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1
Apostolopoulos, Charis, Argyro Drakakaki e Maria Basdeki. "Seismic assessment of RC column under seismic loads". International Journal of Structural Integrity 10, n. 1 (4 febbraio 2019): 41–54. http://dx.doi.org/10.1108/ijsi-02-2018-0013.
Testo completoAbstract (sommario):
PurposeAs it is widely known, corrosion is a major deterioration factor for structures which are located on coastal areas. Corrosion has a great impact on both the durability and seismic performance of reinforced concrete structures. In the present study, two identical reinforced concrete columns were constructed and mechanical tests were organized to simulate seismic conditions. Prior to the initiation of the mechanical tests, the base of one of the two columns was exposed to predetermined accelerated electrochemical corrosion (at a height of 60 cm from the base). After the completion of the experimental loading procedure, the hysteresis curves – for unilateral and bilateral loadings – of the two samples were presented and analyzed (in terms of strength, displacement and dissipated energy). The paper aims to discuss this issue.Design/methodology/approachIn the present study, two identical reinforced concrete columns were constructed and mechanical tests were organized to simulate seismic conditions. The tests were executed under the combination of a constant vertical force with horizontal, gradually increasing, cyclic loads. The implemented displacements, of the free end of the column, ranged from 0.2 to 5 percent. Prior to the initiation of the mechanical tests, the base of one of the two columns was exposed to predetermined accelerated electrochemical corrosion (at a height of 60 cm from the base). After the completion of the experimental loading procedure, the hysteresis curves of the two samples were presented and analyzed (in terms of strength, displacement and dissipated energy).FindingsAnalyzing the results, for both unilateral and bilateral loadings, a significant reduction of the seismic performance of the corroded column was highlighted. The corrosion damage imposed on the reference column resulted in the dramatic decrease of its energy reserves, even though an increase in ductility was recorded. Furthermore, more attention was paid to the consequences of the uneven corrosion damage, recorded on the steel bars examined, on ductility, hysteretic behavior and damping ratio.Originality/valueIn the present paper, the influence of the corrosion effects on the cyclic response of structural elements was presented and analyzed. The simulation of the seismic conditions was achieved by imposing, at the same time, a constant vertical force and horizontal, gradually increasing, cyclic loads. Finally, an evaluation of the performance of a column, under both unilateral and bilateral loadings, took place before and after corrosion.
2
Pham, Vi Van, Anh Ngoc Do, Hung Trong Vo, Daniel Dias ., Thanh Chi Nguyen e Do Xuan Hoi. "Effect of soil Young’s modulus on Sub-rectangular tunnels behavior under quasi-static loadings". Journal of Mining and Earth Sciences 63, n. 3a (31 luglio 2022): 10–21. http://dx.doi.org/10.46326/jmes.2022.63(3a).02.
Testo completoAbstract (sommario):
Tunnels are an important component of the transportation and utility system of cities. They are being constructed at an increasing rate to facilitate the need for space expansion in densely populated urban areas and mega-cities. The circular and rectangular tunnels cannot completely meet the requirements of underground space exploitation regarding the cross-section. Sub-rectangular tunnels are recently used to overcome some drawbacks of circular and rectangular tunnels in terms of low utilization space ratio and stress concentration, respectively. However, the behavior of the sub-rectangular tunnels under seismic loading is still limited. This need to be regarded and improved. This paper focuses on conducting a numerical analysis to study the behavior of the sub-rectangular tunnels under seismic loadings. Here seismic loadings in this study are represented by quasi-static loadings. Based on the numerical model of the circular tunnel that was validated by comparison with analytical solutions, the numerical model of the sub-rectangular tunnel is created. This paper is devoted to highlight the differences between the behavior of the sub-rectangular tunnels compared with the circular ones subjected to quasi-static loadings. The soil-lining interaction, i.e., full slip and no-slip conditions are particularly considered. The influence of soil’s Young’s modulus on the sub-rectangular tunnel behavior under quasi-static loading is also investigated. The results indicated that soil’s Young’s modulus significantly affects static, incremental, and total internal forces in the tunnel lining under quasi-static loadings. Special attention is a significant difference in total internal forces in the sub-rectangular tunnel lining in comparison with the circular tunnel ones and the stability of the lining tunnel for both the full slip and no-slip conditions when subjected to quasi-static loadings.
3
Al Azem, Raneem, Wael Elleithy, Teck Leong Lau e Mohammed Parvez Anwar. "Parametric study of tensegrity structures under seismic loading". E3S Web of Conferences 347 (2022): 03016. http://dx.doi.org/10.1051/e3sconf/202234703016.
Testo completoAbstract (sommario):
Tensegrity structures are spatial structures made up of an assembly of pin-jointed, prestressed continuous tension members and discontinuous compressive members, arranged in different complex shapes. Limited research has been carried out to analyse the dynamic response of these structures under seismic loading. This paper presents a parametric study to identify the suitability of different forms of these structures under combined vertical gravity and lateral seismic loadings. Different tensegrity shapes were analysed, as simplex and complex structures, under wind and earthquake loadings. These responses of the structures were also compared to that of conventional steel structures of the same shapes. Different parameters such as the effect of varying bar diameter, bar thickness, cable diameter, and tower height, were studied, and behavioural trends were identified. It was found that if a suitable tensegrity shape is chosen and optimized, its behavioural trends can be very similar to that of the conventional steel structures, while saving materials and therefore cost. Modal frequencies of the structure were also identified and found to be low, which is beneficial under earthquake loading. Thus, these systems can prove to be a valuable replacement to conventional systems under adverse dynamic loading.
4
Zhang, Kun, Hui Li, Zhong Dong Duan e Siu Seong Law. "Identification of Multi-Axial Seismic Loadings from Several Structural Dynamic Responses". Applied Mechanics and Materials 204-208 (ottobre 2012): 2483–87. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.2483.
Testo completoAbstract (sommario):
A new method is proposed to identify multi-axial seismic loadings from structural dynamic responses on limited degrees of freedom. The seismic loadings acting on structures are modeled by Hartley series approximation, and the sensitivities of structural dynamic response with respect to the unknown approximation coefficients are derived. The identification equation is set up based on best fitting structural measured and calculated responses, and is solved with the damped least-squares method. A five-story three-dimensional steel frame structure excited by El-Centro seismic accelerations is studied for validating the proposed method. Numerical simulations with measurement noise and model errors show that the proposed method can accurately identify all seismic loadings from only several responses of the structure.
5
Matuschka, T., K. R. Berryman, A. J. O'Leary, G. H. McVerry, W. M. Mulholland e R. I. Skinner. "New Zealand seismic hazard analysis". Bulletin of the New Zealand Society for Earthquake Engineering 18, n. 4 (31 dicembre 1985): 313–22. http://dx.doi.org/10.5459/bnzsee.18.4.313-322.
Testo completoAbstract (sommario):
The results of a seismic hazard analysis for the country by the Seismic Risk Subcommittee (SRS) of the Standards Association are presented. The SRS was formed in 1979 to advise the Standards Association Loadings Code Amendments Committee on the frequency and level of earthquake ground shaking throughout New Zealand.
Results of the SRS study are in terms of estimates of five percent damped horizontal acceleration response spectra for 50, 150, 450 and 1000 year return periods. It is intended that these results will form the basis for developing seismic design response spectra for the proposed new Loadings Code (NZS 4203).
6
Hutchinson, G., J. Wilson, L. Pham, I. Billings, R. Jury e A. King. "Developing a common Australasian Earthquake Loading Standard". Bulletin of the New Zealand Society for Earthquake Engineering 28, n. 4 (31 dicembre 1995): 288–93. http://dx.doi.org/10.5459/bnzsee.28.4.288-293.
Testo completoAbstract (sommario):
The development of a common Earthquake Loading Standard for Australia and New Zealand which has the potential for most countries in SE Asia is discussed in this paper. An historical perspective of earthquake loading standards in the two countries is introduced for background. In addition, two internationally recognised standards, Uniform Building Code (UBC) and Eurocode 8, covering earthquake loadings for areas of both low and high seismicity are presented. A seismic zoning scheme similar to the UBC approach is tentatively suggested for describing the seismic hazard of Australia and New Zealand. It is suggested that the requirements for design and detailing could vary from nominal tying together to capacity design procedures for the lowest and highest seismic zones respectively.
7
Calvi, G. Michele, Gregory R. Kingsley e Guido Magenes. "Testing of Masonry Structures for Seismic Assessment". Earthquake Spectra 12, n. 1 (febbraio 1996): 145–62. http://dx.doi.org/10.1193/1.1585872.
Testo completoAbstract (sommario):
The experimental evaluation of strength, deformability, and energy dissipation capacity of unreinforced masonry buildings subjected to seismic loadings presents unique and complex problems, both for laboratory and field evaluations. The paper addresses these problems, focusing on the relative merits and roles of several experimental techniques, including quasistatic, dynamic, and pseudodynamic loadings at full and reduced scale.
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Zhang, Jian, Guo-Kai Yuan, Songye Zhu, Quan Gu, Shitang Ke e Jinghua Lin. "Seismic Analysis of 10 MW Offshore Wind Turbine with Large-Diameter Monopile in Consideration of Seabed Liquefaction". Energies 15, n. 7 (30 marzo 2022): 2539. http://dx.doi.org/10.3390/en15072539.
Testo completoAbstract (sommario):
With the increasing construction of large-scale wind turbines in seismically active coastal areas, the survivability of these high-rated-power offshore wind turbines (OWTs) in marine and geological conditions becomes extremely important. Although research on the dynamic behaviors of OWTs under earthquakes has been conducted with consideration of the soil-structure interaction, the attention paid to the impact of earthquake-induced seabed liquefaction on OWTs supported by large-diameter monopiles remains limited. In view of this research gap, this study carries out dynamic analyses of a 10 MW OWT under combined wind, wave, and earthquake loadings. This study uses a pressure-dependent multisurface elastoplastic constitutive model to simulate the soil liquefaction phenomenon. The results indicate that the motion of the large-diameter monopile leads to more extensive soil liquefaction surrounding the monopile, specifically in the zone near the pile toe. Moreover, compared with earthquake loading alone, liquefaction becomes more severe under the coupled wind and earthquake loadings. Accordingly, the dynamic responses of the OWT are apparently amplified, which demonstrates the importance of considering the coupling loadings. Compared with wind loading, the effect of wave loading on the dynamic response and liquefaction potential is relatively insignificant.
9
Yuksel, Tugce, Yalcin Yuksel, Busra Basaran e Esin Cevik. "DETERMINATION OF CROSS SECTIONS FOR GRAVITY TYPE QUAY WALLS". Coastal Engineering Proceedings, n. 35 (23 giugno 2017): 5. http://dx.doi.org/10.9753/icce.v35.structures.5.
Testo completoAbstract (sommario):
Block type quay walls are widely used as port structures in the world. In this study three types of vertical block type quay walls with different block size exposed to seismic loading were investigated experimentally. The block ratios of Type I, Type II and III vertical wall models are B/h=2, 1.5 and 1.5 & H/h=6, 6 and 3, respectively. The tests were conducted in the shaking tank with different harmonic seismic loadings and the behaviors of these walls were investigated comparatively.
10
Behr, Richard A., e Abdeldjelil Belarbi. "Seismic Test Methods for Architectural Glazing Systems". Earthquake Spectra 12, n. 1 (febbraio 1996): 129–43. http://dx.doi.org/10.1193/1.1585871.
Testo completoAbstract (sommario):
An ongoing effort is being made at the University of Missouri-Rolla to develop standard laboratory test methods and codified design procedures for architectural glass under seismic loadings. Recent laboratory work has yielded some promising results regarding the development of an appropriate seismic test method for architectural glass, as well as identifying ultimate limit states that quantify the seismic performance and damage thresholds of various glass types. Specifically, a straightforward “crescendo-like” in-plane dynamic racking test, performed at a constant frequency, has been employed successfully. Two ultimate limit states for architectural glass have been defined: (1) a lower ultimate limit state corresponding to major glass crack pattern formation; and (2) an upper limit state corresponding to significant glass fallout. Early crescendo tests have yielded distinct and repeatable ultimate limit state data for various storefront glass types tested under dynamic racking motions. Crescendo tests will also be used to identify and quantify serviceability limit states for architectural glass and associated glazing components under dynamic loadings. These limit state data will support the development of rational design procedures for architectural glass under seismic loadings.
11
Xu, Shiqing. "Recognizing fracture pattern signatures contributed by seismic loadings". Interpretation 8, n. 4 (23 luglio 2020): SP95—SP108. http://dx.doi.org/10.1190/int-2020-0033.1.
Testo completoAbstract (sommario):
The impacts of seismic loadings to fault zone rocks still are not well understood. Although field and experimental studies have suggested several markers, such as pseudotachylytes and pulverized rocks, for indicating seismic loadings, the corresponding markers of other types or at larger scales still are lacking. Drawing from the results of dynamic ruptures with off-fault damage, we have recognized several additional fracture features that may be used to reflect the involvement of seismic loadings. For strike-slip faults stressed at moderate to high angles, synthetic R shear is more favored during rupture propagation, but pronounced antithetic R′ shear can be generated around the termination end of the rupture. In addition, suitably oriented weak structures off the main fault can further facilitate the activation of R′ shear. For low-angle thrust faults such as subduction zones, splay faults in the form of forethrusts and backthrusts still can be generated above the coseismic rupture zone. These faults show an increased spatial extent toward the updip direction, effectively defining an outer wedge susceptible to pervasive compressional failure over its entire depth range. Moreover, a deeply nucleated megathrust rupture that eventually reaches the trench can sequentially load the frontal wedge in compression and then in extension, with the potential to leave a mixture of triggered reverse and normal faults at the final stage. Because the above results also are supported by many observations, they raise a caution that existing fault models ignoring dynamic effects should be used with care and that seismic loadings must be considered more seriously by future fault zone studies.
12
Wu, Guo Xiong, Xiang Shou Chen, Jing Sheng Ding e Wang Fei Ding. "Determination of Critical Height of Slope Filled by Red-Bed Soft Rock under Seismic Loading". Advanced Materials Research 261-263 (maggio 2011): 1655–59. http://dx.doi.org/10.4028/www.scientific.net/amr.261-263.1655.
Testo completoAbstract (sommario):
The combined influence of the earthquakes and the widespread red-bed soft rock as fill material necessitates the increasing attention on the slope stability in the west region of Yunnan province. To determine the critical height of slope filled by such soft rock under seismic loading, this paper establishes a model simulating a fill slope based on the finite element method and the strength reduction theory. The influence of different slope configurations, including different slope ratios, heights, and side forms on the slope stability is analyzed, and with the stability factor equal or greater than 1.1 as designated in the specifications, the slope critical heights are back calculated. The results show: (1)seismic loading has a significant influence on the slope stability, although its decreasing magnitude slows down with the increase of the slope height.; (2)the fill slope 16m in height is most instable under seismic loading, so the slope at or greater than 16m high is not recommended; (3)whatever the loading forms on the slope, either under the gravity loading only or the combined gravity and seismic loadings, the linear slope is most instable, with increasing stability for concave and step slopes.
13
Li, Yong, Ye Liu e Shaoping Meng. "Seismic performance evaluation of coupled wall system with novel replaceable steel truss coupling beams". Advances in Structural Engineering 22, n. 6 (18 novembre 2018): 1284–96. http://dx.doi.org/10.1177/1369433218811530.
Testo completoAbstract (sommario):
Coupled wall systems are often used in high-rise buildings in zone of high seismic risk to provide lateral resistance to earthquake loading. Once damaged, reinforced concrete coupling beams are costly and time-consuming to repair post-earthquake. To enhance the seismic resilience for coupled wall structures, a novel replaceable steel truss coupling beam is first introduced. The proposed replaceable steel truss coupling beam consists of chord members at the top and bottom, respectively, and two buckling-restrained energy dissipaters are employed in the diagonal direction. The energy dissipaters can yield first before the wall piers and dissipate large amounts of energy to protect the main structure under seismic loadings. In addition, the energy dissipaters can be easily installed and post-earthquake repaired through pin connection with the chord members. This article mainly focused on the numerical and theoretical analyses of the proposed replaceable steel truss coupling beam, and nonlinear analytical models were developed in PERFORM-3D. An 11-story prototype structure was designed per Chinese code. The seismic response of hybrid coupled wall system with replaceable steel truss coupling beams was evaluated using nonlinear time history analysis and compared with the response of reinforced concrete coupled wall system with reinforced concrete coupling beams under seismic loadings. Results show that the proposed replaceable steel truss coupling beam leads to a good seismic response with reduced interstory drifts of the systems and rotational demand in the beams and wall piers due to a large energy dissipation capacity and overstrength.
14
Thurston, Stuart J., e Stuart G. Park. "Seismic design of New Zealand houses". Bulletin of the New Zealand Society for Earthquake Engineering 37, n. 1 (31 marzo 2004): 1–12. http://dx.doi.org/10.5459/bnzsee.37.1.1-12.
Testo completoAbstract (sommario):
This paper presents the basis for changing the current test and evaluation procedure used to establish bracing ratings. This is known as the BRANZ P21 test method and is used to obtain the bracing ratings of timber framed wall systems for houses, and other low-rise structures, to meet the wind and seismic demand stipulated in the light timber framing standard, NZS 3604:1999. The demand seismic loads in NZS 3604 were based on the loadings specified in the New Zealand loadings standard, NZS 4203:1992. This paper proposes a revised P21 test seismic evaluation (called EM3) so that houses constructed to NZS3604 do not exceed their wall deformation capacity when analysed against a suite of earthquake records compatible with NZS 4203:1992.
15
Wang, Chang Qing. "Investigation on Seismic Behavior of Recycled Aggregate Concrete Structures under Dynamic Loadings". Advanced Materials Research 772 (settembre 2013): 149–55. http://dx.doi.org/10.4028/www.scientific.net/amr.772.149.
Testo completoAbstract (sommario):
Based on the ever finished investigations of physical and mechanical properties of recycled aggregate concrete (RAC), and a series of experimental studies on the durability, the fatigue behavior, mechanical behavior and the seismic behavior of RAC components. A full scale model of a one-storey block masonry structure with tie column + ring beam + cast-in-place slab system and a one fourth scaled model of a 6-storey frame structure, which are made of reinforced recycled aggregate concrete, are tested on a shaking table by subjecting it to a series of simulated seismic ground motions, and the seismic behaviors of the RAC structures were experimentally investigated. The dynamic characteristics and the seismic response were analyzed and discussed. The overall seismic performance of RCA structures are evaluated, the analysis results show that the recycled aggregate concrete structures with proper design exhibits good seismic behavior and can resist the earthquake attacks under different earthquake levels in this study. It is feasible to apply and popularize the RAC block masonry buildings less than 2 stories and the RAC frame buildings less than 6 stories in the region where the seismic fortification intensity is 8.
16
Fenwick, Richard, David Lau e Barry Davidson. "A comparison of the seismic design requirements in the New Zealand Loadings Standard with other major design codes". Bulletin of the New Zealand Society for Earthquake Engineering 35, n. 3 (30 settembre 2002): 190–203. http://dx.doi.org/10.5459/bnzsee.35.3.190-203.
Testo completoAbstract (sommario):
A series of ductile moment resisting reinforced concrete frames are sized to meet the minimum seismic provisions of the New Zealand Loadings Standard, NZS 4203-1992, the Draft NZ/Australian Loadings Standard, the Uniform Building Code, UBC-1997, the International Building code, IBC 2000 (1998 draft) and Eurocode 8 (1998 draft). The results of the analyses allow valid comparisons to be made between the different codes. It is shown that comparisons of individual clauses can be misleading due to the many interactions that occur between clauses.
Comparative analyses were made for the buildings described above located in both high and low seismic regions. It is shown that the strength and stiffness requirements for both the New Zealand Loadings Standard and the Draft Standard are low compared with the other codes of practice in the high seismic zone. It is recommended that the required design strengths in the Draft NZ/Australian Standard be increased.
17
Chiang, J. C. L., e Leong Wai Lim. "Behaviour and Strengthening Methods of Tall Slender Columns in Earthquake Conditions". Key Engineering Materials 879 (marzo 2021): 221–31. http://dx.doi.org/10.4028/www.scientific.net/kem.879.221.
Testo completoAbstract (sommario):
Reinforced concrete buildings are normally designed and constructed with well-defined vertical column supports which are able to withstand both vertical and lateral loadings. In the case of high columns there is a risk of instability due to its slenderness caused by the higher apex ratio (measured by its height in relation to the width). This is compounded by having such buildings located at medium to high seismic risk zones, where lateral dynamic loadings can occur. This research paper focused on how such slender reinforced concrete columns will behave under earthquake loading conditions, and highlights some innovative ways to strengthen the column capacity to withstand both vertical and lateral loadings. Besides the conventional ways to provide diagonal or lateral bracings, the use of glass fibre reinforced polymer (GFRP) as an alternative material for retrofitting tall slender reinforced concrete columns are presented here. The new method includes spraying of the GFRP onto the external surfaces of the columns and also incorporate the GFRP bars as additional reinforcement into the concrete columns. Both methods proved to improve the durability and strengthen the tall reinforced concrete column. This study shows the ability of the new method of amelioration of the slender reinforced concrete columns to increase their stability during seismic activity.
18
Abarkane, Chihab, Francisco J. Rescalvo, Jesús Donaire-Ávila, David Galé-Lamuela, Amadeo Benavent-Climent e Antolino Gallego Molina. "Temporal Acoustic Emission Index for Damage Monitoring of RC Structures Subjected to Bidirectional Seismic Loadings". Materials 12, n. 17 (30 agosto 2019): 2804. http://dx.doi.org/10.3390/ma12172804.
Testo completoAbstract (sommario):
This paper shows the acoustic emission (AE) analysis recorded during the loading process of reinforced concrete (RC) structures subjected to bidirectional seismic loadings. Two waffle plates (bidirectional) supported by isolated square columns were tested on a shaking table with a progressive and increasing ground acceleration until the final collapse. Each specimen was subjected to a different loading history. A relevant delay in the beginning of the significant AE energy is observed as the peak value of the ground acceleration increases. Based on this result, a new AE temporal damage index (TDI), defined as the time difference between the onset of the significant AE activity and the onset of the loading that causes this AE activity, is proposed and validated by comparing it with the plastic strain energy released by the concrete, typically used as a reliable damage level indicator. Good agreement was observed for both specimens and seismic inputs.
19
Izhar, M. S., M. Umair e M. I. Ansari. "Damage Assessment of Reinforced Concrete Bridges Under the Ground Motions - a Probabilistic Approach". Journal of Applied Engineering Sciences 12, n. 2 (1 dicembre 2022): 179–84. http://dx.doi.org/10.2478/jaes-2022-0024.
Testo completoAbstract (sommario):
Abstract Bridges are important structures for urban civilization. The catastrophic damage to bridges during an earthquakes cause sudden disruption to human livelihood. For making bridges resilient to earthquakes proper damage assessment technique is inevitable. The present study has been carried out to evaluate damage of reinforced concrete bridge under the seismic loadings using a probabilistic approach. Nine earthquakes were considered for seismic vulnerability assessment. From the obtained results, different damage states were discussed based on intensity measures using Incremental Dynamic Analysis (IDA) and Fragility Analysis. This study may be used as a viable tool for health monitoring, vulnerability assessment and formulating retrofit strategies of the reinforced concrete bridges under the seismic loadings.
20
Maison, Bruce F., e Matthew S. Speicher. "Loading Protocols for ASCE 41 Backbone Curves". Earthquake Spectra 32, n. 4 (novembre 2016): 2513–32. http://dx.doi.org/10.1193/010816eqs007ep.
Testo completoAbstract (sommario):
ASCE 41 is the industry standard for seismic evaluation and retrofit of existing buildings. It allows for alternative component modeling and acceptance criteria based on a backbone curve constructed from envelopes of component hysteresis loops derived via experimental cyclic tests. ASCE 41-13 requires use of loading protocols having fully reversed cyclic loadings with increasing displacement levels. However, recent research summarized herein indicates the need for inclusion of different protocols that pay specific attention to behavior incipient to collapse. This view is supported by example building computer earthquake response simulations described herein. A generalized loading pattern derived from the simulations found relatively few drift excursions having one-direction bias, suggesting one-sided cyclic and/or monotonic tests may be better for describing building inelastic seismic demands.
21
Herrera, Daniel, Gerardo Varela e Dante Tolentino. "Reliability Assessment of RC Bridges Subjected to Seismic Loadings". Applied Sciences 12, n. 1 (25 dicembre 2021): 206. http://dx.doi.org/10.3390/app12010206.
Testo completoAbstract (sommario):
An approach to estimate both the reliability index β and its complement, the probability of failure, through closed-form expressions that consider aleatory and epistemic uncertainties, is proposed. Alternatively, exceedance demand rates are obtained based on simplified expressions and numerical integration. Reliability indicators are calculated, considering the uncertainties in the compressive strength of concrete, steel yield, and section geometry, together with the aleatory uncertainties related to seismic loadings. Such indicators are estimated in a continuous RC bridge located in Acapulco, Guerrero, Mexico. The bridge was designed to comply with a drift of 0.004. Exceedance demand rates for drift thresholds from 0.001 to 0.012 are estimated, and maximum differences of 5.5% are found between the closed-form expression and numerical integration. The exceedance demand rate expressed by means of its inverse, the return period, indicates that the serviceability limit state is exceeded after 58 years of the bridge construction. The reliability index decreases by about 1.66%, and the probability of failure increases by about 16.1% when the epistemic uncertainties are considered. The approach shows the importance of epistemic uncertainties in the estimation of reliability indicators.
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Tan, Robert Y., e S. M. Chen. "The performance of water transmission systems under seismic loadings". Soil Dynamics and Earthquake Engineering 6, n. 3 (luglio 1987): 149–57. http://dx.doi.org/10.1016/0267-7261(87)90011-x.
Testo completo
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Hemmati, Arash, e Erkan Oterkus. "Semi-Active Structural Control of Offshore Wind Turbines Considering Damage Development". Journal of Marine Science and Engineering 6, n. 3 (5 settembre 2018): 102. http://dx.doi.org/10.3390/jmse6030102.
Testo completoAbstract (sommario):
High flexibility of new offshore wind turbines (OWT) makes them vulnerable since they are subjected to large environmental loadings, wind turbine excitations and seismic loadings. A control system capable of mitigating undesired vibrations with the potential of modifying its structural properties depending on time-variant loadings and damage development can effectively enhance serviceability and fatigue lifetime of turbine systems. In the present paper, a model for offshore wind turbine systems equipped with a semi-active time-variant tuned mass damper is developed considering nonlinear soil–pile interaction phenomenon and time-variant damage conditions. The adaptive concept of this tuned mass damper assumes slow change in its structural properties. Stochastic wind and wave loadings in conjunction with ground motions are applied to the system. Damages to soil and tower caused by earthquake strokes are considered and the semi-active control device is retuned to the instantaneous frequency of the system using short-time Fourier transformation (STFT). The performance of semi-active time-variant vibration control is compared with its passive counterpart in operational and parked conditions. The dynamic responses for a single seismic record and a set of seismic records are presented. The results show that a semi-active mass damper with a mass ratio of 1% performs significantly better than a passive tuned mass damper with a mass ratio of 4%.
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Shah, Mati Ullah, e Muhammad Usman. "An experimental study of tuned liquid column damper controlled multi-degree of freedom structure subject to harmonic and seismic excitations". PLOS ONE 17, n. 6 (13 giugno 2022): e0269910. http://dx.doi.org/10.1371/journal.pone.0269910.
Testo completoAbstract (sommario):
A tuned liquid column damper (TLCD) is a passive vibration control device that not only mitigates unwanted structural vibrations but also acts as a water storage facility in a building. These aspects of TLCD make its application specifically suited for building structures. Previously, many experimental works on TLCDs have been conducted considering a single degree of freedom (SDOF) structure. However, the performance of TLCDs to control the response of multi-degree of freedom (MDOF) structure has rarely been studied experimentally. Therefore, this study has investigated the performance of a tuned liquid column damper (TLCD) on a multi-degree of freedom (MDOF) structure using shake table testing. A four-storey steel frame structure equipped with TLCD at the top of the fourth storey has been studied. Experimental normalized frequency response curves for MDOF structure equipped with TLCD have been determined. For this purpose, a series of harmonic loadings including frequencies 0.65 Hz, 1.17 Hz, 1.30 Hz, 1.43 Hz and 1.95 Hz have been applied in addition to historic earthquake loading. Peak and root-mean-square (RMS) accelerations have been discussed in detail for all the applied loadings at each storey level of the structure. For comparison purposes, the percentage reductions in peak and RMS accelerations have been calculated and compared. Also, RMS displacements and inter-storey drifts have been presented for resonant and seismic excitations. Both in time and frequency domains, responses of controlled MDOF structure have been analyzed and compared with uncontrolled structure. Results confirmed that TLCD has improved the MDOF structure responses at harmonic loadings frequencies near resonance and historic earthquake excitations. Furthermore, the improvement in the responses of MDOF structure with TLCD is more prominent at harmonic loadings compared to historic earthquake loading.
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Pham, Van Vi, Ngoc Anh Do e Daniel Dias. "Sub-Rectangular Tunnel Behavior under Seismic Loading". Applied Sciences 11, n. 21 (23 ottobre 2021): 9909. http://dx.doi.org/10.3390/app11219909.
Testo completoAbstract (sommario):
Circular and rectangular tunnel shapes are usually chosen when excavating at shallow depths in urban areas. However, special-shaped tunnels such as sub-rectangular tunnels have recently been used to overcome some drawbacks of circular and rectangular tunnels in terms of low space utilization efficiency and stress concentration, respectively. In the literature, experimental studies as well as analytical and numerical models have been developed for the seismic analysis and vulnerability assessment of circular and rectangular tunnels since the early 1990s. However, knowledge gaps regarding the behavior of sub-rectangular tunnels under seismic loading remain and still need to be bridged. The present paper focuses on introducing a numerical analysis of sub-rectangular tunnels under seismic loading. The numerical model of sub-rectangular tunnels is developed based on the numerical analyses of circular tunnels validated by comparing well-known, analytical solutions. This paper aims to highlight the differences between the behavior of sub-rectangular tunnels compared with circular tunnels when subjected to seismic loadings. Special attention is paid to the soil–lining interface conditions. The influence of parameters, such as soil deformations, maximum horizontal acceleration, and lining thickness, on sub-rectangular tunnel behavior under seismic loading is also investigated. The results indicate a significant behavior difference between sub-rectangular and circular tunnels. The absolute extreme incremental bending moments for a circular tunnel (no-slip condition) are smaller than that for the corresponding full-slip condition. The absolute extreme incremental bending moments of sub-rectangular tunnels (no-slip condition) are, however, greater than the corresponding full-slip conditions.
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Ramana, P. V., Anamika Agnihotri, Ayush Meena, Engammagari Ganesh, M. K. Shrimali e S. D. Bharti. "Simulation and Soft Computation on Materials Prognostication Seismic Assessment". Proceedings of the 12th Structural Engineering Convention, SEC 2022: Themes 1-2 1, n. 1 (19 dicembre 2022): 1839–46. http://dx.doi.org/10.38208/acp.v1.726.
Testo completoAbstract (sommario):
The research paper ETABS is an integrated programming software providing mass distribution and rapid analysis of structures building where we can assign loadings per codal provision. Different methods are also available to elongate our research and analysis of the system. This software developed by CSI is also utilized in the designing of Burj khalifa. ETABS is coordinated programming giving mass dispersion and immediate investigation of building designs where one can allocate loadings according to any codal arrangement. Various strategies are additionally accessible to extend our examination and examination of construction. This paper depicts to determines the role of dampers in tall structures. To assess the stability of the system under seismic load considering dampers. To compare two distinct types of dampers to evaluate the seismic effect of different earthquakes. To provide cost analysis of form per SOR to assess the seismic impact on distant earthquakes.
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Donaire-Ávila, Jesús, e David Galé-Lamuela. "Energy Capacity of Waffle-Flat-Plate Structures with Hysteretic Dampers Subjected to Bidirectional Seismic Loadings". Applied Sciences 10, n. 9 (30 aprile 2020): 3133. http://dx.doi.org/10.3390/app10093133.
Testo completoAbstract (sommario):
This study investigates the capacity, in terms of energy, of waffle-flat-plate (WFP) structures with hysteretic dampers subjected to biaxial seismic actions. A numerical model was developed and calibrated with the experimental results obtained from shake-table testing carried out on a WFP specimen subjected to biaxial seismic loads. Then the WFP system was retrofitted with hysteretic dampers—slit-plate dampers (SPDs)—and the numerical model was subjected to different sets of ordinary ground motion records to attain different seismic performance levels (SPLs). Each set of records was applied in a sequence of scaled seismic simulations until the SPL of near collapse was achieved. The capacity in terms of input energy and dissipated energy are presented for the different SPLs, taking into account the differences observed under unidirectional and bidirectional seismic loadings. Furthermore, the level of damage (i.e., accumulated plastic deformations), the level of ductility and the relationship between them—expressed as equivalent number of cycles—are also shown for both the WFP system and the hysteretic dampers. The seismic capacity of the WFP system is found to be significantly enhanced by the inclusion of hysteretic dampers.
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Wang, Fan, Yong Yu, Xin-Yu Zhao, Jin-Jun Xu, Tian-Yu Xie e Simret Deresa. "Performance Evaluation of Reinforced Recycled Aggregate Concrete Columns under Cyclic Loadings". Applied Sciences 9, n. 7 (8 aprile 2019): 1460. http://dx.doi.org/10.3390/app9071460.
Testo completoAbstract (sommario):
Recycled concrete aggregates (RCAs) generated from construction and demolition activities have been recognized as a feasible alternative to natural aggregates (NAs). Naturally, the columns fabricated with reinforced recycled concrete (RRC) have been proposed and investigated to promote the structural use of recycled aggregate concrete (RAC). There is still, however, very limited modeling research available to reproduce, accurately and efficiently, the seismic response of RRC columns under lateral cyclic loading; proper evaluations are also lacking on addressing the columns’ seismic behaviors. To fill some of those research gaps, a fiber-based numerical model is developed in this study and then validated with the experimental results published in the literature. Subsequently, the numerical model justified is applied to carry out a comprehensive parametric study to examine the effects of a range of variables on the hysteretic characteristics of RRC columns. Furthermore, a grey relational analysis is conducted to establish quantifiable evidence of key variable sensitivities. The evaluation results imply that the use of the additional water method (AWM) for manufacturing RAC is likely to reduce the lateral load-carrying capacity of the RRC columns (up to 10%), whereas the opposite would occur if a conventional mixing procedure is adopted. Moreover, compared with other factors such as steel area ratio, the content of RCA replacement has a less remarkable effect on the seismic performance of the RRC columns. In general, the RRC columns possess acceptable seismic-resistant properties, and they can be used in earthquake-prone regions with confidence.
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Hogan, L. S., L. M. Wotherspoon e J. M. Ingham. "Development of New Zealand seismic bridge standards". Bulletin of the New Zealand Society for Earthquake Engineering 46, n. 4 (31 dicembre 2013): 201–21. http://dx.doi.org/10.5459/bnzsee.46.4.201-221.
Testo completoAbstract (sommario):
During seismic assessments of bridges where there is a lack of construction documentation, one method of determining likely structural detailing is to use historic design standards. An overview of the New Zealand bridge seismic standards and the agencies that have historically controlled bridge design and construction is presented. Standards are grouped into design era based upon similar design and loading characteristics. Major changes in base shear demand, ductility, foundation design, and linkage systems are discussed for each design era, and loadings and detailing requirements from different eras were compared to current design practices. Bridges constructed using early seismic standards were designed to a significantly lower base shear than is currently used but the majority of these bridges are unlikely to collapse due to their geometry and a preference for monolithic construction. Bridges constructed after the late 1970s are expected to perform well if subjected to ground shaking, but unless bridges were constructed recently their performance when subjected to liquefaction and liquefaction-induced lateral spreading is expected to be poor.
30
Wang, Ding, Yueliang Li, Shengwang Hao e Dahai Zhao. "Wave-Passage Effect of Earthquake Loadings on Long Structures". International Journal of Structural Stability and Dynamics 16, n. 07 (3 agosto 2016): 1550037. http://dx.doi.org/10.1142/s0219455415500376.
Testo completoAbstract (sommario):
The wave-passage effect of earthquake loadings on long-span structures is studied through use of a multiply-supported single-degree-of-freedom (SDOF) system excited by traveling seismic ground motions. The absolute acceleration response of the SDOF system is represented in the analytical form in the time domain. The frequency-domain analysis results indicate that the wave-passage effect may reduce the absolute acceleration response and the earthquake loading acting on the multiply-supported SDOF system. Further, for different velocities of wave-passage, the response spectra are calculated to represent the reduction of the maximum earthquake loading on the long-span system caused by the wave-passage effect. The computation results of the response spectra indicate that the reduction of the maximum earthquake loading is fluctuant, but has a general tendency to decrease with the increase in the apparent wave velocity and the structural natural period.
31
Jacob, Meera, e S. D. Balakrishnan. "A Review on the Combined Effects of Seismic and Vehicular Vibrations on Long Span Bridges". Proceedings of the 12th Structural Engineering Convention, SEC 2022: Themes 1-2 1, n. 1 (19 dicembre 2022): 537–43. http://dx.doi.org/10.38208/acp.v1.545.
Testo completoAbstract (sommario):
Long span bridges are massive structures which are subjected to combined loadings. The increase in span length of long span bridges will result in decrease of their natural frequencies that renders them very susceptible to the actions of various combined dynamic forces. Dynamic loads such as vehicular movement and seismic excitations have greater potential in causing increased vibrations in long span bridges. The vehicular loading is highly variable and depends on type of vehicle, number of lane, behaviour of vehicle such as lane changing, traffic congestions and so on. Further, seismic excitations are characterized by its spatial variability parameters such as incoherence effect, wave passage effect and site response effects. From detailed review, it was found that fewer researches have been carried out in the field of dynamic effects of long span arch bridges and thus the study aims in determining the combined effects of seismic and vehicular vibrations on long span arch bridges.
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Azeloglu, C. Oktay, Ayse Edincliler e Ahmet Sagirli. "Investigation of Seismic Behavior of Container Crane Structures by Shake Table Tests and Mathematical Modeling". Shock and Vibration 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/682647.
Testo completoAbstract (sommario):
This paper is concerned with the verification of mathematical modeling of the container cranes under earthquake loadings with shake table test results. Comparison of the shake table tests with the theoretical studies has an important role in the estimation of the seismic behavior of the engineering structures. For this purpose, a new shake table and mathematical model were developed. Firstly, a new physical model is directly fixed on the shake table and the seismic response of the container crane model against the past earthquake ground motion was measured. Secondly, a four degrees-of-freedom mathematical model is developed to understand the dynamic behaviour of cranes under the seismic loadings. The results of the verification study indicate that the developed mathematical model reasonably represents the dynamic behaviour of the crane structure both in time and frequency domains. The mathematical model can be used in active-passive vibration control studies to decrease structural vibrations on container cranes.
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Gupta, A., V. Yadav, V. A. Sawant e R. Agarwal. "Effect of Wall Inclination on Dynamic Active Thrust for Cohesive Soil Backfill". Journal of Civil Engineering, Science and Technology 9, n. 2 (3 ottobre 2018): 6. http://dx.doi.org/10.33736/jcest.992.2018.
Testo completoAbstract (sommario):
Design of retaining walls under seismic conditions is based on the calculation of seismic earth pressurebehind the wall. To calculate the seismic active earth pressure behind the vertical retaining wall, many researchers reportanalytical solutions using the pseudo-static approach for both cohesionless and cohesive soil backfill. Design charts havebeen presented for the calculation of seismic active earth pressure behind vertical retaining walls in the non-dimensionalform. For inclined retaining walls, the analytical solutions for the calculation of seismic active earth pressure as well as thedesign charts (in non-dimensional form) have been reported in few studies for c-ϕ soil backfill. One analytical solution forthe calculation of seismic active earth pressure behind inclined retaining walls by Shukla (2015) is used in the present studyto obtain the design charts in non-dimensional form. Different field parameters related with wall geometry, seismic loadings,tension cracks, soil backfill properties, surcharge and wall friction are used in the present analysis. The present study hasquantified the effect of negative and positive wall inclination as well as the effect of soil cohesion (c), angle of shearingresistance (ϕ), surcharge loading (q) and the horizontal and vertical seismic coefficient (kh and kv) on seismic active earthpressure with the help of design charts for c-ϕ soil backfill. The design charts presented here in non-dimensional form aresimple to use and can be implemented by field engineers for design of inclined retaining walls under seismic conditions. Theactive earth pressure coefficients for cohesionless soil backfill achieved from the present study are validated with studiesreported in the literature.
34
Wang, Qiuzhe, Jiang Bian, Wenting Huang, Qingrui Lu, Kai Zhao e Zhaoyan Li. "Seabed Liquefaction around Pipeline with Backfilling Trench Subjected to Strong Earthquake Motions". Sustainability 14, n. 19 (8 ottobre 2022): 12825. http://dx.doi.org/10.3390/su141912825.
Testo completoAbstract (sommario):
As an indispensable part of the lifeline for the offshore gas and oil industry, submarine pipelines under long-term marine environmental loadings have historically been susceptible to earthquakes. This study investigates the impact of trench backfilling on the residual liquefaction around a pipeline and the induced uplift of a pipeline under the combined action of an earthquake, ocean wave and current loading. A fully coupled nonlinear effective stress analysis method, which can consider the nonlinear hysteresis and the large deformation after liquefaction of the seabed soil, is adopted to describe the interaction between the seabed soil and the submarine pipeline. Taking a typical borehole in the Bohai strait as the site condition, the nonlinear seismic response analysis of the submarine pipeline under the combined action of seismic loading and ocean wave and current is carried out. The numerical results show that trench backfilling has a significant impact on the seismic response of the pipeline. The existence of trench backfilling reduces the accumulation of the residual excess pore water pressure, so that the seabed liquefaction around the pipeline is mitigated and the uplift of the pipeline is also decreased.
35
Kelly, Trevor E. "Tentative seismic design guidelines for rocking structures". Bulletin of the New Zealand Society for Earthquake Engineering 42, n. 4 (31 dicembre 2009): 239–74. http://dx.doi.org/10.5459/bnzsee.42.4.239-274.
Testo completoAbstract (sommario):
Many new and existing buildings have insufficient weight to resist overturning loads due to earthquakes without uplift. Previous versions of the New Zealand loadings code allowed simplified procedures for the design of rocking structures provided the ductility factor was limited to not more than two. The new loadings code, NZS 1170.5, removed this exemption and requires that a special study be performed whenever energy dissipation through rocking occurs. This paper presents a tentative design procedure intended to substitute for the special study required by the code.
The resistance function of rocking walls was developed from the principles of engineering mechanics. The results from a series of time history analyses were used to develop a procedure to estimate maximum seismic displacements and empirical equations were derived to estimate the dynamic amplification of inertia forces. A substitute structure approach, using spectral displacements at an effective period calculated from the ductility factor, provided accurate predictions of the displacements from more sophisticated nonlinear analyses.
Four example designs were completed and the predicted response compared to time history results. The procedure provided a satisfactory estimate of response for regular structures, but it was less accurate where torsional effects were significant.
36
Sahoo, P. P., e S. K. Shukla. "Time-History Analysis of Soil Slope Subjected to Seismic Loadings". Soil Mechanics and Foundation Engineering 58, n. 2 (maggio 2021): 130–37. http://dx.doi.org/10.1007/s11204-021-09717-z.
Testo completo
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Peng, Huai-sheng, Jian Deng e De-sheng Gu. "Earth slope reliability analysis under seismic loadings using neural network". Journal of Central South University of Technology 12, n. 5 (ottobre 2005): 606–10. http://dx.doi.org/10.1007/s11771-005-0131-9.
Testo completo
38
Stawniczy, G., W. R. Bak e G. Hau. "Piping Stress-Strain Correlation for Seismic Loading". Journal of Pressure Vessel Technology 110, n. 4 (1 novembre 1988): 444–50. http://dx.doi.org/10.1115/1.3265627.
Testo completoAbstract (sommario):
This paper establishes limits on piping material strains for ASME Boiler and Pressure Vessel Code Level D loadings that ensure a limitation of deformation and provide suitable safety margins. In establishing the strain limits, potential piping failure modes due to compressive wrinkling and low-cycle fatigue are considered. A stress-strain correlation methodology to convert linear, elastically calculated Code Class 2 and 3 equation (9)-Level D stresses to strains is established. This correlation is based on the fatigue evaluation procedure of the Code and is verified by comparison with test results. A detailed discussion of test results compared with the stress-strain correlation methodology is also presented.
39
He, Jian, Yu Jiang, Qichao Xue, Chunwei Zhang e Jingcai Zhang. "Energy response analysis of adjacent structures with polymer bumpers under seismic loadings". Advances in Mechanical Engineering 10, n. 12 (dicembre 2018): 168781401880915. http://dx.doi.org/10.1177/1687814018809157.
Testo completoAbstract (sommario):
Insufficient gap between adjacent buildings may lead serious poundings under seismic loadings. Installing polymer bumpers may decrease the pounding forces between colliding buildings, which can prevent column yielding from overlarge shearing forces. This article focuses on the analysis on energy responses of adjacent structures equipped with polymer bumpers. Based on a novel pounding analysis method, systematic comparisons of structural pounding performance are conducted and specific results are obtained and discussed. First, time history responses for pounding force, displacements, and yielding shearing forces in selected floors are calculated. Then, energy response analysis considering viscoelasticity of bumpers is investigated. Afterward, under different seismic waves, input energy response, pounding force procedures, and story displacements are studied and discussed. And finally, parametric studies on energy responses, including gaps, sizes, and viscoelasticity parameters, are carried out to investigate influence sensitiveness of bumper parameters. The results show that the novel viscoelastic pounding force model is effective in simulating and calculating adjacent structural pounding with polymer bumpers. Although, in many cases, viscoelasticity has little effect on pounding forces and energy response time histories, it still has certain influences on maximum values. And, equipping with polymer bumpers on adjacent buildings can decrease maximum pounding forces under all types of seismic waves, but pounding times and maximum displacements of stories increase after being equipped with bumpers. By comparing cases under different seismic waves, energy responses show sensitive characteristics to different earthquake waves. Besides, gaps, sizes of bumpers also have significant influence on energy performance. They affect peak yielding energy and peak damping energy significantly.
40
McCormick, Jason, Reginald DesRoches, Davide Fugazza e Ferdinando Auricchio. "Seismic Vibration Control Using Superelastic Shape Memory Alloys". Journal of Engineering Materials and Technology 128, n. 3 (3 aprile 2006): 294–301. http://dx.doi.org/10.1115/1.2203109.
Testo completoAbstract (sommario):
Superelastic NiTi shape memory alloy (SMA) wires and bars are studied to determine their damping and recentering capability for applications in the structural control of buildings subjected to earthquake loadings. These studies improve the knowledge base in regard to the use of SMAs in seismic design and retrofit of structures. The results show that the damping properties of austenitic SMAs are generally low. However, the residual strain obtained after loading to 6% strain is typically <0.75%. In general, it is shown that large diameters bars perform as well as wire specimens used in non-civil-engineering applications. The results of a small-scale shake table test are then presented as a proof of concept study of a SMA cross-bracing system. These results are verified through analytical nonlinear time history analysis. Finally, a three-story steel frame implementing either a traditional steel buckling-allowed bracing system or a SMA bracing system is analyzed analytically to determine if there is an advantage to using a SMA bracing system. The results show that the SMA braces improve the response of the braced frames.
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Dar, RooufUnNabi, e Mehtab Alam. "Gravity dams under blast loading: A Review". Proceedings of the 12th Structural Engineering Convention, SEC 2022: Themes 1-2 1, n. 1 (19 dicembre 2022): 1273–81. http://dx.doi.org/10.38208/acp.v1.651.
Testo completoAbstract (sommario):
Hi-tech wars, accidental explosions, and subversive bombing attacks have alarmingly increased throughout the globe in recent times. Destructive Beirut explosion that occurred recently is the witness of this fact. Thus, it is increasingly realized that blast loading is a potential threat to the structures of higher importance. With the rapid development of precision and transmission techniques, the accuracy to blast the target and destruction potential of guided or controlled blasts have increased the vulnerability of important structures from subversive attacks in strategic border areas. Consequently, important infrastructure has become susceptible to such harsh blast loadings. Notwithstanding this prevailing belief that risk to water facilities from blast loading is small, yet dam operators and engineers are aware of 9/11 kind of threat [6]. The failure of dams with large reservoirs as a result of blast loads will cause serious economic loss by damaging the structure, hit agricultural sector of the area and also inundate downstream populated area. Modern dams are designed considering conventional loads, including hydrostatic pressure, gravity, sediment pressure, uplift pressure and seismic loads. Seismic performance evaluation of dam-reservoir-foundation systems under strong earthquakes has been widely studied [1, 10, 17, 18, 28, 29]. The effects of explosions on dams are not very well understood because not many investigations have been done on blast performance of dams. This is why most dam engineers lack the understanding of response of dams under blast loading. This review presents the studies conducted on gravity dams subjected to various kinds of impulsive loadings. Also, numerical investigations done on concrete gravity dams (CGD) subjected to blast loading have been comprehensively reviewed. Probable research gap on underwater explosive loading to dams is also presented.
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Sawaguchi, Takahiro, Takehiko Kikuchi, Kazuyuki Ogawa, Fu Xing Yin, Setsuo Kajiwara, Atsumichi Kushibe e Takatoshi Ogawa. "Internal Friction of Fe-Mn-Si-Based Shape Memory Alloys Containing Nb and C and Their Application as a Seismic Damping Material". Key Engineering Materials 319 (settembre 2006): 53–58. http://dx.doi.org/10.4028/www.scientific.net/kem.319.53.
Testo completoAbstract (sommario):
The damping behavior of an Fe-28Mn-6Si-5Cr-0.5NbC (mass%) shape memory alloy was measured by low cycle fatigue tests during tension-compression loadings. A remarkable damping capacity was observed above the strain amplitude of 0.1%, and the specific damping capacity (SDC) parameter reached saturation at ~ 80% above 0.4%. The reversible motion of the γ/ε interfaces is considered to dominate the cyclic deformation behavior, while the work hardening during tension-compression loading is negligible. These characteristics are favorable for seismic damping devices that protect civil structures from earthquakes.
43
Vieux-Champagne, F., Y. Sieffert, S. Grange, C. Belinga Nko'ol, E. Bertrand, J. C. Duccini, C. Faye e L. Daudeville. "Experimental Analysis of a Shake Table Test of Timber-Framed Structures with Stone and Earth Infill". Earthquake Spectra 33, n. 3 (agosto 2017): 1075–100. http://dx.doi.org/10.1193/010516eqs002m.
Testo completoAbstract (sommario):
The seismic performance of timber-framed structures filled with stones and earth mortar has been analyzed by introducing the structural subscales (cell, wall, house) at which monotonic and cyclic loadings were considered. This article aims to present the dynamic behavior of a house as determined through shaking table tests. Based on this experimental multiscale analysis, this paper confirms that timbered masonry structures offer effective seismic resistance; moreover, such a comprehensive analysis helps enhance understanding of the seismic-resistant behavior of timber-framed structures with infill. This paper also aids ongoing development of a numerical tool intended to predict the seismic-resistant behavior of this type of structure.
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Ismail, Rozaina. "Seismic Behaviour of Beris Dam Under Six Earthquake Excitations by using Finite Element Method". journal of Mechanical Engineering 20, n. 2 (15 aprile 2023): 21–35. http://dx.doi.org/10.24191/jmeche.v20i2.22051.
Testo completoAbstract (sommario):
This paper focused on the behavior of the dam when exposed to seismic loading and ability of the dam to withstand the applied loads from various seismic events. The chosen concrete dam to be referred to in the two- dimensional analysis is Beris Dam located in Kedah, Malaysia. A nonlinear dynamic analysis is chosen to analyse the behavior of Beris Dam under selected ground motion. Analysis of the dam is performed using the finite element method by utilizing ABAQUS software. From the cracking analysis pattern, a crack appeared at the upstream face of the dam caused mainly by the excessive tensile stress. Based on the results, the displacement of the dam is increased with the increasing of ground motion data where the displacement occurred in the horizontal direction. The maximum stresses exerted by the dam structure do not exceed the allowable capacity of concrete dams. The stress behaviour of the dam was satisfactorily acceptable as the maximum normal stress and shear stress of the dam when numerous seismic loadings are applied do not exceed the allowable stress capacity which is 800 kN/m2.
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Alati, Natale, Giuseppe Failla e Felice Arena. "Seismic analysis of offshore wind turbines on bottom-fixed support structures". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 373, n. 2035 (28 febbraio 2015): 20140086. http://dx.doi.org/10.1098/rsta.2014.0086.
Testo completoAbstract (sommario):
This study investigates the seismic response of a horizontal axis wind turbine on two bottom-fixed support structures for transitional water depths (30–60 m), a tripod and a jacket, both resting on pile foundations. Fully coupled, nonlinear time-domain simulations on full system models are carried out under combined wind–wave–earthquake loadings, for different load cases, considering fixed and flexible foundation models. It is shown that earthquake loading may cause a significant increase of stress resultant demands, even for moderate peak ground accelerations, and that fully coupled nonlinear time-domain simulations on full system models are essential to capture relevant information on the moment demand in the rotor blades, which cannot be predicted by analyses on simplified models allowed by existing standards. A comparison with some typical design load cases substantiates the need for an accurate seismic assessment in sites at risk from earthquakes.
46
Tung, Albert T. Y., e Anne S. Kiremidjian. "Application of System Reliability Theory in the Seismic Analysis of Structures". Earthquake Spectra 8, n. 3 (agosto 1992): 471–94. http://dx.doi.org/10.1193/1.1585691.
Testo completoAbstract (sommario):
This paper presents a system reliability based analysis method for evaluating the seismic safety/reliability of structures. The seismic analysis procedure developed represents a practical approach in quantifying the risk of structural failure due to seismic hazard. The procedure developed is for framed structures consisting of discrete-state elements. The probabilistic modeling of the seismic load utilizes the hazard curve of the region and the dynamic amplification factor spectrum matching the local geologic condition. The loadings in the structural components are obtained based on a quasi-dynamic analysis and the identification and computation of the component and system failure probabilities are implemented in the software package FAILSF. For illustrative purposes, an elevated liquid storage vessel was used for the application of the seismic analysis procedure.
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Kim, Min Sook, e Young Hak Lee. "Seismic Performance of Reinforced Concrete Columns Retrofitted with Hybrid Concrete Jackets Subjected to Combined Loadings". Materials 15, n. 18 (7 settembre 2022): 6213. http://dx.doi.org/10.3390/ma15186213.
Testo completoAbstract (sommario):
In the existing reinforced concrete columns where they are insufficient seismic details, critical failure mode such as shear failure can be observed under seismic loads. One strategy for the retrofitting of existing concrete columns is to use concrete jacketing. Concrete jacketing consists of a new concrete layer with longitudinal and transverse reinforcements, and can improve seismic resistance capacity. In this paper, a detail of concrete jacket that can be expected for easy construction and improved adhesion performance of longitudinal and transverse reinforcement was proposed. Additionally, a combined cyclic loading test was conducted to consider the seismic load with multiaxial characteristics. The concrete jacket details utilize three components: Steel Grid Reinforcement (SGR), Steel Wire Mesh (SWM), and Steel Fiber Non-Shrinkage Mortar (SFNM). One RC column with non-seismic details and two jacketed RC columns were fabricated to demonstrate the construction efficiencies and structural capacities of the jacketed columns. Two details of jacketed section were considered as variables. It was observed that the specimens retrofitted with concrete jacket resisted torsional load more than the un-retrofitted specimen in terms of crack and failure mode. The experimental results showed that the maximum load of retrofitted specimens was increased by more than 8 times compared to the un-retrofitted specimen, regardless of the jacket details. Newly designed concrete jacket effectively increased the strength. Compared with the un-retrofitted column, the columns retrofitted with the proposed details achieved significant increase in initial stiffness and energy dissipation.
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Mostofizadeh, Sayedali, e Kong Fah Tee. "Static and Seismic Responses of Eco-Friendly Buried Concrete Pipes with Various Dosages of Fly Ash". Applied Sciences 11, n. 24 (9 dicembre 2021): 11700. http://dx.doi.org/10.3390/app112411700.
Testo completoAbstract (sommario):
In this paper, an evaluation based on the detailed failure has been conducted for underground sewage Geopolymer concrete (GPC) pipes under static and seismic loadings with consideration of the optimal time steps in the time-dependent process related to nonlinear behavior of GPC pipes in static and dynamic analyses. The ANSYS platform is employed for improving an advanced FE model for a GPC pipe which can simulate the performance of underground GPC pipes containing various percentages of fly ash (FA) as a Portland cement (PC) replacement. Subsequently, the time-dependent model is used to assess the efficacy of this concrete admixture (FA) in the structural response of the unreinforced GPC pipe in FEM. Indeed, the generated GPC pipe with the three-dimensional model has the potential to capture the nonlinear behavior of concrete which depicts the patterns of tensile cracking and compressive crushing that occur over the applied static loads in the FE model. The main issue in this paper is the assessment of the GPC pipe response typically based on the displacement due to static and seismic loadings. The numerical results demonstrated that the optimal displacement was obtained when the structural response had typically the lowest value for GPC pipes containing 10–30% FA and 20% FA under static and seismic loadings, respectively. Indeed, a reduction by 25% for the vertical displacement of a GPC pipe containing 20% FA was observed compared to that without FA under time-history analysis.
49
Fenwick, R. C., e B. J. Davidson. "Comparative analyses of a multi-storey frame and wall using the current and draft loadings codes". Bulletin of the New Zealand Society for Earthquake Engineering 22, n. 4 (31 dicembre 1989): 181–92. http://dx.doi.org/10.5459/bnzsee.22.4.181-192.
Testo completoAbstract (sommario):
The two draft loadings codes, DZ 4203-86 and 89, introduced major changes in both the response spectra used for seismic design and the methods of analysis. In this paper a wall and a frame, which have been proportioned to provide the seismic lateral load resistance for a 24 storey structure, are analysed by the methods given in these codes to highlight the differences. To simplify the comparison torsional effects have been omitted. The technique of finding a set of lateral loads, by taking the differences of the combined modal storey shears and using these to find the design structural actions, is shown to be inappropriate for structures analysed for the response spectra given in the draft loadings code (DZ 4203, 86 or 89), if the second or higher modes make a significant contribution to the combined modal storey shears.
50
Aleshin, Vladimir, e Vadim Seleznev. "Numerical Structural Analysis of NPP Reinforced Concrete Structures Under Seismic Loading / Numeryczna Analiza Strukturalna Żelbetowych Konstrukcji Elektrowni Jądrowych W Warunkach Obciążeń Sejsmicznych". Journal of KONBiN 23, n. 1 (1 settembre 2012): 29–44. http://dx.doi.org/10.2478/jok-2013-0036.
Testo completoAbstract (sommario):
Abstract The paper describes an approach to the numerical analysis of response of nuclear power plant buildings including soil-structure interaction effects. A reinforced concrete structure of an NPP reactor building under operating and seismic loadings is considered. The simulated seismic load corresponds to a maximum designed earthquake of magnitude 7 (the peak ground surface acceleration is 0.12 g). The numerical analysis was performed by the finite element method in a 3D nonlinear statement using the FEM-programs ANSYS and LS-DYNA. Review of the numerical analysis results demonstrated that the presented technique can be successfully applied to seismic design of NPP structures.