM-strengthened rammed earth walls." Master's thesis, 2017. http://hdl.handle.net/1822/54582.
Full textAbstract:
Dissertação de mestrado em Structural Analysis of Monuments and Historical ConstructionsEarthen constructions constitute a considerable part of the existing heritage and a large percentage of the World population is still living or working in buildings built with this structural system. Like other types of masonry structures, rammed earth constructions are acceptably stable under gravity loads, although they are significantly vulnerable to earthquakes. Therefore, a precise understanding of their behavior in case of being subjected to ground motions and the proposing of effective strengthening techniques achieved a great interest both in research and practice. Strengthening methods should be not only to enhance capacity and ductility of the building, but also to satisfy a variety of criteria such as being compatible with the substrate, economical and reversible. Considering all, the low-cost textile reinforced mortar (LC-TRM) strengthening is introduced, and its efficiency on rammed earth walls is studied numerically in the present thesis. In the current study, the seismic performance of both unstrengthened and strengthened rammed earth structural components is investigated. In this regard, in-plane and out-of-plane behaviors are studied by means of different constructed nonlinear finite element models. At first, pushover analysis by massbased lateral load pattern is conducted on unstrengthened walls to evaluate their capacity and understand possible failure mechanisms. Furthermore, the outcomes of these analyses are employed to select the most proper modeling approach from shell or solid elements and the walls with appropriate geometrical dimensions. In the following, pushover analyses are conducted on strengthened walls to choose between different strengthening materials and assess the effectiveness of the adopted strengthening technique. Furthermore, the frequency change of the walls with the damage states (lateral displacement levels) is studied to represent the initiation and propagation of damage in unstrengthened walls and to evaluate the effectiveness of TRM strengthening method. Finally, an artificially generated ground motion record was applied to both unstrengthened and strengthened walls to perform nonlinear time-history analyses. The outcomes were used to compare the dynamic behavior of the walls against the results of the pushover analyses.
As construções de terra constituem uma parte considerável do património construído e uma grande parte da população mundial ainda vive ou trabalha em edifícios construídos com este sistema estrutural. Como outros tipos de estruturas de alvenaria, as construções de terra são estáveis face a cargas gravíticas, embora sejam significativamente vulneráveis a sismos. Portanto, a compreensão do seu comportamento perante a ocorrência de movimentos do solo e a proposta de técnicas efetivas de reforço despertam um grande interesse, tanto a nível da investigação como na prática. Os métodos de reforço devem ser adequados não só para aumentar a capacidade e a ductilidade da construção, mas também para satisfazer uma variedade de critérios, como a compatibilidade com o substrato, custo económico e reversibilidade. Considerando todos estes aspetos, apresenta-se uma técnica baseada em argamassa reforçada com malhas têxteis de baixo custo (LC-TRM), cuja eficiência em paredes de terra é estudada na presente tese do ponto de vista numérico. No presente trabalho, investiga-se o desempenho sísmico de componentes estruturais de taipa não reforçados e reforçados. A este respeito, estudam-se os comportamentos no plano e fora do plano, por meio de diferentes modelos de elementos finitos não lineares. Em primeiro lugar, realiza-se a análise pushover proporcional à massa em paredes não reforçadas para avaliar sua capacidade e compreender possíveis mecanismos de colapso. Adicionalmente, estes resultados são utilizados para selecionar a técnica de modelação mais apropriada (elementos de casca ou sólidos) e as dimensões geométricas mais apropriadas. De seguida, realiza-se a análise pushover em paredes reforçadas para escolher de entre diferentes materiais de reforço e avaliar a eficácia da técnica de reforço adotada. Além disso, a variação das frequências das paredes com os estados de dano (níveis de deslocamento lateral) é estudada para identificar o início e a propagação de dano em paredes não reforçadas e avaliar a estabilidade do método de reforço baseado na técnica TRM. Finalmente, selecionou-se um registro sísmico artificial para realizar análises temporais não lineares de paredes simples e reforçadas. Os resultados são utilizados para comparar o comportamento dinâmico das paredes com os resultados da análise pushover.
This present work was developed within the framework of SAHC Erasmus Mundus Master Course (www.msc-sahc.org) and the project of POCI-01-0145-FEDER-016737 (PTDC/ECM-EST/2777/2014), financed by FEDER funds through the Competitivity Factors Operational Programme - COMPETE and by national funds through FCT – Foundation for Science and Technology. They are both kindly acknowledged.