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1
El-Amoury, Tarek Abbas Ghobarah Ahmed. "Seismic rehabilitation of concrete frame beam-column joints /." *McMaster only, 2004.
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Parker, Daniel Edward. "Shear strength within reinforced concrete beam-column joints." Thesis, University of Bolton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492666.
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Reinforced concrete is an economical construction material and is widely used throughout the world in buildings and bridges. The shear strength within beam-column joints in reinforced concrete structures has been identified as an area where further research is still needed in order to form reliable design methods. The aim of this research programme has been to develop a rational analytical model which can be used conveniently in the design of beam-column joints. The work consists of a brief literature review, an extensive experimental programme and the development of a new analytical model for predicting the strength of beam-column joints. The new analytical model is a development of the strut-and-tie model and is believed to be original in two ways: (a) The influence of the shear span and the spacing of the links (if any) are considered directly. (b) The inclination of the compression field is determined by maximising the contribution of the concrete to the stiffness of the member in shear. The new analytical model is shown to predict the strength of the test specimens and of many specimens reported in the literature more reliably than current design codes and standards
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Hannah, Mark Alexander. "Investigation of the design recommendations of reinforced concrete beam-column joints." Thesis, University of Canterbury. Civil Engineering, 2013. http://hdl.handle.net/10092/10981.
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A parametric analysis on 58 beam-column joint specimens has been conducted. The analysis considered 14 fundamental parameters in the design of each specimen and two performance indicators: the horizontal shear strength ratio between the maximum measured strength and the theoretical strength at beam yield, and the nominal curvature ductility of the adjacent beams. Each parameter was varied by a power function, while the linear correlation coefficient between each parameter and performance indicator was recorded. A combined multiple parameter analysis was then conducted to show the interaction of the design parameters and show the representative influences of each parameter based on the magnitude of the applied power functions.
Two design equations were constructed from the most influential design parameters, one for each performance indicator. The shear strength ratio was found to be governed by the horizontal joint shear stress, the column axial stress and the yield strength of the longitudinal beam reinforcement. The available curvature ductility of the adjacent beams was also found to be governed by the horizontal joint shear stress, the column axial stress and the yield strength of the longitudinal beam reinforcement, but also the quantity of the horizontal joint shear reinforcement.
The influence of the column axial stress on both performance indicators was found to be best represented by a quadratic function. This was because the column axial stress was found to be beneficial up to stress levels of , but axial stress levels exceeding were found to be detrimental to the performance of the beam-column joint, compared to a joint with no axial stress on the columns. The non-linear relationship of the column axial stress agreed with the design assumptions in NZS 3101 for low axial stress values, but at higher axial stress values NZS 3101 assumes a continued performance increase as a result of increasing axial stress, which has been found to be un-conservative. Additionally, an interaction between the column axial stress and the horizontal joint shear stress has been identified. As a result, beam-column joints with high column axial stress levels above 0.40 and horizontal joint shear stress levels in the order of have been shown to fail in a brittle crushing of the concrete in the joint core. Considering this behaviour, it is recommended that the column axial stress levels in earthquake designed beam-column joints should not exceed 0.35 .
The results of the parametric analysis were then compared against the current NZS 3101 design equations for conservatism. It was found that a reduction in the horizontal joint shear reinforcement may be possible for beam-column joints incorporating Grade 300 steel in the longitudinal reinforcement of the beams and axial stress levels below 0.25 , but when Grade 500 steel is used or the column axial stress is greater than 0.25 , an increase in the joint shear reinforcement is required compared to NZS 3101. The current NZS 3101 design requirement of at least 40% of the joint shear force, to be resisted by means of joint shear reinforcement, has been found to be appropriate.
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Salisbury, Seth T. "Repair and strengthening of reinforced concrete beam-column joints." Connect to resource, 2010. http://hdl.handle.net/1811/45377.
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Vollum, Robert Lars. "Design and analysis of reinforced concrete beam-column joints." Thesis, Imperial College London, 1998. http://hdl.handle.net/10044/1/7500.
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Jemaa, Yaser. "Seismic behaviour of deficient exterior RC beam-column joints." Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/15025/.
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Post-earthquake reconnaissance and results of previously conducted experiments show that stiffness and strength deterioration of beam-column joints can have a detrimental effect on the integrity and vulnerability of reinforced concrete frame structures, especially in older buildings in developing countries. As a result, there is a need to develop efficient structural evaluation techniques that are capable of accurately estimating the strength and deformability of existing buildings to facilitate the development of safer, simpler, and lower cost retrofit solutions and thus contributing to risk mitigation. The current research is part of a general effort that is being carried out at the University of Sheffield to quantify and develop strategies for the mitigation of seismic risk in developing countries. The primary aim of this work is to improve the current understanding of the seismic behaviour of deficient exterior reinforce concrete beam-column joints. Seven full-scale isolated exterior beam-column joints were tested under quasi-static cyclic loading to investigate and quantify the effects of using different types of beam reinforcement anchorages and low column axial loads on the seismic shear performance of exterior beam-column joints with no shear reinforcement. Contrary to what is reported in the literature, the test results show that increasing the column axial load even at very low levels «O.2f'oAg,) can enhance the joint shear strength of deficient exterior joints (exhibiting pure shear failure) by up to 15%. The test results also show that, for the same joint panel geometry and column axial load, the type of beam anchorage detail, whether it is a straight bar, long or short hook, can influence the joint shear strength by up to 34%. A new analytical model that predicts the shear strength of deficient exterior beam-column joints in both loading directions and takes into account the column axial load and bond conditions within the joint is developed. The model predicts with good accuracy the strength of the tested specimens in addition to other specimens reported by other researchers. Furthermore, a springbased exterior beam-column joint model for finite element analysis of deficient RC frames is proposed. The model development includes a joint shear stress-strain constitutive model based on the developed strength model. The simulated response using the proposed model shows good agreement with the experimentally observed response.
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Motamed, Jubin. "Monolithic beam to external column joints in reinforced concrete." Thesis, University of Westminster, 2010. https://westminsterresearch.westminster.ac.uk/item/90727/monolithic-beam-to-external-column-joints-in-reinforced-concrete.
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The benefits of high strength concrete (HSC) in the construction of multi-storey buildings are commonly acknowledged. Past researchers have investigated the suitability of design codes for the use of HSC [1]. However, there are concerns about the shear behaviour of HSC beams and BCJ used in the construction of these buildings. HSC beams have equal or less shear resistance compared to normal strength concrete (NSC) beams [2], and the brittleness of HSC material could be unsuitable for BCJ as confinement stirrups may not be as effective as NSC in the column due to a smaller Poisson’s ratio. This research investigates the behaviour of HSC beams, BCJ and transfer beam column joints (TBCJ), and develop appropriate design modifications to improve their shear capacity. HSC beams were strengthened with horizontal web bars (HWB), while TBCJ were strengthened with central vertical bars (CVB). Finite element (FE) models were developed for these structures and the numerical results were compared with those of the published experimental results, concluding that good agreement had been achieved. Beam span/depth (a/d) ratio of 1.5≤a/d ≤3.02 and BCJ of beam to column depth ( db/dc ) ratio of 1.33 ≤ db/dc ≤3.1 were analysed. The FE models were compared with published test results and further ones were developed to carry out various parametric investigations. Struts and ties were mechanically modelled for beams with HWB and for TBCJ with CVB are used to recommend design equation modifications for the design of HSC beams with HWB and TBCJ with CVB. It was found that HWB and CVB are effective in beams and BCJ only with HSC as they have little influence when they were used with NSC. Using HWB in HSC beams and CVB in HSC TBCJ improved the shear capacity of these structures by 130% and 31% respectively. 1 - Regan, P. E., Kennedy -Reid I. L., Pullen, A. D., Smith, D. A. ‘The influence of aggregate type on the shear resistance of reinforced concrete’ – The Structural Engineer. 6 December 2005. p 27-32. 2 - Al-Hussaini, A. Motamed, J. ‘HSC beams with combination of links and horizontal web steel as alternative shear reinforcement’. 6th International Symposium on Utilization of High Strength/High Performance Concrete, Leipzig, June 2002. p 611- 619
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Leong, Mun-Foo. "MOMENT-ROTATION CHARACTERISTICS OF BEAM-TO-COLUMN CONNECTIONS." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275028.
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MEIRA, MAGNUS THIAGO DA ROCHA. "EXPERIMENTAL STUDY OF BEAM-COLUMN JOINTS WITH DIFFERENT CONCRETE STRENGTHS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2009. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=15357@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
O emprego de concretos de diferentes resistências em pilares e nos demais elementos do edifício, sendo o concreto dos pilares o de maior resistência, tem sido uma opção adotada em algumas edificações. Nas construções em geral, o concreto do pavimento é colocado continuamente atravessando o nó pilar-pavimento. Como resultado, o concreto da parte do pilar na região de encontro entre o pavimento e o pilar tem uma resistência menor do que no resto do pilar. Como, em geral, esta região do pilar se encontra confinada pelo pavimento, surge então a dúvida sobre qual é a resistência à compressão que se deve utilizar no cálculo do pilar; se deve ser a do pilar, a do pavimento ou um valor intermediário. O objetivo do trabalho é estudar experimentalmente a influência do confinamento do nó em pilares interceptados por vigas. As variáveis adotadas foram a taxa de armadura e a deformação específica inicial na armadura longitudinal das vigas. Nesta tese foram estudados experimentalmente quatro espécimes com vigas nas duas direções e oito espécimes com vigas em uma direção. Também foram ensaiados dois pilares isolados e homogêneos, um com concreto de mesma resistência à compressão do concreto utilizado no pilar e outro com concreto com resistência igual à resistência do concreto das vigas. As resistências nominais dos concretos das vigas e dos pilares foram 30 MPa e 70 MPa respectivamente. Os resultados indicaram que o confinamento promovido por vigas nas duas direções resulta num aumento significativo na carga de ruptura. O aumento da taxa de armadura das vigas aumenta a capacidade final somente nos espécimes com vigas nas duas direções. A influência da deformação inicial na armadura das vigas é inexpressiva.
The use of concretes with different strengths in columns and in the others elements of the floor, with the columns having the concrete with the highest strength, has been an option adopted in some buildings. In general, the concrete of the floor is poured continuously crossing the floor-column joint. As a result, the concrete strength in the joint region is lower than the concrete strength of the rest of the column. Since, in general, the joint region is confined by the floor, a doubt on the effective strength of the joint remains. The objective of the present work was to study experimentally the influence of the lateral confinement in the joint region of columns intercepted by beams. The variables were the reinforcement ratio and the initial strain in the tension reinforcement of the beams. In the present thesis, four specimens with beams in one direction and eight specimens with beams in two directions were studied experimentally. In addition, two isolated columns were also tested, one with concrete of same strength of the concrete of the columns and other with concrete of same strength of the concrete of the beams. The compressive concrete strength of the beams and columns were 30 MPa and 70 MPa respectively. The results indicated that the confinement provided by beams in two directions causes a significant increase of the failure load. The increase of the tension reinforcement ratio of the beams increases the failure load only in specimens with beams in two directions. The initial strain in the tension reinforcement of the beams has no effect on the ultimate capacity of the specimens.
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Elflah, Mohamed A. Hussaen. "Structural behaviour of stainless steel bolted beam to column joints." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8545/.
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Initially, two experimental programmes studying the structural behaviour of stainless steel beam-to-open column joints and beam-to-tubular column joints under static loads are reported in detail. The joint configurations tested include flush and extended end plate connections, top and seat cleat connections and top, seat and web cleat connections. The full moment-rotation characteristics are reported in detail. It is observed that the connections displayed excellent ductility, superior than that of equivalent carbon steel connections, and attained loads much higher than the ones predicted by design standards for carbon steel joints. Nonlinear FE models have been developed and validated against the experimental results. The FE models are shown to accurately replicate the experimentally determined, initial stiffness, ultimate resistance, overall moment-rotation response and observed failure modes. In addition, a comprehensive parametric study is conducted. The design rules for stainless steel connections, which are based on the specifications of EN 1993-1-8 for carbon steel joints, are reviewed and are found to be overly conservative in terms of strength and inaccurate in terms of stiffness thus necessitating the development of novel design guidance in line with the observed structural response. Hence, simplified mechanical models in line with the observed response are developed.
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Fisher, Matthew John. "Experimental Evaluation of Reinforcement Methods for Concrete Beam-Column Joints." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1243628129.
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Smallidge, Jeffrey M. "Behavior of bolted beam-to-column T-stub connections under cyclic loading." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/19534.
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Cheung, (Patrick) Pak Chiu. "Seismic design of reinforced concrete beam-column joints with floor slab." Thesis, University of Canterbury. Civil Engineering, 1991. http://hdl.handle.net/10092/9451.
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Beam-column joints are addressed in the context of current design procedures and performance criteria for reinforced concrete ductile frames subjected to large earthquake motions. Attention is drawn to the significant differences between the pertinent requirements of concrete design codes of New Zealand and the United States for such joints. The difference between codes stimulated researchers and structural engineers of the United States, New Zealand, Japan and China to undertake an international collaborative research project. The major investigators of the project selected issues and set guidelines for co-ordinated testing of joint specimens designed according to the codes of the countries. The tests conducted at the University of Canterbury, New Zealand, are reported. Three full-scale beam-column-slab joint assemblies were designed according to existing code requirements of NZS 3101:1982, representing an interior joint of a one-way frame, an interior joint of a two-way frame, and an exterior joint of a two-way frame. Quasistatic cyclic loading simulating severe earthquake actions was applied. The overall performance of each test assembly was found to be satisfactory in terms of stiffness, strength and ductility. The joint and column remained essentially undamaged while plastic hinges formed in the beams. The weak beam-strong column behaviour sought in the design, desirable in tall ductile frames designed for earthquake resistance, was therefore achieved. Using the laws of statics and test observations, the action and flow of forces from the slabs, beams and column to the joint cores are explored. The effects of bond performance and the seismic shear resistance of the joints, based on some postulated mechanisms, are examined. Implications of the test results on code specifications are discussed and design recomendations are made.
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Ridwan. "Reinforced concrete beam-column joints strengthened in shear with embedded bars." Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/7138/.
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Beam-column (BC) joints play an important role in the seismic performance of moment-resisting reinforced concrete (RC) frame structures. Without adequate joint shear reinforcement, BC joints can be the most vulnerable elements during an earthquake. Several techniques for improving the seismic performance of BC joints have been proposed, but they have been criticised for being labour-intensive and/or susceptible to premature debonding. This research explores the application of the deep embedment technique for strengthening a shear-deficient beam-column joint. Two approaches, experimental and finite element (FE) study were conducted. The experiment contained the tests of seven exterior RC BC joints under constant column axial load and a reverse cyclic load at the beam end. Variables considered during the experiments were the material type and embedded reinforcement ratio. The FE study included the modelling of the tested specimens using ABAQUS and parametric study to asses the effect of column axial load, concrete compressive strength and embedded bar size on joint shear strength. The experimental results showed the strengthened specimens had superior global and local behaviour compared to the control one. In addition, the maximum joint shear strength also changes linearly with the variation of the concrete strength, column axial load and embedded bar size.
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Rifai, Abdussalam Mahmud. "Behaviour of columns in sub-frames with semi-rigid joints." Thesis, University of Sheffield, 1987. http://etheses.whiterose.ac.uk/3050/.
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The behaviour of limited subassemblages with flexible beans and semi-rigid beam to column connections was studied using a computer program in which the finite element method was employed in a non-linear analysis which accounts for the presence of semi-rigid connections and the inelastic behaviour of frames. The program accounts for many other factors such as initial imperfections and residual stresses. The theoretical background to the present computer program has been presented along with the program layout. The program was used to simulate some of the experimental results obtained from tests on rigidly and flexibly connected frames with different combinations of beam and column loads. The analytical results were found to compare reasonably well with the experimental results. The program was also used to simulate a series of I-shaped subassemblages that were tested at the University of Sheffield. Comparisons were made between the analytical and experimental results characterized by the maximum loads, load-deflection curves and load- moment curves. Good agreement was obtained between the analytical and the experimental load-deflection curves for all of the cases considered. The general trends of the measured and calculated load- moment curves for most cases were found to be comparable. The recommendations given in B35950 for the design of columns in simple construction were applied to all cases in the last series and were found unconservative in the cases of balanced loading and conservative in the cases of unbalanced loads. A limited parametric study was conducted to study the effects of semi-rigid joints, bean flexibility and type of loading. In this study, an I-shaped subassemblage was analysed for different load types and different types of beam to column connections. A substantial effect was recognized due to the presence of semi-rigid connections whether or not a beam load was applied. Beam flexibility was also seen to affect the carrying capacity of the subassemblage under the action of column load only although this effect was less noticeable than that of the connection flexibility. The presence of beam load was found to result in an unexpected interaction curve which relates the total force in the column to the moment that is transmitted to the column's end. An almost linear relationship with negative gradient seems to exist between the column and beam loads. It is pointed out that all the findings of the present study are based on the range of cases considered in the parametric study but it is suggested that they serve as indicators to the behaviour of any the subassemblage under axial load oniy or axial load combined with beam loads. A few recommendations for future work are presented.
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Byrne, Joseph D. R. "Bond and shear mechanics within reinforced concrete beam-column joints incorporating the slotted beam detail." Thesis, University of Canterbury. Civil & Natural Resources Engineering, 2012. http://hdl.handle.net/10092/8716.
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The recent earthquakes in Christchurch have made it clear that issues exist with current RC frame design in New Zealand. In particular, beam elongation in RC frame buildings was widespread and resulted in numerous buildings being rendered irreparable. Design solutions to overcome this problem are clearly needed, and the slotted beam is one such solution. This system has a distinct advantage over other damage avoidance design systems in that it can be constructed using current industry techniques and conventional reinforcing steel. As the name suggests, the slotted beam incorporates a vertical slot along part of the beam depth at the beam-column interface. Geometric beam elongation is accommodated via opening and closing of these slots during seismically induced rotations, while the top concrete hinge is heavily reinforced to prevent material inelastic elongation.
Past research on slotted beams has shown that the bond demand on the bottom longitudinal reinforcement is increased compared with equivalent monolithic systems. Satisfying this increased bond demand through conventional means may yield impractical and economically less viable column dimensions. The same research also indicated that the joint shear mechanism was different to that observed within monolithic joints and that additional horizontal reinforcement was required as a result.
Through a combination of theoretical investigation, forensic analysis, and database study, this research addresses the above issues and develops design guidelines. The use of supplementary vertical joint stirrups was investigated as a means of improving bond performance without the need for non-standard reinforcing steel or other hardware. These design guidelines were then validated experimentally with the testing of two 80% scale beam-column sub-assemblies. The revised provisions for bond within the bottom longitudinal reinforcement were found to be adequate while the top longitudinal reinforcement remained nominally elastic throughout both tests. An alternate mechanism was found to govern joint shear behaviour, removing the need for additional horizontal joint reinforcement. Current NZS3101:2006 joint shear reinforcement provisions were found to be more than adequate given the typically larger column depths required rendering the strut mechanism more effective.
The test results were then used to further refine design recommendations for practicing engineers. Finally, conclusions and future research requirements were outlined.
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Jiménez, Torres Adrià. "Seismic design of steel beam-to-column joints with reduced beam section using European hotrolled." Doctoral thesis, Universitat Politècnica de Catalunya, 2021. http://hdl.handle.net/10803/673353.
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The design rules on Reduced Beam Sections (RBS) are covered in the Eurocodes in EN1998-3 as a possible solution to improve rotation capacity of beams for the retrofit of existing structures. The design rules are very similar to those in AISC358
provisions, although European cross-sections and steel grades are different. Research pieces on RBS in a European environment are few and do not study this matter with an extensive parametric study to assess their behaviour. Moreover, the
design rules in EN1998-3 only show how to design the weakened section of the beam, but they do not provide any additional information on whether further action is needed on the structure for the design of other members such as braces or if special considerations need to be made for connection detailing. The current state of the Eurocodes does not consider the design of
a new structure with RBS, while AISC358 provisions do allow for new RBS designs.
The aim of this PhD thesis is to study the behaviour of the RBS and find the most relevant design parameters affecting its response in a beam-to-column assembly level and to study the benefits of incorporating RBS as a solution for the design of
new structures in seismic areas. In order to fulfill the first goal, a numerical model has been developed in Abaqus in order to assess the behaviour of RBS and to discuss the results obtained from them. Hot-rolled European sections have been studied from the HEA and IPE cross-section families, as well as a built-up slender girder and an American Jumbo section.
Several different cutouts (or trimmed flange widths) are investigated, as well as S235 and S355 steel grades with their cyclic hardening properties. The influence on the column web panel strength is also considered in the parametric study. The
results obtained are then examined to compare degradation ratios, overstrength ratios, lateral-torsional buckling development, dissipated plastic work and plastic damage by means of equivalent plastic strains (PEEQ).
In order to fulfill the second goal, two different studies have been performed to assess the influence of the RBS in a structure subjected to seismic load. The behaviour of a structure provided with RBS is compared to that of a control structure without RBS. The results have been obtained and the differences found have been quantified in order to objectively report the benefits found when adopting RBS
After having studied the behaviour of the RBS both locally (at a beam-to-column level) and globally, the main conclusions have been derived. Also, design recommendations to take into consideration for the design of new RBS are provided in order
to ensure a proper behaviour of the RBS when subjected to seismic loads and to guarantee overall good structural behaviour.Les regles de disseny de les bigues de secció reduïda (RBS) es cobreixen als eurocodis en la norma EN1998-3 com a possible solució per millorar la capacitat de rotació de bigues per a la rehabilitació de les estructures existents. Les normes de disseny són molt similars a les de les disposicions de l'AISC358, tot i que les seccions transversals europees i els graus d'acer són diferents. Les investigacions sobre RBS en un entorn europeu són poques i no estudien aquest tema amb un ampli estudi paramètric per avaluar el seu comportament. A més, les regles de disseny de la norma EN1998-3 només mostren com dissenyar la secció reduïda de la biga, però no proporcionen informació addicional sobre si cal fer més accions a l'estructura per al disseny d'altres elements o si calen altres consideracions especials en el detallat de la connexió. L'estat actual dels eurocodis no contempla el disseny d'una nova estructura amb RBS, mentre que les disposicions AISC358 permeten nous dissenys de RBS. L'objectiu d'aquesta tesi doctoral és estudiar el comportament de les RBS i trobar els paràmetres de disseny més rellevants que afecten la seva resposta a nivell local de biga a columna i estudiar els avantatges d'incorporar RBS com a solució per al disseny de noves estructures en zones sísmiques. Per complir el primer objectiu, s'ha desenvolupat un model numèric amb Abaqus per avaluar el comportament de RBS i discutir els resultats obtinguts d'ells. S'han estudiat seccions europees laminades en calent pertanyents a les famílies de seccions transversals HEA i IPE, així com una biga esvelta armada i una secció Jumbo americana. S'investiguen divers os retalls (o amplades d'ales de biga retallades), així com els graus d’acer S235 i S355 amb les seves propietats d'enduriment cíclic. La influència de la resistència relativa de la zona de l'anima de la columna també es considera en l’estudi paramètric. A continuació, s'examinen els resultats obtinguts per comparar les ràtios de degradació, les ratios de sobrerresistència, el desenvolupament de vinclament lateral-torsional, l'energia dissipada per deformació plàstica i el dany plàstic mitjançant deformacions plàstiques equivalents (PEEQ). Per tal de complir el segon objectiu, s'han dut a terme dos estudis diferents per avaluar la influència de la RBS en una estructura sotmesa a càrrega sísmica. El comportament d'una estructura proveïda de RBS es compara amb el d'una estructura de control sense RBS. S'han obtingut els resultats i s'han quantificat les diferències trobades per tal d'informar objectivament dels beneficis trobats en adoptar RBS. Després d'haver estudiat el comportament de la RBS tant a nivell local (a nivell de biga a columna) com a nivell global, s'han extret les principals conclusions. A més, es proporcionen recomanacions de disseny a tenir en compte per al disseny de nous RBS per tal de garantir un comportament correcte de l'RBS quan està sotmès a càrregues sísmiques i per garantir un bon comportament estructural en general.
Enginyeria de la construcció
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Birss, B. R. "The elastic behaviour of earthquake resistant reinforced concrete interior beam-column joints." Thesis, University of Canterbury. Civil Engineering, 2013. http://hdl.handle.net/10092/7750.
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This report is concerned with the theoretical and experimental study of the behaviour of interior reinforced concrete beam-column joints under simulated earthquake loading.
An experimental program investigated the performance of two beam-column joint subassemblages subjected to static cyclic loading within elastic limits. The post-elastic behaviour of the two test units was then examined by testing to failure.
A theoretical method for analysis of the joint shear resisting mechanisms is reviewed and analyses of prototype beam-column joints are reported. Results of this analysis were then compared with those obtained from the test units. The design method is shown to provide a satisfactory and conservative estimate of the joint shear reinforcement required in an elastic beam-column joint.
The failure of the joints in the test units verified the expectations that their response to inelastic seismic load demands would have been unsatisfactory.
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Thaker, Tariq Ali. "Experimental and nonlinear finite element analysis of double skin beam-column joints." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/16042/.
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The Double Skin Composite (DSC) or Steel-Concrete-Steel (SCS) elements (beams, slabs and columns) have been subjected to intensive studies during the last three decades. Member beam, column and slab have been studied under monotonic, cyclic and fatigue loading, and there are also a few studies on impact loading to assess the structural response of such constructions. Validating connectivity between the DSC beam and DSC columns is behind the usage of such constructional systems since all the present studies focus on individual members. The main objective of this thesis was to introduce the Double Skin Composite (DSC) beam-column joint as a new structural element. Experimental investigation and Nonlinear Finite Element Modelling (FEM) of the structural behaviour of the DSC joint subjected to monotonic and quasi-static loading was introduced. Five DSC joints have been tested to assess the efficiency of the DSC beam-column joint in its basic design and to identify the most efficient strengthening method. Further, six DSC beam-column joints were tested to study the effect of steel fibre (SF) and the effect of high-strength concrete (HSC) on the behaviour of the joint under monotonic loading and under cyclic loading. The general FE Package ABAQUS 6.10 was used to model the nonlinear behaviour of the DSC joint. The Concrete Damage Plasticity Model (CDPM) was used to model the concrete in tension and compression, and the steel elements of the composite were modelled using the elastic-plastic model. The model was validated against the experimental result and showed good agreement in predicting the maximum load and the general behaviour with a deviation of 10% or less. The examined strengthening methods showed improvement in the ultimate load capacity of between 517% and 871%. SFC and HSC provided the best performance in increasing the ultimate load and moving the location of the plastic hinge away from the face of the column. The validated FE model was used to conduct a parametric study to investigate the effect of the concrete compressive strength, shear stud connector spacing to steel plate thickness ratio, and the stud diameter to steel plate thickness ratio. The parametric study findings were in good agreement with experimental observations such as that the concrete compressive strength had a significant effect on the joint shear resistance and ultimate load.
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Pohoryles, D. A. "Realistic FRP seismic strengthening schemes for interior reinforced concrete beam-column joints." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1553180/.
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The observation, in recent earthquakes, of brittle collapses of reinforced concrete (RC) structures built before the introduction of detailed seismic design codes (pre-1970’s), underlines the need for significant upgrades to the existing RC building stock. In particular, weak-column/strong-beam mechanisms and shear failures have potentially catastrophic impacts that could be addressed by repair and retrofit solutions. In recent years, retrofits with fibre reinforced polymers (FRP) are becoming increasingly popular due to the benefits of corrosion resistance, high strength-to-weight ratio and reduced labour time. Experimental evidence for the efficiency of such schemes for joint strengthening can be found in the literature. An analysis of all available literature shows that the reduced scale of most tested specimens, as well as the omission of slabs and transverse beams in many studies, may lead to an unrealistic assessment of FRP retrofit schemes. In this study, pre-1970’s full-scale interior beam-column joints with slab and transverse beams are hence tested under realistic conditions in order to propose and assess new and practical FRP retrofit solutions for seismic actions. Three carbon FRP (CFRP) retrofit schemes with selective retrofit objectives are designed using outcomes from the literature and from calibrated finite-element models. The retrofit schemes are composed of a combination of FRP strengthening and selective weakening components to ensure failure of inadequately reinforced RC beam-column joints according to capacity design principles. The objectives of the schemes include the enhancement in lateral capacity and ductility, as well as changing the failure mechanism of the joint. Results from full-scale cyclic tests on the CFRP retrofitted specimens are compared to the behaviour of a deficient specimen and a specimen designed to modern guidelines (EC8), highlighting the successful achievement of the respective retrofit objectives. To evaluate the effect of the realistic set-up, the results are also compared to specimens without slab and transverse beams, highlighting their importance. Finally, new design equations, to be used in conjunction with existing guidelines, are formulated to ease the practical adoption of the proposed retrofit scheme.
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黃崑 and Kun Huang. "Design and detailing of diagonally reinforced interior beam-column joints for moderate seismicity regions." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B31244233.
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Islam, Mohammad Aminul. "Constitutive modeling and plastic analysis with application to beam-to-column connections." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184486.
Full textAbstract:
Analysis and design of connections, such as beam-to-column connections, pose various complexities such as nonlinear behavior of material and geometric condition, irregularities in geometry and boundary condition. The main purpose of these types of connections is to provide adequate structural strength and a sufficiently stiff structure at working loads, and to possess sufficient ductility and strength at overloads such as may occur during a major earthquake. At present the design profession does not have established guidelines for estimating the ultimate moment and shear capacity of these connections. The assumption of linear elastic material behavior of the connections is no longer valid when the elements are stressed beyond the yield stress of the material. For such problems encountered in the design of typical structures, either the closed-form analytical solutions are extremely complex or cannot be obtained at all. Thus, numerical techniques such as finite difference, finite element and boundary integral methods are used. In this study, a finite element program is developed for plastic analysis of connections such as beam-to-column connection using a constitutive law of the material, a three parameter stress-strain relationship, which gives stress explicitly in terms of strain. One hundred and fifteen cases of beam-to-column connections subjected to moment are analysed with the finite element program developed in this study, and the results are compared with the existing approximate solution by yield line theory to propose a simple formula to correlate actual ultimate capacity to the approximate solution.
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Ocel, Justin M. "Cyclic behavior of steel beam-column connections with shape memory alloy connecting elements." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/19110.
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Bousri, Yahia. "Experimental and analytical study of reinforced concrete external beam-column subjected to cyclic loading." Thesis, University of Bristol, 1994. http://hdl.handle.net/1983/692583ab-1cce-4e31-9250-b1c322c8caef.
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Lau, Shuk-lei. "Rehabilitation of reinforced concrete beam-column joints using glass fibre reinforced polymer sheets." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B32001630.
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Brooke, Nicholas J. "Improving the performance of reinforced concrete beam-column joints designed for seismic resistance." Thesis, University of Auckland, 2011. http://hdl.handle.net/2292/8697.
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The testing of thirteen large scale beam-column joints forms the framework for the content of this thesis. The thirteen tests were divided into three series, each of which investigated an aspect of earthquake resistant design of moment resisting frames. The results obtained from testing the first series of four beam-column joints contradicted the conclusion of earlier research that design criterion specifying the ratio of column depth to bar diameter required to anchor beam longitudinal reinforcement at interior beam-column joints was non-conservative when applied to Grade 500E reinforcement. As a result, a database of approximately 100 beam-column joints was assembled and used to parametrically develop an improved design criterion that was shown to satisfactorily predict experimental performance based on the anchorage length provided. It was also shown in the first part of the thesis that the flexural overstrength factor should be the same irrespective of whether Grade 300E or Grade 500E longitudinal reinforcement is used in a beam. This finding contradicts current New Zealand practice, which specifies a higher flexural overstrength factor for Grade 500E reinforcement. The second set of four tests assessed the performance of beam-column joints constructed using inorganic polymer concrete. The properties of inorganic polymer concrete are similar to those of concrete produced using Portland cement, but the production of inorganic polymer concrete releases 80% less "greenhouse gases" into the atmosphere than the production of Portland cement concrete. The results of these tests showed that satisfactory performance can be expected from beam-column joints designed using existing New Zealand standards but constructed using inorganic polymer concrete. The final series of five tests were conducted to assess the performance of beam-column joints when the joint core was constructed using high performance fibre reinforced cementitious composites (HPFRCC) and contained no conventional transverse reinforcement. The results of this testing showed that satisfactory performance could be achieved when the magnitude of the joint core shear stress was commensurate with the strength of the HPFRCC used. It was also evident that HPFRCC is significantly superior to plain concrete with regards to the anchorage of reinforcement within the joint core. A number of comments were made regarding the practicalities of using HPFRCC joint cores in real structures, from which it was concluded that for most structures HPFRCC joint cores are unlikely to be a practical alternative to conventionally reinforced joint cores.
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Lau, Shuk-lei, and 劉淑妮. "Rehabilitation of reinforced concrete beam-column joints using glass fibre reinforced polymer sheets." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B32001630.
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Reys, De Otiz Iclea. "Strut-and-tie modelling of reinforced concrete : short beams and beam-column joints." Thesis, University of Westminster, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334612.
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Xing, Chenxi. "An Analytical Study on the Behavior of Reinforced Concrete Interior Beam-Column Joints." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/92873.
Full textAbstract:
Reinforced concrete (RC) moment frame structures make up a notable proportion of buildings in earthquake-prone regions in the United States and throughout the world. The beam-column (BC) joints are the most crucial regions in a RC moment frame structure as any deterioration of strength and/or stiffness in these areas can lead to global collapse of the structure. Thus, accurate simulations of the joint behavior are important for assessment of the local and global performance of both one-way and two-way interior BC joints. Such simulations can be used to study the flexural-shear-bond interaction, the failure modes, and sensitivity of various parameters of structural elements. Most of the existing analytical approaches for interior BC joints have either failed to account for the cyclic bond-slip behavior and the triaxial compressive state of confined concrete in the joint correctly or require so many calibrations on parameters as to render them impractical. The core motivation for this study is the need to develop robust models to test current design recommendations for 3D beam-column-slab subassemblies subjected to large drifts. The present study aims to first evaluate the flexural-shear-bond interactive behavior of two-way beam-column-slab interior connections by both finite element and nonlinear truss methodologies. The local performance such as bond-slip and strain history of reinforcing steel are compared with the experimental results for the first time. The reliability of applied finite element approach is evaluated against a series of one-way interior BC joints and a two-way interior beam-column-slab joint. The accuracy and efficiency of the nonlinear truss methodology is also evaluated by the same series of joints. Results show good agreement for finite element method against both global and local response, including hysteretic curve, local bond-slip development and beam longitudinal bar stress/strain distributions. The nonlinear truss model is also capable in obtaining satisfactory global response, especially in capturing large shear cracks. A parametric study is exhibited for a prototype two-way interior beam-column-slab joint described in an example to ACI 352R-02, to quantify several non-consensus topics in
the design of interior BC connections, such as the joint shear force subjected to bidirectional cyclic loading, the development of bond-slip behavior, and the failure modes of two-way interior joints with slab. Results from connections with different levels of joint shear force subjected to unidirectional loading show that meeting the requirements from ACI 352 is essential to maintain the force transfer mechanism and the integrity of the joint. The connections achieved satisfactory performance under unidirectional loading, while the bidirectional monotonic loading decreases the joint shear force calculated by ACI 352 by 10%~26% based on current results. Poorer performance is obtained for wider beams and connections fail by shear in the joint rather than bond-slip behavior when subjected to bidirectional cyclic loading. In general, the study indicates that the ACI352-02 design methodology generally results in satisfactory performance when applied to 2D joints (planar) under monotonic and cyclic loads. Less satisfactory performance was found for cases of 3D joints with slabs.Doctor of Philosophy
Reinforced concrete (RC) moment frames are one of the most popular structure types because of their economical construction and adaptable spaces. Moment frames consist of grid-like assemblages of vertical columns and horizontal beams joined by cruciform connections commonly labelled as beam-column joints. Because of the regularity of the grid and the ability to have long column spacing, moment frames are easy to form and cast and result in wide open bays that can be adapted and readapted to many uses. In RC structures, steel bars embedded in the concrete are used to take tensile forces, as concrete is relatively weak when loaded in tension. Forces are transferred between the steel and concrete components by so-called “bond” forces at the perimeter of the bars. The proper modeling of the behavior of bond forces inside the beam-column joints of reinforced concrete moment frames is the primary objective of this dissertation. Reinforced concrete moment frames constitute a notable proportion of the existing buildings in earthquake-prone regions in the United States and throughout the world. The beam-column joints are the most crucial elements in a RC moment frame structure as any deterioration of strength and/or stiffness in these areas can lead to global collapse of the structure. Physical experimentation is the most reliable means of studying the performance of beam-column joints. However, experimental tests are expensive and time-consuming. This is why computational simulation must always be used as a supplemental tool. Accurate simulations of the behavior of beam-column joints is important for assessment of the local and global behavior of beam-column joints. However, most of the existing analytical approaches for interior beam-column joints have either failed to account for the bond-slip behavior and the triaxial compressive state of confined concrete in the joint correctly or require so many calibration parameters as to render them impractical. The present study aims to provide reliable numerical methods for evaluating the behavior of two-way beam-column-slab interior joints. Two methods are developed. The v first method is a complex finite element model in which the beam-column joint is subdivided into many small 3D parts with the geometrical and material characteristics of each part carefully defined. Since the number of parts may be in the hundreds of thousands and the geometry and material behavior highly non-linear, setting up the problem and its solution of this problem requires large effort on the part of the structural engineer and long computation times in supercomputers. Finite element models of this type are generally accurate and are used to calibrate simpler models. The second method developed herein is a nonlinear truss analogy model. In this case the structure is modelled as nonlinear truss elements, or elements carrying only axial forces. When properly calibrated, this method can produce excellent results especially in capturing large shear cracks. To evaluate the accuracy and to quantify the current seismic design procedure for beam-column joints, a prototype two-way interior beam-column-slab joint described in an example to ACI 352R-02, the current design guide used for these elements in the USA, is analytically studied by the finite element methodology. The study indicates that the ACI352-02 design methodology generally results in satisfactory performance when applied to one-way (planar) joints under monotonic and cyclic loads. Less satisfactory performance was found for cases of three-dimensional (3D) joints with slabs.
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Bowers, Jeremy Thomas. "Nonlinear Cyclic Truss Model for Beam-Column Joints of Non-ductile RC Frames." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/50437.
Full textAbstract:
Reinforced concrete (RC) moment frames comprise a significant portion of the built environment in areas with seismic hazards. The beam-to-column joints of these frames are key components that have a significant impact on the structure's behavior. Modern detailing provides sufficient strength within these joints to transfer the forces between the beams and the columns during a seismic event, but existing structures built with poor detailing are still quite prevalent. Identifying the need and extent of retrofits to ensure public safety through nondestructive means is of primary importance. Existing models used to analyze the performance of RC beam-to-column joints have either been developed for modern, well-detailed joints or are simplified so that they do not capture a broad range of phenomena.
The present study is aimed to extend a modeling technique based on the nonlinear truss analogy to the analysis of RC beam-to-column joints under cyclic loads. Steel and concrete elements were arranged into a lattice truss structure with zero-length bond-slip springs connecting them. A new steel model was implemented to more accurately capture the constitutive behavior of reinforcing bars. The joint modeling approach captured well the shear response of the joint. It also provided a good indication of the distribution of forces within the joint.
The model was validated against three recently tested beam-column subassemblies. These tests represented the detailing practice of poorly-detailed RC moment frames. The analytical results were in good agreement with the experimental data in terms of initial stiffness, strength and damage pattern through the joint.Master of Science
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Zerkane, Ali S. H. "Cyclic Loading Behavior of CFRP-Wrapped Non-Ductile Reinforced Concrete Beam-Column Joints." PDXScholar, 2016. http://pdxscholar.library.pdx.edu/open_access_etds/3000.
Full textAbstract:
Use of fiber reinforced polymer (FRP) material has been a good solution for many problems in many fields. FRP is available in different types (carbon and glass) and shapes (sheets, rods, and laminates). Civil engineers have used this material to overcome the weakness of concrete members that may have been caused by substandard design or due to changes in the load distribution or to correct the weakness of concrete structures over time specially those subjected to hostile weather conditions. The attachment of FRP material to concrete surfaces to promote the function of the concrete members within the frame system is called Externally Bonded Fiber Reinforced Polymer Systems. Another common way to use the FRP is called Near Surface Mounted (NSM) whereby the material is inserted into the concrete members through grooves within the concrete cover. Concrete beam-column joints designed and constructed before 1970s were characterized by weak column-strong beam. Lack of transverse reinforcement within the joint reign, hence lack of ductility in the joints, and weak concrete could be one of the main reasons that many concrete buildings failed during earthquakes around the world. A technique was used in the present work to compensate for the lack of transverse reinforcement in the beam-column joint by using the carbon fiber reinforced polymer (CFRP) sheets as an Externally Bonded Fiber Reinforced Polymer System in order to retrofit the joint region, and to transfer the failure to the concrete beams. Six specimens in one third scale were designed, constructed, and tested. The proposed retrofitting technique proved to be very effective in improving the behavior of non-ductile beam-column joints, and to change the final mode of failure. The comparison between beam-column joints before and after retrofitting is presented in this study as exhibited by load versus deflection, load versus CFRP strain, energy dissipation, and ductility.
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Deaton, James B. "Nonlinear finite element analysis of reinforced concrete exterior beam-column joints with nonseismic detailing." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47538.
Full textAbstract:
This research investigated the behavior of nonseismically detailed reinforced concrete exterior beam-column joints subjected to bidirectional lateral cyclic loading using nonlinear finite element analysis (NLFEA).
Beam-column joints constitute a critical component in the load path of reinforced concrete buildings due to their fundamental role in integrating the overall structural system. Earthquake reconnaissance reports reveal that failure of joints has contributed to partial or complete collapse of reinforced concrete buildings designed without consideration for large lateral loads, resulting in significant economic impact and loss of life. Such infrastructure exists throughout seismically active regions worldwide, and the large-scale risk associated with such deficiencies is not fully known. Computational strategies provide a useful complement to the existing experimental literature on joint behavior and are needed to more fully characterize the failure processes in seismically deficient beam-column joints subjected to realistic failure conditions. Prior to this study, vulnerable reinforced concrete corner beam-column joints including the slab had not been analyzed using nonlinear finite element analysis and compared with experimental results.
The first part of this research focused on identification and validation of a constitutive modeling strategy capable of simulating the behaviors known to dominate failure of beam-column joints under cyclic lateral load using NLFEA. This prototype model was formulated by combining a rotating smeared crack concrete constitutive model with a reinforcing bar plasticity model and nonlinear bond-slip formulation. This model was systematically validated against experimental data, and parametric studies were conducted to determine the sensitivity of the response to various material properties. The prototype model was then used to simulate the cyclic response of four seismically deficient beam-column joints which had been previously evaluated experimentally. The simulated joints included: a one-way exterior joint, a two-way beam-column exterior corner joint, and a series of two-way beam-column-slab exterior corner joints with varying degrees of seismic vulnerability. The two-way corner joint specimens were evaluated under simultaneous cyclic bidirectional lateral and cyclic column axial loading. For each specimen, the ability of the prototype model to capture the strength, stiffness degradation, energy dissipation, joint shear strength, and progressive failure mechanisms (e.g. cracking) was demonstrated.
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Li, Jing, and 李靜. "Effects of diagonal steel bars on performance of interior beam-column joints constructed with high-strength concrete." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B31244464.
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Wong, Ho Fai. "Shear strength and seismic performance of non-seismically designed reinforced concrete beam-column joints /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202005%20WONG.
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Spyrou, Spyros. "Development of a component based model of steel beam-to-column joints at elevated temperatures." Thesis, University of Sheffield, 2002. http://etheses.whiterose.ac.uk/12830/.
Full textAbstract:
The response of steel-framed structures to applied loading depends to a large degree on the behaviour of the joints between the columns and beams. Traditionally designers have assumed that these joints act either as 'pinned', with no ability to transmit moments from beam to column, or as 'rigid', providing perfect continuity between the connected members. Advances in analysis, and developments in modem codes of practice, permit designers to account for the real behaviour of steel joints where this is known or can be predicted. Even though experimental studies of joints conducted at many research centres around the world have provided a large bank of test data, the vast number of variables in joints (beam and column sizes, plate thicknesses, bolt sizes and spacing, etc.) often means that data for a specific joint arrangement does not exist. As a result, researchers have turned their attention to ways of predicting the behaviour of such joints. One approach which has gained acceptance is based on the "Component Method" in which overall joint behaviour is assumed to be produced by the responses of its various simpler components. To date, data on the response of joints at elevated temperatures has been gathered from full-scale furnace tests on cruciform arrangements, which have concentrated exclusively on moment-rotation behaviour in the absence of axial thrusts. However, when steel-framed structures are subjected to fire, the behaviour of the joints within the overall frame response is greatly affected by the high axial forces which are created by restraint to the thermal expansion of unprotected beams. If momentrotation- thrust surfaces were to be generated this process would require prohibitive numbers of complex and expensive furnace tests for each joint configuration. The alternative, and more practical, method is to extend the Component Method to the elevated-temperature situation. The basic theme of the Component Method is to consider any joint as an assembly of individual simple components. Each of these components is simply a non-linear spring, possessing its own level of strength and stiffness in tension, compression or shear, and these will degrade as its temperature rises. The main objective of this study was to investigate experimentally and analytically the behaviour of tension and compression zones of end-plate connections at elevated temperatures. A series of experiments has been carried out and a simplified analytical model has been developed, and this has been validated against the tests and against detailed finite element simulations. The simplified model is shown to be very reliable for this very common type of joint, although similar methods will need to be developed for other configurations. The principles of the Component Method can be used directly in either simplified or finite element modelling, without attempting to predict of the overall joint behaviour in fire, to enable semi-rigid behaviour to be taken into account in the analytical fire engineering design of steel-framed and composite buildings.
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Engindeniz, Murat. "Repair and strengthening of Pre-1970 reinforced concrete corner beam-column joints using CFRP composites." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24808.
Full textAbstract:
Thesis (Ph.D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2008.Committee Co-Chair: Kahn, Lawrence F.; Committee Co-Chair: Zureick, Abdul-Hamid; Committee Member: Armanios, Erian A.; Committee Member: Gentry, Russell T.; Committee Member: Leon, Roberto T.
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Ngo, Tang Tuan. "Development and Design of Non-corrosive Precast Dry Beam-column Joints with Fibre-reinforced Polymer." Thesis, Curtin University, 2021. http://hdl.handle.net/20.500.11937/86212.
Full textAbstract:
This dissertation successfully developed new sustainable and resilient precast beam-column joints with excellent performance under hazardous load, i.e. earthquake and impact loading. The proposed joints provide numerous advantages that cannot be found in typical monolithic beam-column joints including faster construction, better quality control, easier replacing and repairing of damaged components, recycling industry by-product materials, and unsusceptible to corrosion. Besides experiments, analytical models and design procedures of the new joints have been developed for practical applications.
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Schrauben, Corey S. "Behavior of full-scale bolted beam-to-column T-stub and clip angle connections under cyclic loading." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/20013.
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Akguzel, Umut. "Seismic Performance of FRP Retrofitted Exterior RC Beam-Column Joints under Varying Axial and Bidirectional Loading." Thesis, University of Canterbury. Civil and Natural Resources Engineering, 2011. http://hdl.handle.net/10092/5993.
Full textAbstract:
Most of the experimental studies available in literature on the seismic assessment and retrofit of existing, poorly detailed, reinforced concrete (RC) beam-column joints typical of pre-1970s construction practice have concentrated on the two-dimensional (2D) response, using unidirectional cyclic loading testing protocols and a constant column axial load. Even more limited information is available on the performance of corner three-dimensional (3D) RC beam-column joints with substandard detailing subjected to a bidirectional-loading regime. In addition, little effort has been dedicated to the development of simple but reliable analysis and design procedure for FRP-strengthened joints.
This thesis aims to (1) investigate the effects of varying axial and bidirectional loading on the seismic performance of deficient exterior RC beam-column joints before and after retrofit and (2) develop performance-based seismic assessment and FRP-based retrofit procedures for exterior and corner beam-column joints. For this purpose, following a critical review on the seismic vulnerability of both existing and retrofitted exterior and corner beam-column joints under varying and bidirectional loading demands, a comprehensive experimental programme along with analytical and numerical studies are carried out.
A performance-based retrofit approach was adopted in order to achieve the desired ductile failure mode by modifying the hierarchy of strength within the beam-column joint system. In order to achieve this, existing retrofit design methodology available in literature was refined and a step-by-step procedure was proposed for the assessment of the as-built and proceeding retrofit design of FRP-retrofitted exterior beam-column joints. In addition, the role and importance of accounting for the correct demand conditions (e.g., the variation of axial loads) in the assessment of the existing joint and the design of the FRP retrofit scheme were discussed. In order to assist the retrofit design and assessment procedure a semi-empirical analytical model was developed to evaluate the joint shear resistance after FRP retrofit. Both the proposed assessment methodology and design procedure along with the analytical procedure were verified by experimental studies performed in this thesis and experimental tests available in the literature. Parametric analyses were also carried out to indicate the
Umut Akguzel Seismic Performance of FRP Retrofitted Exterior RC Beam-Column Joints
under Varying Axial and Bidirectional Loading
effectiveness of strengthening with different materials, configurations and failure limit states.
The feasibility and efficiency of a retrofitting intervention using GFRP composites were investigated based on the quasi-static cyclic tests conducted on four 2D exterior (plane frame) and two 3D corner (space frame) RC joints. All specimens were of 2/3 scale, designed according to pre-1970s construction practice. The properties of the specimens are summarized briefly as follows:
(1) Specimen 2D1 was tested under varying axial load as an exterior 2D benchmark unit;
(2) Specimen 2D2 was tested under constant axial load with minimum retrofit solution designed according to the proposed methodology;
(3) Specimen 2D3 was tested under varying axial load with the same retrofit scheme adopted in 2D2; (4) Specimen 2D4 was tested under varying axial load with improved retrofit scheme;
(5) Specimen 3D1 was tested under bidirectional loading with varying axial load as a benchmark;
(6) Specimen 3D2 was tested under bidirectional loading with varying axial load with improved retrofit scheme adopted in Specimen 2D4.
The test outcomes highlighted the potentially unconservative effects of neglecting the actual multiaxial load demand, when assessing the behaviour of existing beam-column joints and designing a proper retrofit intervention. Corner beam-column joints within a frame building were confirmed to be particularly vulnerable. However, with an adequate retrofit design accounting for the multiaxial load effects, the implemented retrofit solutions provided the necessary improvements of the behaviour of the as-built specimens. This resulted in the development of a more appropriate hierarchy of strength with the formation of plastic hinges in the beam and protection of the weaker mechanisms. The experimental findings were also used to identify the critical damage limit states and engineering parameters to be adopted within the framework of performance-based seismic retrofit design.
In addition to the experimental and analytical studies, FEM numerical studies based on microplane concrete model approach were carried out. Three-dimensional finite element (FE) models for retrofitted 2D exterior joint (Specimen 2D2) and as-built 3D corner joint (Specimen 3D1) were developed and analysed. The analysis results showed good agreement with the experimental results.
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Wang, Yandong. "Experimental and numerical investigation of panel zone behavior and yielding mode classification for steel beam-column joints." Kyoto University, 2020. http://hdl.handle.net/2433/253267.
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Yang, Cheng-Ta, and 楊政達. "Retrofitting of Non-ductile ReinforcedConcrete Exterior Beam-Column Joints." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/81398583791633102352.
Full textAbstract:
碩士國立中央大學
土木工程研究所
90
This experiment was mainly aimed at exploring the advantage of retrofitting non-ductile and low-strength RC exterior beam-column joint by Concrete Jacketing and Steel Jacketing. A discussion was made through the differences in stiffness, ductility and joint shear degradation between benchmark and retrofitted specimen. From the experiment results, we found that Concrete Jacketing scheme could efficiently improve the joint shear strength and make beam plastic hinge develop before joint shear failure, which is required by the seismic resistant design code and greatly improve the joint shear strength better than Steel Jacketing scheme. Finally, from the behavior of joint shear degradation of retrofitted specimen, a retrofitted recommendation of Concrete Jacketing and Steel Jacketing is proposed for reference on further RC retrofitting schemes in Taiwan.
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Gao, Wun-liang, and 高文良. "Anchorage Behavior of Headed Bar in Beam-Column Joints." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/tzg32e.
Full textAbstract:
碩士國立臺灣科技大學
營建工程系
100
In this study, headed bars are adopted to replace traditional standard hooks for avoiding reinforcement crowding in the beam-column joints. Seven full size experiments (four of them are interior beam-column connections and three of them are exterior beam-column connections) were conduct to investigate the influence of headed bars on beam-column joints. Not only to understand the anchorage behavior of headed bars in beam-column joints, but to comprehend the effect on flexure moment of beams. The issue on whether the performance of beam-column joints with different arrangements of head bars satisfy the seismic requirement is also discussed. For interior beam-column joints with two types of arrangement, i.e., butt and splices, the strength and ductility of the beam-column joints are found to be satisfactory. Additionally, for butt arrangement with enough anchorage length, the yielding of reinforcement and crush of concrete at beam end are obvious during incremental loading vertically. For the exterior beam-column joints, this study recommends the seismic resistant anchorage length of headed bars should be the ACI 318-08 provision multiplied by 1.23 times on condition that the clear spacing of headed bars is 2.2db, the beam-column joint belongs to the low shear ratio and strong column-weak beam pattern.
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Huang, Chien Hsun, and 黃建勳. "A Study of Post-Tensioned Precast Beam-Column Joints." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/69827241885384720033.
Full textAbstract:
碩士國立臺灣科技大學
營建工程系
93
In this research, five reinforced concrete specimens with or without energy dissipating devices were tested to study the energy dissipating capacity and the damage of concrete. Three exterior joint specimens LPTC, HPTC and HPTC-M used steel plates as the energy dissipating device. Interior joint specimen PTC had different lateral steel configurations for the left and right connected beams. Another interior joint specimen Hybrid PTC used partially unbonded mild steel bars as the energy dissipating device. The RC column dimensions were 650×650 mm and the RC beam dimensions were 500×600 mm. The spacing of lateral reinforcement #4 was 100mm in the region of beam-column joint to avoid shear failure. The ends of columns were held with actuators to simulate hinge ends. The force was applied to beam ends under displacement control. The displacement followed a cyclic loading history from small drift levels to large drift levels. The energy dissipating devices suggested in this research can be used in the unbonded post-tensioned precast reinforced concrete beam-column joints and the specimens performed good self-centering ability and good energy dissipating ability. The steel plates used to protect the contact surfaces of beam-column joints caused the concrete only had minor cracks. The steel plates used as energy dissipators need special cares to prevent their buckling and sliding.
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Hasaballa, Mohamed Hassanein. "Seismic behaviour of exterior GFRP-reinforced concrete beam-column joints." 2010. http://hdl.handle.net/1993/21620.
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Kao, Chi-Jou, and 高啟洲. "Retrofitting of Non-Ductile Reinforced Concrete Interior Beam-Column Joints." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/90385844178283058660.
Full textAbstract:
碩士國立中央大學
土木工程研究所
90
This experiment was mostly aimed at the feasibility of retrofitting non-ductile and low-strength interior beam-column joint by Concrete Jacketing and Steel Jacketing, and a discussion was made through the differences in stiffness, ductility, and joint shear degradation between benchmark and retrofitted specimen. In the respect of ductility and energy absorption, JI2 Concrete Jacketing and JI4 Steel Jacketing schemes could both prevent benchmark from unexpected joint shear failure before beam plastic hinges developed and respectively upgraded its own ductility by 30% and 77%. However, both JI2 and JI4 specimen’s failure modes are joint shear failure at the end of the test, and their retrofitted ductility did not reach 4, which is the target of our retrofitting scheme. Therefore, further research is needed. Finally, according to the discussed behavior of joint shear degradation, we provided beam-column joint retrofitting scheme recommendations, which can be referenced for further research on beam-column joint retrofitting in Taiwan.
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LEI, IAR-FAI, and 李日暉. "Shear Properties of Beam-Column Joints Using High Strength Concretes." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/40501011944408117484.
Full textAbstract:
碩士國立中央大學
土木工程學系
86
The differences of provisions of the current ACI 318-95joint. Code and the NZS 3101-1995 Code, namely in the amount oftransverse reinforcement within the joints, will affect theseismic performance of the structures deeply. Because of thesetwo Codes are based on normal-strength concrete. Therefore, Theobjective ofthis study is focused on the ACI 318-95 Code andthe NZS 3101-1995 Code when apply high-strength concrete tobeam-column joints. Four beam-column joints specimens accordingto the Codes were tested. Three of them are the high- strengthconcrete specimens and the other one is normal- strengthspecimen. Test results indicated that the high-strength concretespecimens designed according to the ACICode would overly conservative and created congestion of transverse reinforcementin the joint , difficult to construct. Once the specimensconforming to theNZS Code could improve the seismic performanceof the structures and would notresult in congestion of steelwithin the joint.
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Huwang, Shih-Chi, and 黃士旗. "Seismic Assessment on Rehabilitation of Damaged RC Beam-Column Joints." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/88347851316387959807.
Full textAbstract:
碩士國立中央大學
土木工程研究所
91
This experiment was mainly aimed at exploring feasibility of retrofitting damaged beam-column joint by wire concrete jacketing,and a discussion was made through the differences in stiffness, ductility, joint shear degradation between each retrofitted specimen。 From the experiment results,it was found that wire concrete jacketing scheme could improve the joint shear strength and make beam plastic hinge develop before joint shear failure。Howerver, the benefit of retrofitting does not come up to the target of the study because the split occurred in the interface between new and old concrete。It will improve the benefit of retrofitting by wire concrete jacketing if using anchoring method to prevent the split condition。
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Lee, Horng-Ren, and 李宏仁. "Seismic Parametric Study of Reinforced Concrete Corner Beam- Column Joints." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/19639526332597332932.
Full textAbstract:
碩士國立台灣工業技術學院
營建工程技術研究所
85
The current design procedures of the beam-column joints are not convincing because of poor understanding of joint behavior. The ACI 318-95 code sets up the limits of the individual design parameter to insure indirectly the satisfaction of the demand of structural behavior based on the test results with the normal strength concrete (NSC). However, with the development of technology of the high strength concrete (HSC), whether the limits of design parameters in the ACI code are suitable is still controversial. This research first summarized the deign codes of United States, Japan, and New Zealand, and the different tendency of design parameters with increasing concrete strength among different codes was discussed. We found that the demands of transverse reinforcement in the joint region among codes are obvious different. Then, a data-bank composed of the test results of 89 exterior beam-column joints was established. Further, we defined the standard of failure-mode classification, based on the performance criteria of joint behavior. According to the investigation on the design parameters of HSC and NSC corner beam-column joints, we recommended the ACI code to revise the provision on the effective shear area of the exterior joint. With this modification, the demand of transverse reinforcement for the ACI code can possibly reduce 25%. Besides, the data-bank is used to check a joint shear-resistant model based on the diagonal strut concept, and it is found that the model is unsuitable for the beam-column joint with hightrength concrete.
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Santiago, Aldina Maria da Cruz. "Behaviour of beam-to-column steel joints under natural fire." Doctoral thesis, 2008. http://hdl.handle.net/10316/7543.
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Hoffschild, Thomas E. "Retrofitting beam-to-column joints for improved seismic performance microform." Thesis, 1992. http://hdl.handle.net/2429/2461.
Full textAbstract:
Before the 1970's, most codes for the design of reinforced concrete structures did not include provisions for ductility during seismic events was not prevalent in most codes. The guidelines that did exist were minimal, and often left a fair amount of room for interpretation by the design engineer. Hence, many of the reinforced concrete structures designed during that time are suspect under today's more stringent design guidelines. Moreover, even the present designs are often deficient and vary from building to building and from jurisdiction to jurisdiction.
This report is a presentation of the findings of an experimental study to evaluate a method of retrofit which addresses a particular weakness that is often found in reinforced concrete structures, namely the lack of sufficient reinforcement in and around beam-to-column joints. Many of these structures lack the required confining reinforcement within the joints and in adjoining beams and columns. The result is a reinforced concrete framethat is weak in the joint area and lacks sufficient ductility during a seismic event.
The proposed retrofit method consists of encasing the reinforced concrete joint with a grouted steel jacket that provides confinement to the joint area, and imparts ductility to the frame. In this study, two styles of retrofit jacket were tested: a circular steel tube and a rectangular casing. It was found that circular steel jackets have the advantage of providing direct concrete confinement and, as well, of furnishing a ductile force transfer mechanism through the jacket itself, but are also more difficult and expensive to fabricate than rectangular jackets. Although rectangular jackets do not provide the same degree of concrete core confinement as circular jackets, the amount available seems sufficient to prevent damage in the joint area. The load transfer mechanism of the rectangular jackets was found to be adequate in withstanding the loads and deflections typical for seismic events.
In this thesis, the two jacket styles are evaluated for strength, stiffness and ductility, and their relative merits are discussed.