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1.
Reinforced concrete columns with insufficient transverse reinforcement and non‐seismic reinforcement details are vulnerable to brittle shear failure and to loss of axial load carrying capacity in the event of a strong earthquake. In this paper, a procedure is presented after examining the application of two macro models for displacement‐based analysis of reinforced concrete columns subjected to lateral loads. In the proposed model, lateral load‐deformation response of the column is simulated by estimating flexural and shear deformation components separately while considering their interaction and then combining these together according to a set of rules depending upon column's yield, flexural and shear strengths. In addition, lateral deformation caused by reinforcement slip in beam–column joint regions and buckling of compression bars are taken into account and considered in the analysis. Implementation of the proposed procedure produces satisfactory lateral load–displacement relationships, which are comparable with experimental data. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
2.
Finite element analysis of damage and failure of reinforced concrete members under earthquake loading 
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下载免费PDF全文 This paper presents a three‐dimensional analysis framework, based on the explicit finite element method, for the simulation of reinforced concrete components under cyclic static and dynamic loading. A recently developed triaxial constitutive model for concrete is combined with a material model for reinforcing steel which can account for rupture due to low‐cycle fatigue. The reinforcing bars are represented with geometrically nonlinear beam elements to account for buckling of the reinforcement. The strain penetration effect is also accounted for in the models. The modeling scheme is used in a commercial finite element program and validated with the results of experimental static and dynamic tests on reinforced concrete columns and walls. The analyses are supplemented with a parametric study to investigate the impact of several modeling assumptions on the obtained results. 相似文献
3.
横向预应力混凝土梁的抗剪性能试验研究 总被引：1，自引：0，他引：1
通过4根加配横向预应力筋的钢筋混凝土梁和1根普通钢筋混凝土梁的对比试验,初步考察了横向预应力筋对提高钢筋混凝土梁抗剪性能的良好效果。研究结果表明:(1)加配横向预应力筋并施加适当预应力之后,钢筋混凝土梁的抗剪承载力提高70%以上,即使在不施加预应力的情况下,梁的抗剪承载力也约有40%的增长;(2)在横向预应力筋的总截面面积一定的情况下,采用直径较小的横向预应力筋和较小的间距,更有助于改善钢筋混凝土梁的破坏形态。 相似文献
4.
This experimental study investigates the effectiveness of crossed inclined bars (X‐bars) as joint shear reinforcement in exterior reinforced concrete beam–column connections under cyclic deformations. Test results of 20 joint subassemblages with various reinforcement ratios and arrangements including X‐bars in the joint area are presented. The X‐type, non‐conventional reinforcement is examined as the only joint reinforcement and in combination with common stirrups or vertical bars. The experimental results reported herein include full loading cycle curves, energy dissipation values and a categorization of the observed damage modes. Based on the comparisons between the overall hysteretic responses of the tested specimens, it is deduced that joints with X‐bars exhibited enhanced cyclic performance and improved damage mode since a distinct flexural hinge was developed in the beam–joint interface. Further, the combination of crossed inclined bars and stirrups in joint area resulted in enhanced hysteretic response and excellent performance capabilities of the specimens. However, in some specimens with X‐bars as the only joint shear reinforcement, the deformations of the bent anchorage of the beam's bars caused considerable damages at the back of the joint area. Discussion for a potential replacement of the joint stirrups with X‐type reinforcement in some cases of exterior joints is also included. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
5.
Mohammadreza Moharrami Ioannis Koutromanos Marios Panagiotou Sadik Can Girgin 《地震工程与结构动力学》2015,44(5):677-694
This paper uses nonlinear truss models for the analysis of shear‐dominated reinforced concrete (RC) columns subjected to cyclic loading. A previously established method, aimed to the analysis of RC walls, is enhanced to allow simulations of column members. The concrete constitutive equations are modified to account for the contribution of the aggregate interlock to the shear resistance. Additionally, an equation is proposed to determine the inclination angle of the diagonal members in the truss models. The modeling approach is validated using the results of quasi‐static and dynamic tests on shear‐dominated RC columns. The combination of predictive capabilities and conceptual simplicity establishes truss‐based models as an attractive approach for the systematic analysis of shear‐dominated RC frame construction. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
6.
This paper deals with the assessment of the seismic response of a portal frame pier belonging to an old reinforced concrete viaduct. A series of tests, consisting of cyclically imposed displacements, were carried out on three 1:4 scale mock‐ups. The objective of the experimental campaign is twofold: (1) identification and evaluation of the local failure mechanisms and (2) calibration of a numerical model including all observed nonlinear phenomena. The experimental results show that the shear strength of the transverse beam and of the beam–column joints characterizes the post‐elastic behavior of the piers. Other phenomena, like bond‐slip and buckling of the longitudinal bars of the columns, typical of old reinforced concrete structures have also been observed. Finally, a numerical model, built in OpenSEES, was calibrated to reproduce in a satisfactory way the experimental results and to provide a reliable tool for the evaluation of the seismic response of the pier. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
7.
A numerical process that simulates crack propagation in reinforced concrete through post‐crack stress redistribution is presented. This process is developed within the context of the smeared crack approach. Continuity and orientation of the reinforcing bar components are automatically recognized in the pre‐processing stage. The process explicitly outputs crack widths by computing the bond slips along reinforcement, without imposing any additional nodes between the reinforcement and concrete. The process is incorporated with a finite element algorithm, and the validation is investigated through sample 3D static analyses of nine concrete specimens subjected to monotonic shear and flexure loads. These specimens contain relatively well‐distributed steel bars and fiber reinforced polymer (FRP) sheets of reinforcement ratio from 0.11 to 0.57%. The analyses predict the crack patterns and crack widths well, although some disagreements are found between the test and the analysis results. The proposed process outputs discrete, continuous in crack directions, and element boundary‐free crack patterns. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
8.
A numerical procedure for a dynamic non-linear finite element analysis is proposed here to analyse three-dimensional reinforced concrete shear wall structures subjected to earthquake motions. A shear wall is modelled as a quasi-three dimensional structure which is composed of plane elements considering the in-plane stiffness of orthogonal flange panels. The proposed constitutive model is based on the non-linearity of reinforcement and concrete in which the tension stiffening in tension and the degradation of stiffness and strength in compression of concrete after cracking are considered. The acceleration-pulse method, which is a kind of explicit analytical procedure, is employed to solve the non-linear dynamic equations, where the dynamic equation can be solved without stiffness matrix and so the iterative procedure is not necessary for descending portion of stress–strain relationship caused by cracking and softening after compressive strength in concrete. The damping effect is considered by assuming equivalent viscous damping which can give good cyclic behaviours of inertia force vs. displacement relationships. This analytical method was applied to a test specimen of a reinforced concrete shear wall with a H-shaped section which was vibrated up to failure by using a large-scale shaking table with high -performance in Japan. The test was performed as one of the dynamic model tests for evaluation of seismic behaviour of nuclear reactor buildings. The calculations were performed sequentially from the elastic range to failure. The comparison with the test results shows that this approach has good accuracy. © 1997 by John Wiley & Sons Ltd 相似文献
9.
Three‐dimensional beam–truss model for reinforced concrete walls and slabs – part 2: modeling approach and validation for slabs and coupled walls 下载免费PDF全文
下载免费PDF全文 A three‐dimensional beam–truss model (BTM) for reinforced concrete (RC) walls that explicitly models flexure–shear interaction and accurately captures diagonal shear failures was presented in the first part of this two‐paper series. This paper extends the BTM to simulate RC slabs and coupled RC walls through slabs and beams. The inclination angle of the diagonal elements for coupled RC walls is determined, accounting for the geometry of the walls and the level of coupling. Two case studies validate the model: (1) a two‐bay slab–column specimen experimentally tested using cyclic static loading and (2) a five‐story coupled T‐wall–beam–slab specimen subjected to biaxial shake table excitation. The numerically computed lateral force–lateral displacement and strain contours are compared with the experimentally measured response and observed damage. The five‐story specimen is characterized by diagonal shear failure at the bottom story of the walls, which is captured by the BTM. The BTM of the five‐story specimen is used to study the effects of coupling on shear demand for lightly reinforced RC coupled walls. The effect of mesh refinement and bar fracture of non‐ductile transverse reinforcement is studied. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
10.
The seismic damages commonly observed on beam–column joints of old reinforced concrete structures, built with plain bars and without proper detailing, justifies the need to further study the behaviour of this type of structures. The response of these structures when loaded cyclically, as occurs during the earthquakes, is partially controlled by the bond properties between the reinforcing bars and the surrounding concrete. This paper presents the results of an experimental campaign of unidirectional cyclic tests carried out on six full‐scale beam–column joints built with plain bars. These joint specimens are representative of existing reinforced concrete structures, that is, built without adequate reinforcement detailing for seismic demands. For comparison, an additional specimen is built with deformed bars and tested. The seven specimens are designed and detailed to allow the investigation of the influence of bond properties, lapping of the longitudinal bars in columns and beams, bent‐up bars in the beams, slab contribution and concrete strength. The lateral force–drift relationships, global dissipated energy evolution, contribution of the joint, beams and columns to the global dissipated energy, ductility, equivalent damping, final damage observed, homogenized reinforced concrete damage index, displacement components, curvature evolutions and Eurocode requirements are presented and discussed. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
11.
针对钢筋混凝土高层框支剪力墙结构抗震性能差的缺点,提出采用型钢混凝土（SRC）梁柱框支剪力墙,试验结果表明了其良好的抗震性能。提出了框支剪力墙结构地震反应简化分析模型,将结构简化为由墙单元和框支单元组成的弹簧体系,墙单元采用二元件模型。推导了框支单元刚度矩阵,基于理论公式和试验结果给出了框支单元恢复力模型。根据提出的简化模型,编制了结构地震反应时程分析程序。程序计算结果与ETABS分析结果及振动台试验结果吻合较好,为进一步对SRC框支剪力墙结构进行地震反应分析提供了理论基础。 相似文献
12.
The feasibility and efficiency of a seismic retrofit solution for existing reinforced concrete frame systems, designed before the introduction of modern seismic‐oriented design codes in the mid 1970s, is conceptually presented and experimentally investigated. A diagonal metallic haunch system is introduced at the beam–column connections to protect the joint panel zone from extensive damage and brittle shear mechanisms, while inverting the hierarchy of strength within the beam–column subassemblies and forming a plastic hinge in the beam. A complete step‐by‐step design procedure is suggested for the proposed retrofit strategy to achieve the desired reversal of strength hierarchy. Analytical formulations of the internal force flow at the beam–column‐joint level are derived for the retrofitted joints. The study is particularly focused on exterior beam–column joints, since it is recognized that they are the most vulnerable, due to their lack of a reliable joint shear transfer mechanism. Results from an experimental program carried out to validate the concept and the design procedure are also presented. The program consisted of quasi‐static cyclic tests on four exterior, ? scaled, beam–column joint subassemblies, typical of pre‐1970 construction practice using plain round bars with end‐hooks, with limited joint transverse reinforcement and detailed without capacity design considerations. The first (control specimen) emulated the as‐built connection while the three others incorporated the proposed retrofitted configurations. The experimental results demonstrated the effectiveness of the proposed solution for upgrading non‐seismically designed RC frames and also confirmed the applicability of the proposed design procedure and of the analytical derivations. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
13.
Failure simulation of shear‐critical RC columns with non‐ductile detailing under lateral load 下载免费PDF全文
下载免费PDF全文 Reinforced concrete columns with non‐ductile detailing typically exhibit a softening behavior characterized by severe degradation when subjected to cyclic lateral loads. Whether the response is brittle or ductile, shear failure occurs with an inclined through crack along which sliding occurs coupled with loss of horizontal and vertical load‐bearing capacity of the member. The rapid loss of resistance after the peak strength is reached is because of one or more of the following local failure mechanisms: brittle failure of poorly confined concrete; buckling of longitudinal reinforcing bars because of lack of adequate transverse reinforcement or following opening of stirrups after spalling of cover concrete; bond failure. In this study, a modeling strategy to build a detailed 3D finite element model capable of capturing all of the above‐mentioned local failure mechanisms is presented. In particular, a steel–concrete interface model for representing the interaction within the member between concrete core, cover and longitudinal and transverse reinforcement is proposed. Comparison with results of an experimental test of a shear‐sensitive column demonstrates the effectiveness of the simulation up to failure of the element. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
14.
铝合金筋与混凝土的粘结性能是影响铝合金配筋新型混凝土梁承载力的重要因素。对9根铝合金配筋混凝土梁和2根钢筋混凝土对比梁进行了静载试验,分析混凝土梁在加载过程中的裂缝发展情况,基于缝宽-滑移理论研究试验梁的粘结性能。研究结果表明:同级荷载作用下,钢筋混凝土梁的裂缝宽度小于铝合金配筋混凝土梁,钢筋与混凝土的粘结性能优于铝合金与混凝土的粘结性能;混凝土梁中纵筋所受拉力,实质上是混凝土开裂后,单元体内部粘结力的合力;纵筋与混凝土的粘结滑移量与粘结力直接相关,可通过代数和微积分计算得到二者的对应关系。 相似文献
15.
This paper focuses on analyzing the nonlinear seismic response of high‐arch dams with cantilever reinforcement strengthening. A modified embedded‐steel model is presented to evaluate the effects of the strengthening measure on alleviating the extension and opening of cracks under strong earthquakes. By stiffening reinforced steel, this model can easily consider the steel–concrete interaction for lightly reinforced concrete (RC) members without the need of dividing them into RC and plain concrete zones. The new tensile constitutive relations of reinforced steel are derived from the load–deformation relationship of RC members in direct tension. This model has been implemented in the finite element code and its applicability is verified by two numerical simulations for RC tests. Subsequently, numerical analyses for a 210‐m high‐arch dam (Dagangshan arch dam) are conducted with and without the presence of cantilever reinforcement. Numerical results show that reinforcement strengthening can reduce the nonlinear response of the arch dam, e.g. joint opening and crest displacement, and limit the extension and opening width of concrete cracks. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
16.
Numerous non‐ductile reinforced concrete (RC) buildings with little or no shear reinforcement in beam‐column joints can be found in regions of moderate seismicity. To strengthen such substandard beam‐column joints, this study proposes a method in which RC wing walls are installed beside existing columns, which overcomes the lack of realistic strengthening methods for congested connections in RC buildings. The proposed strengthening mechanism improves the joint moment capacity by utilizing tension and compression acting on the beam–wing wall boundaries; thus, brittle joint hinging failure is prevented. Three 3/4‐scale RC exterior beam‐column joint specimens without shear reinforcement, two of which were strengthened by installing wing walls with different strengthening elements, were fabricated and tested. The test results verified the effectiveness of the proposed strengthening method and the applicability of this method to seismically substandard beam‐column joints. © 2017 The Authors. Earthquake Engineering & Structural Dynamics Published by John Wiley & Sons Ltd. 相似文献
17.
Reinforced concrete (RC) structures in low to moderate seismic regions and many older RC structures in high seismic regions include columns with steel reinforcement details not meeting the requirements of modern seismic design codes. These columns typically fail in shear or in a brittle manner and their behavior must be accurately captured when RC structures are modeled and analyzed. The total lateral displacement of a low ductility or shear critical RC column can be represented as the sum of three displacement components: (1) flexural displacement, (2) displacement due to slippage of the reinforcing bars at column ends, and (3) shear displacement. In this study, these three displacement components are separately modeled and then combined together following a proposed procedure based on the expected overall behavior of the column and its failure mechanism. A simplified slip model is proposed. The main objective of this research is to develop an easy-to-apply method to model and capture the cyclic behavior of RC columns considering the shear failure mechanism. The proposed model is validated using the available data from RC column and frame experiments. 相似文献
18.
基于通用有限元软件ABAQUS,分别在准静态和动态加载条件下,对不同剪跨比和箍筋率的钢筋混凝土柱进行了数值模拟。对比现有试验结果发现,ABAQUS的模拟效果与试验结果吻合较好;加载速率的影响随着剪跨比和箍筋率的增大而降低;钢筋混凝土柱的峰值承载力随着加载速率增大而增大的趋势明显,刚度无明显变化,延性比趋于稳定。因此,在进行地震作用下钢筋混凝土结构的抗震分析时,对加载速率的影响效应要给予足够的考虑。 相似文献
19.
This work focuses on the modelling issues related to the adoption of the pushover analysis for the seismic assessment of existing reinforced concrete (RC) structures. To this purpose a prototype reference structure, one of the RC shear walls designed according to the multi‐fuse concept and tested on shaking table for the CAMUS project, is modelled at different levels of refinement. The meso‐scale of a stiffness‐based fibre element and the micro‐scale of the finite element (FE) method are herein adopted; in the latter separate elements are adopted for the concrete, the steel and the steel–concrete interface. This first of the two companion papers presents in detail the wall under study, illustrating the design philosophy, the geometry of the wall, the instrumentation set‐up and the test programme. The two modelling approaches are then described; the most important points in terms of element formulation and constitutive relations for materials are presented and discussed for each approach, in the light of the particular design of the wall and of its experimental behaviour. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
20.
Static inelastic analysis of RC shear walls 总被引：1，自引：0，他引：1
A macro-model of a reinforced concrete (RC) shear wall is developed for static inelastic analysis. The model is composed of
RC column elements and RC membrane elements. The column elements are used to model the boundary zone and the membrane elements
are used to model the wall panel. Various types of constitutive relationships of concrete could be adopted for the two kinds
of elements. To perform analysis, the wall is divided into layers along its height. Two adjacent layers are connected with
a rigid beam. There are only three unknown displacement components for each layer. A method called single degree of freedom
compensation is adopted to solve the peak value of the capacity curve. The post-peak stage analysis is performed using a forced
iteration approach. The macro-model developed in the study and the complete process analysis methodology are verified by the
experimental and static inelastic analytical results of four RC shear wall specimens.
Supported by: National Natural Science Foundation of China, Grant number 59895410 相似文献