Topology optimization of shear wall structures under seismic loading

A topology optimization formulation is developed to find the stiffest structure with desirable material distribution subjected to seismic loads. Finite element models of the structures are generated and the optimality criteria method is modified using a simple penalty approach and introducing fictitious strain energy to simultaneously consider both material volume and displacement constraints. Different types of shear walls with/without opening are investigated. Additionally, the effects of shear wall-frame interaction for single and coupled shear walls are studied. Gravity and seismic loads are applied to the shear walls so that the definitions provide a practical approach for locating the critical parts of these structures. The results suggest new viewpoints for architectural and structural engineering for placement of openings.

Experimental and analytical study on seismic behavior of steel-concrete multienergy dissipation composite shear walls

In this paper, a steel-concrete multi-energy dissipation composite shear wall, comprised of steel-reinforced concrete （SRC） columns, steel plate （SP） deep beams, a concrete wall and energy dissipation strips, is proposed. In order to study the multi-energy dissipation behavior and restorability after an earthquake, two stages of low cyclic loading tests were carded out on ten test specimens. In the first stage, test on five specimens with different number of SP deep beams was carried out, and the test lasted until the displacement drift reached 2%. In the second stage, thin SPs were welded to both sides of the five specimens tested in the first stage, and the same test was carried out on the repaired specimens （designated as new specimens）. The load-bearing capacity, stiffness, ductility, hysteretic behavior and failure characteristics were analyzed for both stages and the results are discussed herein. Extrapolating from these results, strength calculation models and formulas are proposed herein and simulations using ABAQUS carried out, they show good agreement with the test results. The study demonstrates that SRC columns, SP deep beams, concrete wall and energy dissipation strips cooperate well and play an important role in energy dissipation. In addition, this study shows that the shear wall has good recoverability after an earthquake, and that the welding of thin SP＇s to repair a deformed wall is a practicable technique.

Seismic behavior and mechanism analysis of innovative precast shear wall involving vertical joints

To study the seismic performance and load-transferring mechanism of an innovative precast shear wall(IPSW) involving vertical joints, an experimental investigation and theoretical analysis were successively conducted on two test walls. The test results confirm the feasibility of the novel joints as well as the favorable seismic performance of the walls, even though certain optimization measures should be taken to improve the ductility. The load-transferring mechanism subsequently is theoretically investigated based on the experimental study. The theoretical results show the load-transferring route of the novel joints is concise and definite. During the elastic stage, the vertical shear stress in the connecting steel frame(CSF) distributes uniformly; and each high-strength bolt(HSB)primarily delivers vertical shear force. However, the stress in the CSF redistributes when the walls develop into the elastic-plastic stage. At the ultimate state, the vertical shear stress and horizontal normal stress in the CSF distribute linearly; and the HSBs at both ends of the CSF transfer the maximum shear forces.

Analysis and seismic tests of composite shear walls with CFST columns and steel plate deep beams

A composite shear wall concept based on concrete filled steel tube （CFST） columns and steel plate （SP） deep beams is proposed and examined in this study. The new wall is composed of three different energy dissipation elements： CFST columns; SP deep beams; and reinforced concrete （RC） strips. The RC strips are intended to allow the core structural elements - the CFST columns and SP deep beams - to work as a single structure to consume energy. Six specimens of different configurations were tested under cyclic loading. The resulting data are analyzed herein. In addition, numerical simulations of the stress and damage processes for each specimen were carried out, and simulations were completed for a range of location and span-height ratio variations for the SP beams. The simulations show good agreement with the test results. The core structure exhibits a ductile yielding mechanism characteristic of strong column-weak beam structures, hysteretic curves are plump and the composite shear wall exhibits several seismic defense lines. The deformation of the shear wall specimens with encased CFST column and SP deep beam design appears to be closer to that of entire shear walls. Establishing optimal design parameters for the configuration of SP deep beams is pivotal to the best seismic behavior of the wall. The new composite shear wall is therefore suitable for use in the seismic design of building structures.

Nonlinear earthquake response analysis and energy calculation for seismic slit shear wall structures

Based on the concept of structural passive control,a new type of slit shear wall,with improved seismic performance when compared to an ordinary solid shear wall,was proposed by the authors in 1996.The idea has been verified by a series of pseudo-static and dynamic tests.In this paper a macro numerical model is developed for the wall element and the energy dissipation device.Then,nonlinear time history analysis is carried out for a 10-story slit shear wall model tested on a shaking table.Furthermore,the seismic input energy and the individual energy dissipated by the components are calculated by a method based on Newmark-β assumptions for this shear wall model,and the advantages of this shear wall are further demonstrated by the calculation results from the viewpoint of energy.Finally,according to the seismic damage criterion on the basis of plastic accumulative energy and maximum response,the optimal analysis is carried out to select design parameters for the energy dissipation device.

Seismic Analysis of Shear-Wall Structures with Vertically Installed Dampers

Shear-wall structures are quite common in seismic areas because of their successful seismic behavior during severe earthquakes. But shear walls are prone to brittle failure. This study proposes a new method of vertically installed dampers （VID） to reduce the vibration in shear-wall structures. The motion characteristic of a vertical damping system is that every mass has horizontal and rotational displacements simultaneously, The establishment of dynamic equations should take into account the equilibrium conditions of both horizontal and rotational vibrations. Dynamic equilibrium equations of VID systems are derived from a model of a structure with VID. An example shear-wall structure, with and with- out VID, is studied. There are some changes in the characteristics of the maximum horizontal displacement response. Without dampers, the relative displacements between different floors in the shear wall increase with height. With dampers, the relative displacements are more uniformly distributed, and lateral displacements at the top and at the bottom are closer. When the damping coefficient is 1 000 kN · s/ m, the numerical results reveal that the maximum horizontal displacement and the maximum rotational displacement of the top floor have reduced by 59.3 % and 54.8 % respectively.

Study on the Distribution Law of Horizontal Seismic Forces between Slab-Column and Shear Wall

In slab column-shear wall structures,both the whole structure′s seismic behavior and failure mode are greatly influenced by the distribution of horizontal seismic forces between slab-column and shear wall.In this paper,a pushover analysis of topical slab column-shear wall structure was carried out,the seismic shear force that the slab-column and shear wall should undertake was worked out,the influences of plastic internal force redistribution and structure stiffness characteristic value on horizontal seismic distribution were studied and the calculation formula was given.The analysis results showed that with the yield of the shear walls,the story shear force was undertaken by slab-columns correspondingly increased while with the decrease of characteristic value of stiffness of a structure,and the horizontal seismic force was undertaken by slab-columns correspondingly decreased.According to the code,the design of horizontal force distribution may be cause insecurity problems,so it is necessary to give the distribution law of horizontal seismic forces in slab-column shear wall structures as the supplement to the corresponding regulation of the Code.

Seismic performance evaluation of steel frame-steel plate shear walls system based on the capacity spectrum method

This paper presents some methods that the standard acceleration design response spectra derived from the present China code for seismic design of buildings are transformed into the seismic demand spectra, and that the base shear force-roof displacement curve of structure is converted to the capacity spectrum of an equivalent single-degree-of-freedom (SDOF) system. The capacity spectrum method (CSM) is programmed by means of MATLAB7.0 computer language. A dual lateral force resisting system of 10-story steel frame-steel plate shear walls (SPSW) is designed according to the corresponding China design codes. The base shear force-roof displacement curve of structure subjected to the monotonic increasing lateral inverse triangular load is obtained by applying the equivalent strip model to stimulate SPSW and by using the finite element analysis software SAP2000 to make Pushover analysis. The seismic performance of this dual system subjected to three different conditions, i.e. the 8-intensity frequently occurred earthquake, fortification earthquake and seldom occurred earthquake, is evaluated by CSM program. The excessive safety of steel frame-SPSW system designed according to the present China design codes is pointed out and a new design method is suggested.

Post-fire cyclic behavior of reinforced concrete shear walls

The effects of fire exposure,reinforcement ratio and the presence of axial load under fire on the seismic behavior of reinforced concrete(RC) shear walls were investigated.Five RC shear walls were tested under low cyclic loading.Prior to the cyclic test,three specimens were exposed to fire and two of them were also subjected to a constant axial load.Test results indicate that the ultimate load of the specimen with lower reinforcement ratio is reduced by 15.8%after exposure to elevated temperatures.While the reductions in the energy dissipation and initial stiffness are 59.2%and 51.8%,respectively,which are much higher than those in the ultimate load.However,this deterioration can be slowed down by properly increasing reinforcement due to the strength and stiffness recovery of steel bars after cooling.In addition,the combined action of elevated temperatures and axial load results in more energy dissipation than the action of fire exposure alone.

Experimental study on the seismic performance of new sandwich masonry walls

Sandwich masonry walls are widely used as energy-saving panels since the interlayer between the outer leaves can act as an insulation layer.New types of sandwich walls are continually being introduced in research and applications,and due to their unique bond patterns,experimental studies have been performed to investigate their mechanical properties,especially with regard to their seismic performance.In this study,three new types of sandwich masonry wall have been designed,and cyclic lateral loading tests were carried out on five specimens.The results showed that the specimens failed mainly due to slippage along the bottom cracks or the development of diagonal cracks,and the failure patterns were considerably influenced by the aspect ratio.Analysis was undertaken on the seismic response of the new walls,which included ductility,stiffness degradation and energy dissipation capacity,and no obvious difference was observed between the seismic performance of the new walls and traditional walls.Comparisons were made between the experimental results and the calculated results of the shear capacity.It is concluded that the formulas in the two Chinese codes（GB 50011 and GB 50003） are suitable for the calculation of the shear capacity for the new types of walls,and the formula in GB 50011 tends to be more conservative.

Improvement of Concrete Shear Wall Structures by Smart Materials

Smart materials have found numerous applications in many areas in civil engineering recently. One class of these materials is shape memory alloy (SMA) which exhibits several unique characteristics such as superelasticity and shape memory effect. Due to these characteristics, research efforts have been extended to use SMA in controlling civil structures. This paper investigates the effectiveness of SMA reinforcements in enhancing the behavior of shear walls, especially when subjected to seismic excitations. Two ordinary and coupled shear walls were introduced as reference structures and were modeled by ABAQUS software. For improving the seismic response of the shear walls, vertical SMA reinforcing bars were proposed to be implemented like conventional steel reinforcements, throughout the height of the structures and in every connecting beam in the coupled shear wall system. The one dimensional superelastic model of SMA material was implemented in the computer software using FORTRAN code. The dynamic response of the shear walls subjected to seismic loading was investigated through time history analyses under El-centro and Koyna records. The results showed that using superelastic SMA material instead of steel bars caused remarkable reduction in residual displacement for both ordinary and coupled shear walls. In addition, SMA reinforcements could significantly decrease the maximum deflection of the coupled shear wall system.

焊接多腔双钢板-混凝土组合剪力墙抗震性能分析

大多数双钢板-混凝土组合剪力墙采用螺栓连接或焊接肋的方式使钢板和混凝土协同工作。然而,这种连接方式可能导致整体性和塑性变形效率较低,且制作复杂,焊接多腔双钢板-混凝土组合剪力墙能够有效地避免这些问题。为了深入研究焊接多腔双钢板-混凝土组合剪力墙的抗震性能,基于约束混凝土真三轴塑性-损伤本构模型和钢材弹塑性混合强化-韧性损伤本构模型,建立了组合剪力墙的精细化三维实体-壳模型,将模拟所得的滞回曲线、骨架曲线、刚度退化曲线、弹性刚度、承载力、累积耗能、等效阻尼粘滞系数和延性系数与已有拟静力试验结果相比较,发现两者吻合较好。分析结果表明:轴压比对组合剪力墙模型算例刚度和承载力的影响较小,而随剪跨比增大,组合剪力墙模型算例的刚度和承载力呈线性降低;轴压比对组合剪力墙模型算例总塑性耗能的影响较小,而剪跨比的影响较大,剪力墙总塑性耗能随剪跨比增大而降低;轴压比和剪跨比都不会改变算例各部件的耗能分配机制,即组合剪力墙模型算例以外钢板和内隔板耗能为主。

装配式混凝土剪力墙结构接缝连接研究进展

装配式剪力墙结构拼装时存在大量的水平接缝和竖向接缝,由于剪力墙的刚度较大,接缝连接处易存在刚度不足引起的损伤集聚问题,成为影响结构整体性和抗震性能的决定性因素。总结了国内外正在发展的预制装配式剪力墙结构水平和竖向接缝的连接形式,并对各类连接形式的构造特点、抗震性能、应用优势和技术瓶颈进行了系统阐述和分析,在此基础上探讨了装配式剪力墙结构接缝连接技术的发展方向。结果表明:目前湿式连接技术已较为成熟且被广泛应用,但仍存在现场湿作业量大、质量不易检测和控制等问题;干式连接技术工业化程度高,但对施工精度的要求也高,可能产生的螺栓松动、锈蚀以及磨损问题限制了其工程应用;将消能减震技术融入竖向接缝连接,利用超高性能混凝土实现水平接缝连接,并结合可恢复功能防震技术,是未来装配式剪力墙结构高质量发展的新增长点。

水平双轴加载下带翼缘RC 剪力墙抗震性能试验研究

为了揭示双轴耦合效应对不同截面形式带翼缘RC剪力墙多维抗震性能的影响,对3个T形截面和2个L形截面RC剪力墙分别沿其主轴方向进行了低周往复加载试验,对比分析了水平单、双轴加载下带翼缘RC剪力墙的破坏特征、滞回特性、承载力、延性、极限位移角、耗能能力与钢筋应变。研究表明:T形墙和L形墙的破坏均呈现出明显的非对称性,即破坏集中于墙肢自由端,双轴加载加重了带翼缘RC剪力墙的开裂和损伤程度,且易引起剪力墙局部损伤集中;与单轴加载相比,双轴加载不仅削弱了带翼缘RC剪力墙各受力方向的承载力与变形能力、增大了腹板塑性铰区弯曲变形在总变形中的占比、加速了耗能进程、降低了单个方向的耗能能力,并且增大了腹板与翼缘竖向钢筋的应变以及翼缘的剪力滞后效应;双轴耦合效应对L形墙损伤的影响较T形墙更为显著,并导致双轴加载下L形墙各抗震性能指标的衰减程度大于T形墙。考虑双轴受力后,中国抗震规范关于RC剪力墙层间位移角的限值仍较为安全,但安全冗余度降低。

装配式轻钢框架-轻钢骨架轻混凝土墙板结构抗震性能

为研究装配式轻钢框架-轻钢骨架轻混凝土墙板结构抗震性能,对1个足尺轻钢框架结构试件和3个足尺轻钢框架-轻钢骨架轻混凝土墙板结构试件进行了低周反复荷载下的抗震性能试验及理论分析,试件变量包括:2种装配构造,即内嵌式装配墙板、外贴式装配墙板;2种轻钢骨架轻混凝土墙板,即框架式轻钢骨架轻混凝土墙板、桁架式轻钢骨架轻混凝土墙板。研究了各试件的破坏特征和损伤演化过程,分析了结构滞回特性、承载力、变形能力、刚度退化、耗能性能和应变。结果表明:装配式轻钢框架-轻钢骨架轻混凝土墙板结构共同工作性能良好,其水平承载力相比轻钢框架提高了204.7%~210.4%,抗侧刚度提高了257.3%~512.5%,结构变形及耗能能力有显著提高;内嵌墙板的自攻钉连接构造以及外贴墙板的螺栓连接构造传力性能可靠,结构具备2道抗震防线的受力特征;基于简化塑性分析模型以及拉压杆软化桁架模型,对试件承载力进行了计算,计算结果与试验符合较好。

HPC端部加强双钢板组合剪力墙的抗震性能

为研究高性能混凝土端部加强双钢板组合剪力墙受力机理及破坏形态,以轴压比、腹部普通混凝土强度等级为关键参数,设计了4片普通试件,7片HPC端部加强试件,运用ABAQUS构建其有限元模型,研究其抗震性能。结果表明:同轴压比下,HPC端部加强试件相比普通试件屈服荷载提高16.30%,峰值荷载提升13.40%;随着轴压比提高,HPC端部加强试件峰值荷载和屈服荷载分别提高7.22%和2.72%,随着轴压比减小,HPC端部加强试件延性提升22.26%;提高腹部腔体混凝土强度等级,HPC端部加强试件的屈服荷载和峰值荷载分别提高13.01%和11.14%,延性提升16.91%。

可恢复功能装配式高强再生混凝土剪力墙抗震性能试验研究

为推动高强再生混凝土构件应用于可恢复功能建筑结构,提出一种边缘构件配置弱粘结超高强纵筋的装配式高强再生混凝土剪力墙。对4个剪跨比为2.2的装配式高强再生混凝土剪力墙进行低周反复荷载试验,分析了边缘配置弱粘结超高强纵筋、墙体有无钢纤维的装配式高强再生混凝土剪力墙的损伤破坏形态、滞回性能、刚度退化、残余变形、裂缝宽度等抗震与可恢复性能指标。结果表明:在大变形条件下,边缘配置弱粘结超高强纵筋的装配式高强再生混凝土剪力墙水平承载力持续增大,混凝土损伤程度较轻,抗侧刚度退化缓慢,残余变形与裂缝宽度较小。基于试验结果,建议了可恢复功能装配式高强再生混凝土剪力墙在1%位移角下的抗震承载力计算方法,其计算结果与试验结果符合较好。

联肢弯剪型钢板剪力墙抗震性能试验研究

联肢钢板剪力墙结构是将2片钢板剪力墙通过钢连梁连接形成的抗侧力结构。通过对1榀1/3缩尺的4层联肢弯剪型钢板剪力墙试件进行低周往复加载试验,从滞回曲线、骨架曲线、延性、承载力及刚度退化、耗能能力等方面研究了该结构体系的抗震性能,并且对试件的屈服顺序和变形模式进行了分析。结果表明:联肢钢板剪力墙试件的延性系数达到5.03,承载力退化系数均大于0.96,承载力和刚度退化稳定,等效黏滞阻尼系数达到0.25以上,表明联肢弯剪型钢板剪力墙具有优越的抗震性能。加载过程中,连梁先于墙板发生屈服,墙板先屈曲后屈服,此后柱脚和横梁相继屈服。连梁的引入改变了结构的屈服机制,提高了整体的延性和耗能能力,能够组成多道抗震防线,且试件整体最终也体现出合理的破坏机制。整体侧移曲线呈弯剪变形模式。该试验研究更加贴合实际工程中联肢钢板剪力墙结构的应用情况,为联肢钢板剪力墙结构的进一步研究和应用提供了试验基础。

考虑楼板作用的双面叠合剪力墙有限元分析

为了保证双面叠合剪力墙结构体系应用的安全性和可靠性,建立由上、下两层墙体和中间楼板组成的双面叠合剪力墙构件模型及现浇对比模型,并进行基于Abaqus软件的数值模拟分析。研究内容包括双面叠合剪力墙整体位移、混凝土及钢筋的应力分布、最大承载力、耗能能力。结果表明,在小震弹性阶段,带楼板的双面叠合墙板与现浇对比试件的刚度一致;在大震作用下,带楼板的双面叠合墙板的耗能能力低于现浇对比试件,但总体耗能能力都较好。因此,合理设计下的双面叠合剪力墙结构具有良好的抗震性能。

自攻钉集块连接混凝土复合剪力墙抗震性能试验

提出了适用于装配式混凝土复合剪力墙结构的自攻钉集块连接构造,为研究自攻钉集块连接混凝土复合剪力墙的抗震性能,设计制作了3个剪跨比为1.39的足尺剪力墙试件,进行了低周反复荷载试验,主要变量包括自攻钉集块连接构造、自攻钉集块与后浇条带组合连接构造以及L形边框构造柱。分析了试件破坏模式、承载力、滞回特性、刚度及退化、变形能力、耗能性能和应变特征等。结果表明:自攻钉集块连接构造装配便捷,受力性能可靠;采用自攻钉集块与后浇条带组合连接构造试件的承载力及刚度相比自攻钉集块连接构造分别提高了8.54%和6.03%;设置L形边框构造柱的试件承载力、刚度及耗能分别提高了67.48%、129.33%和277.93%。自攻钉集块连接复合剪力墙具有良好的抗震性能,满足装配式低层住宅混凝土复合剪力墙结构的抗震设计要求,可用于实际工程。