配筋砌块砌体短肢剪力墙恢复力模型

通过18片足尺全灌芯配筋砌块砌体短肢剪力墙低周往复荷载试验,研究了在压弯剪复合受力下墙体的抗震性能、刚度衰减方程以及恢复力模型。选取截面厚度包含190、240 mm和290 mm共3种块型的墙体,基于试验得到墙体骨架曲线,并计算得到归一化骨架曲线,简化为带下降段的三折线模型。通过计算得到模型中各阶段刚度比,用于确定骨架曲线的特征点。针对各次试验的刚度进行回归分析,得到满足指数衰减规律的刚度方程,据此提出了一种适用于配筋砌块砌体短肢剪力墙的滞回规则,并根据骨架曲线的各特征点,模拟了各次试验的滞回曲线。研究结果表明:模拟曲线能较好地反映配筋砌块砌体短肢剪力墙的"捏拢"现象,此恢复力模型可用于地震作用下配筋砌块砌体短肢剪力墙的非线性动力反应分析。     

配筋砌块砌体短肢剪力墙恢复力模型

通过18片足尺全灌芯配筋砌块砌体短肢剪力墙低周往复荷载试验,研究了在压弯剪复合受力下墙体的抗震性能、刚度衰减方程以及恢复力模型。选取截面厚度包含190、240 mm和290 mm共3种块型的墙体,基于试验得到墙体骨架曲线,并计算得到归一化骨架曲线,简化为带下降段的三折线模型。通过计算得到模型中各阶段刚度比,用于确定骨架曲线的特征点。针对各次试验的刚度进行回归分析,得到满足指数衰减规律的刚度方程,据此提出了一种适用于配筋砌块砌体短肢剪力墙的滞回规则,并根据骨架曲线的各特征点,模拟了各次试验的滞回曲线。研究结果表明：模拟曲线能较好地反映配筋砌块砌体短肢剪力墙的“捏拢”现象,此恢复力模型可用于地震作用下配筋砌块砌体短肢剪力墙的非线性动力反应分析。     

配筋砌块砌体剪力墙抗剪性非线性分析

本文采用ANSYS软件对 7片纵横配筋大剪跨比的砌块砌体剪力墙进行数值模拟 ,得出承载力计算值与试验值相吻合 ,侧移计算值略小于试验值的结论 ;并认为将ANSYS软件用于砌块剪力墙的非线性有限元分析是一种可行的研究手段     

配筋混凝土砌块砌体剪力墙位移延性的数值分析

针对设计规范计算方法的不足,探讨了数值计算方法在配筋混凝土砌块砌体剪力墙位移延性计算中的应用问题,给出了详细的计算步骤,并编写程序进行了配筋混凝土砌块砌体剪力墙位移延性系数计算.研究结果表明,采用数值计算方法,能较好地解决配筋混凝土砌块砌体剪力墙延性简化计算存在的问题,其适应性更强,便于工程应用.     

配筋砌块砌体剪力墙结构设计注意事项分析

对配筋砌块砌体剪力墙结构进行了简单介绍,分析了配筋砌块砌体剪力墙在国外的基本应用情况及设计中需要注意的两个关键问题,对实际工程设计具有一定的参考价值。     

混凝土砌块配筋砌体剪力墙的曲率和曲率延性分析

通过对混凝土砌块配筋砌体剪力墙结构的曲率和曲率延性进行演算和说明,推导曲率延性与轴压比的关系,并举有例题,能清楚看出轴压比和配筋量对砌体延性的影响.     

配筋砌块砌体剪力墙配筋方法的商讨

配筋砌块砌体剪力墙抗弯钢筋的配筋方法是一个很值得商讨的问题。多数人认为配筋应配在剪力墙的端部,因此在“设计规范”和“规程”中都规定:在剪力墙的端部要做边缘构件(暗柱),在剪力墙的转角处、丁字头交接处、十字交叉处等部位要配筋。这些观点只在构件的弹性受力阶段才是正确的。在抗震设计中,在地震的作用下构件已进入弹塑性阶段或塑性阶段,如按上述方式配筋是有害的。本文将对此提出笔者的观点。     

配筋砌块砌体剪力墙的研究和应用

分析了配筋砌块砌体剪力墙的受力特性和破坏机理 ,论述了这种结构的应用和研究情况 ,提出了我国配筋砌块砌体剪力墙结构应用和研究中存在和应解决的问题     

配筋砌块砌体剪力墙结构示范工程株洲国脉家园住宅小区

本文通过介绍湖南省乃至中南地区首个配筋砌块砌体剪力墙体系示范工程——株洲国脉家园住宅小区．总结出配筋砌块砌体剪力墙结构体系的施工要点及优势。     

高层配筋砌块砌体剪力墙的延性设计研究

针对配筋砌块砌体的特点,采用数值计算的方法确定配筋砌块砌体剪力墙的屈服曲率和极限曲率,并建立剪力墙曲率延性比和位移延性比的关系。根据计算结果,讨论轴压比、剪跨比、边缘钢筋屈服强度、腹板竖向钢筋的抗力、砌体的抗压强度和极限压应变对剪力墙位移延性的影响,其中限制轴压比、设置约束边缘构件是提高剪力墙延性的有效途径。通过推导出的轴压比限值的近似公式,分析各因素对轴压比限值的影响,并建议采用约束砌块砌体和约束混凝土作为约束边缘构件以提高墙的延性。结合高层建筑工程实际,分析确定不同约束边缘构件的矩形截面和工字形截面剪力墙的轴压比限值,提出约束边缘构件的构造要求和实用的设计建议。     

Finite element modelling of deformation characteristics of historical stone masonry shear walls

Two dimensional nonlinear finite element analysis based on experimental test data has been carried out to model deformation characteristics, such as load–displacement envelope diagrams and failure modes of historical stone masonry shear walls subjected to combined axial compression and lateral shear loading. An experimental research work was carried out on three different types of historical stone masonry shear walls that can be considered representative of ancient stone masonry constructions. Those three types of masonry are: (i) sawn dry-stack or dry-stone masonry without bonding mortar, (ii) irregular stone masonry with bonding mortar, and (iii) rubble masonry with irregular bonding mortar thickness. Plasticity theory based micro modelling techniques has been used to carry out the analysis. The stone units were modelled using eight node continuum plane stress elements with full Gauss integration. The joints and unit-joint interfaces were modelled using a six node zero thickness line interface elements with Lobatto integration. This paper outlines the experimental research work, details of numerical modelling carried out and report the numerical lateral load–displacement diagrams and failure modes. The numerical analysis results were compared with the experimental test results and good agreement was found.     

Nonlinear static finite element analysis of reinforced masonry walls in tall buildings

A finite element computer program or code, FEM/I, has been developed for the nonlinear, static analysis of reinforced masonry building components subjected to in-plane loading. The masonry is represented by a material with bimodular orthotropy, and includes tension stiffening, compression softening, and strain softening, as well as a degrading unloading rule. The masonry model incorporates a tension crack orientation adjustment approach, where the orientation of the final cracks can be different from the initial cracks. The model also includes a compressive strength reduction after tensile cracking normal to the principal compressive strains. Additionally, the model includes a compressive strength increase due to lateral compressive confinement. The reinforcement is represented by an orthotropic material with a bilinear stress-strain relationship and includes unloading. The FEM/I code is operational on IBM compatible personal computers, such as the 286/386/486 systems. This capability makes the developed technology available to a large group of engineers and researchers, since a large main frame computer is not required to operate the program. The computer program is expected to be particularly useful to designers of tall reinforced masonry buildings that contain components with unusual configurations. These components can be analyzed to properly assess their structural performance.     

预制圆孔板剪力墙非线性有限元分析

采用ANSYS有限元软件,对一个设置现浇边缘构件的单片预制圆孔板剪力墙试件进行了在定轴压力和单调递增水平力作用下的非线性分析,与拟静力试验结果进行了比较,两者符合较好,验证了计算模型和参数取值的合理性。在此基础上,对四个设置现浇边缘构件的单片及双片预制圆孔板剪力墙试件进行了非线性有限元分析。结果表明,无论是按弯曲破坏还是按剪切破坏设计的试件,都是墙底截面开裂,边缘构件沿高度出现水平裂缝,圆孔板剪力墙以斜裂缝为主,斜裂缝数量多,布满整个墙面,没有出现集中的塑性铰,有利于抗震耗能;双片墙试件的开裂荷载和最大荷载显著高于单片墙试件的。结论可为预制圆孔板剪力墙这种新型装配整体式住宅建筑体系的推广应用提供理论依据。     

Investigation of current seismic design provisions for reinforced masonry shear walls

Current seismic design provisions were investigated to determine if optimum designs resulted from their use. Forty-two components of recorded ground motions were used for the investigation. These ground motions were recorded in the Imperial Valley in 1940 and 1979. These ground motions were assumed to contain a consistent value of soils factor. The tabulation of the Imperial Valley ground motion revealed that these motions had mean velocity-acceleration ratios and velocity and acceleration amplification factors that exceeded those determined by prior studies. The investigation confirmed that a modified seismic design formula provided a more consistent dynamic behavior for reinforced masonry shear walls. The investigation also studied the influence of reinforcement ratios of masonry shear walls, the influence of under and excess strength, and the effectiveness of stiffness modification in lieu of strength modification. The investigations supported the conclusions that limitation of the vertical reinforcement ratio increases the displacement ductility of reinforced masonry shear walls, that the current NEHRP Recommended Provisions require a near optimum required strength, and that modification of the stiffness of the shear wall, in lieu of strength modification, is highly beneficial in limiting nonlinear displacements of reinforced masonry shear walls.     

Finite element analysis of shear deformation in reinforced concrete shear-critical beams

The objective of this paper was to study the contribution of shear deformation in reinforced concrete (RC) shear-critical beams. A 2D concrete material model based on smeared fixed crack was presented and incorporated into a commercial finite element (FE) software. A method of calculating shear and flexure deformation separately out of total deformation in the shear span was presented and implemented into the FE analysis. Several experiments of RC shear-critical beams were simulated and good agreement between the experimental and numerical results was obtained in terms of total deformation, flexure deformation, shear deformation and crack patterns. The results show that after shear cracking, the contribution of shear deformation to total deformation increases rapidly. The shear span-to-depth ratio, the longitudinal reinforcement, the shear reinforcement and the load level could be the critical factor to influence the contribution of shear deformation. It appears that for RC shear-critical beams without shear reinforcement, the deformational behaviour is governed by flexure deformation. However, for RC beams with shear reinforcement, the contribution of shear deformation is not negligible after shear cracks develop. Moreover, the measuring method could also affect the measured shear deformation. Finally, future work on experimental investigation into this topic is recommended.     

钢筋混凝土无洞叠合墙体非线性有限元分析

在试验研究的基础上,运用有限元分析程序ANSYS对钢筋混凝土无洞叠合墙体进行非线性分析。通过建立合理的力学模型,模拟分析了叠合墙体的裂缝开展与分布、承载能力、破坏模式等方面的特点和规律,并与试验结果进行对比验证。有限元值与试验值吻合较好,说明本研究在进行有限元分析时所选择的计算模型、材料本构关系、破坏准则等较为合理的,可以应用于叠合剪力墙的进一步分析研究,弥补试验研究的局限性。剪式支架能使钢筋混凝土叠合剪力墙的预制部分与现浇混凝土形成整体,共同工作,承受外部荷载。     

Prediction of the shear strength of reinforced masonry walls using a large experimental database and artificial neural networks

This paper analyses the accuracy of a selection of expressions currently available to estimate the in-plane shear strength of reinforced masonry (RM) walls, including those presented in some international masonry codes. For this purpose, predictions of such expressions are compared with a set of experimental results reported in the literature. The experimental database includes specimens built with ceramic bricks and concrete blocks tested in partially and fully grouted conditions, which typically present a shear failure mode. Based on the experimental data collected and using artificial neural networks (ANN), this paper presents alternative expressions to the different existing methods to predict the in-plane shear strength of RM walls. The wall aspect ratio, the axial pre-compression level on the wall, the compressive strength of masonry, as well as the amount and spacing of vertical and horizontal reinforcement throughout the wall are taken into consideration as the input parameters for the proposed expressions. The results obtained show that ANN-based proposals give good predictions and in general fit the experimental results better than other calculation methods.