Experimental seismic behavior of squat shear walls with precast concrete hollow moulds

This study proposes an innovative precast shear wall system, called an EVE precast hollow shear wall structure (EVE-PHSW). Precast panels in EVE-PHSW are simultaneously precast with vertical and horizontal holes. Noncontact lap splices of rebars are used in vertical joints connecting adjacent precast panels for automated prefabrication and easy in situ erection. The seismic behavior of EVE walls was examined through a series of tests on six wall specimens with aspect ratios of 1.0∼1.3. Test results showed that EVE wall specimens with inside cast-in situ concrete achieved the desired “strong bending and weak shear” and failed in shear mode. Common main diagonal cracks and brittle shear failure in squat cast-in situ walls were prevented. Inside cast-in situ concrete could significantly improve the shear strength and stiffness of EVE walls. The details of boundary elements (cast-in situ or prefabricated) and vertical joints (contiguous or spaced) had little effect on the global behavior of EVE walls. Noncontact lap splices in vertical joints could enable EVE walls to exhibit stable load-carrying capacity through extensive deformations. Evaluation on design codes revealed that both JGJ 3-2010 and ACI 318-14 provide conservative estimation of shear strength of EVE walls, and EVE walls achieved shear strength reserves comparative to cast-in situ walls. The recommended effective stiffness for cast-in situ walls in ASCE 41–17 appeared to be appropriate for EVE walls.

     

The Reticulatus method for shear strengthening of fair-faced masonry

This paper presents the results of several experimental campaigns recently carried out by the authors and devoted to the investigation of the mechanical performance of wall panels strengthened by applying repointing mortar and high strength stainless steel or composite cords. The reinforcement system, known as Reticulatus, allows the reinforcement of regular and irregular-shape masonry walls, when the fair-faced aspect must be kept. In the perspective of using this reinforcement method, this article summarizes the research that has been done so far, presenting new original test results and discussing the design procedures. Twenty-two square wall panels were loaded in their plane by means of a single point load acting through the panel’s diagonal. Experimental results are presented for four types of cord reinforcement using matched samples, reinforced and not. Increases in shear strength from 15 to 170 % were achieved for the strengthened panels. Each wall panel was loaded well into the lateral post-elastic regime and then unloaded. Experimental results were in good agreement with predictions from simple models which assume the wall panels to behave like a plate, neglecting the contribution of the repointing mortar, and accounting for the non-linear behavior of the masonry.     

Three‐dimensional beam–truss model for reinforced concrete walls and slabs – part 2: modeling approach and validation for slabs and coupled walls

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.     

中空暗缝RC剪力墙板拟静力试验及数值模拟分析

为明晰中空暗缝RC剪力墙抗剪机理和滞回性能,进行1榀1∶3缩尺单层、单跨中空暗缝RC剪力墙板拟静力试验,得到了试件破坏模式、滞回曲线、骨架曲线、刚度退化、强度退化、延性和耗能能力。通过数值模拟分析了混凝土强度、中空暗缝厚度、缝间墙配筋率对剪力墙板水平抗剪承载力的影响。研究结果表明:试件滞回曲线呈捏缩状,耗能能力一般,但具有较好的剪切变形能力;试件最终呈中空暗缝剪碎、缝间墙两端形成弯曲塑性铰的破坏模式;随着混凝土强度的提高和中空暗缝厚度的减小,试件水平抗剪承载力呈增加趋势;缝间墙配筋率对试件水平抗剪承载力及损伤状态的影响较小。     

双向单排配筋混凝土低矮剪力墙抗震性能试验研究

双向单排配筋混凝土低矮剪力墙适用于多层住宅结构。对4个原型的剪跨比为1.0配筋混凝土低矮剪力墙进行了低周反复荷载试验研究,包括1个双向双排配筋混凝土低矮剪力墙和3个双向单排配筋混凝土低矮剪力墙。其中1个双向单排配筋混凝土低矮剪力墙加设暗支撑,用以研究暗支撑对这种新型墙体的作用。在试验研究的基础上,对比分析了各剪力墙的刚度及其衰减过程、承载力、延性、滞回特征、耗能能力及破坏特征。试验表明,经过合理设计,这种双向单排配筋混凝土低矮剪力墙可以满足多层住宅结构抗震要求。     

Strength,stiffness and cyclic deformation capacity of RC frames converted into walls by infilling with RC

In seismic retrofitting of concrete buildings, frame bays are converted into reinforced concrete (RC) walls by infilling the space between the frame members with RC of a thickness of not more than their width. The cyclic behavior of the resulting wall depends on the connection between the RC infill and the surrounding RC members. The paper uses the results from 56 cyclic tests on such composite walls to express their properties in terms of the geometry, the reinforcement and the connection. Properties addressed are: (a) the yield moment at the story base; (b) the secant-to-yield-point stiffness over the shear span of the wall in a story; (c) the deflection at flexural failure in cyclic loading; (d) the cyclic shear resistance, including a sliding shear failure mode. Separate models are given for squat walls failing in shear and for those where the top of the column shears-off. The proposals are modifications of models developed in the past for monolithic RC walls from several hundred cyclic tests; blind application of these latter models as though the walls were monolithic gives, in general, unsafe predictions. By contrast, the diagonal compression strut approach in ASCE41-06 is safe-sided, but gives unacceptably large prediction scatter.     

小剪跨比格构式混凝土墙体抗震性能试验

文章旨在研究不同剪跨比的格构式混凝土墙体抗震性能.将生产车间预制成EPS保温模块拼接成墙体模板,在横向和纵向孔洞中分别布置钢筋,然后在孔内浇筑自密实混凝土,形成“EPS新型节能”格构式混凝土墙体,然后对6个参数不同的试件进行低周反复水平荷载作用的试验.结果,墙体破坏形态为:首先墙体相邻格构柱间的连梁出现环状裂缝和“X”...     

改善混凝土剪力墙抗震性能的研究

混凝土剪力墙被广泛运用于各类结构体系中。它作为主要的抗侧力单元,其刚度大、承载力高,但当剪力墙以受剪破坏为主时,其抗震性能较差。为此,不少学者提出了各种改善混凝土剪力墙抗震性能的措施。本文对几种采用不同构造措施的剪力墙作了简要介绍,特别是介绍一种新型双重组合剪力墙。     

边缘约束构件对钢筋混凝土剪力墙抗震性能的影响

钢筋混凝土剪力墙是高层建筑中的主要抗侧力构件,边缘约束情况是影响剪力墙抗震性能的一个重要因素。为研究边缘约束构件对钢筋混凝土剪力墙抗震性能的影响,本文进行了三片边缘约束情况不同的钢筋混凝土剪力墙的低周反复试验,并对试验结果进行了分析,分析内容包括：破坏形态、水平承载力、位移延性系数、刚度退化、抗震耗能能力等方面。研究结果表明,合理地设置边缘约束能够扩大塑性破坏区域,提高试件的水平承载力,改善其抗震耗能性能。研究进一步发现,边缘纵筋配筋率在提高试件的水平承载力,改善其抗震耗能性能和刚度退化程度方面影响显著,而边缘配箍率对抗震性能的贡献在本次试验分析中表现得并不明显。     

An experimental study of a damage‐controllable plastic‐hinge‐supported wall structure

The reinforced concrete (RC) shear wall serves as one of the most important components sustaining lateral seismic forces. Although they allow advanced seismic performance to be achieved, RC shear walls are rather difficult to repair once the physical plastic hinge at the bottom part has been formed. To overcome this, a damage‐controllable plastic hinge with a large energy dissipation capacity is developed herein, in which the sectional forces are decoupled and sustained separately by different components. The components sustaining the axial and the shear forces all remain elastic even under a rarely occurred earthquake, while the bending components yield and dissipate seismic energy during a design‐level earthquake. This design makes the behavior of the system more predictable and thus more easily customizable to different performance demands. Moreover, the energy dissipation components can be conveniently replaced to fully restore the occupancy function of a building. To examine the seismic behavior of the newly developed component, 3 one third‐scale specimens were tested quasi‐statically, including 1 RC wall complying with the current design codes of China and 2 installed with the damage‐controllable plastic hinges. Each wall was designed to have the same strength. The experimental results demonstrated that the plastic‐hinge‐supported walls had a better energy dissipation capacity and damage controllability than the RC specimen. Both achieved drift ratios greater than 3% under a steadily increasing lateral force.     

高强钢筋混凝土短肢剪力墙抗震性能试验研究

通过对采用高强钢筋的6片T形混凝土短肢剪力墙和采用高强钢筋高强混凝土的6片L形短肢剪力墙进行低周往复加载试验,研究了T形和L形的破坏形态与性能差异,分析了高厚比、轴压比、配箍间距等参数对构件破坏形态、滞回耗能、骨架曲线、延性及耗能等抗震性能的影响,对比分析了构件与普通短肢剪力墙的抗震性能差异。试验结果表明:采用腹板端部箍筋加密的方式可减轻构件端部的损伤和降低正负向加载时承载力和延性的不对称性;T形构件中高厚比为5的试件表现为弯曲破坏,其他构件表现为弯剪破坏;试验中高厚比小的构件相对于高厚比大的试件延性耗能更好,轴压比增大,构件承载力提高但延性降低;与普通短肢剪力墙相比,T形短肢剪力墙承载力和变形能力提高,耗能增加,L形短肢剪力墙承载力提高较大,极限位移增大,构件后期变形能力略有降低,但可以满足抗震性能要求。     

型钢混凝土剪力墙抗震性能影响参数研究

型钢混凝土剪力墙是一种广泛应用于高层混合结构中的剪力墙形式。本文采用通用有限元程序ADINA,以边缘构件含钢率为主要参数,对不同剪跨比的几组剪力墙承载力和变形能力进行了分析,并与考虑了剪力墙混凝土等级、轴压比、配筋率和边缘约束指标等参数影响的剪力墙性能进行了比较研究。结果表明,在高层结构中采用较高强度的混凝土是有利的,但剪力墙的轴压比需要严格限制,且墙体配筋率并不是提高其抗震性能的有效手段。在高层混合结构剪力墙中,通过边缘构件设置型钢可有效增加墙体延性,且边缘约束构件的约束指标可取0.32左右。     

底部开缝预应力剪力墙结构力学性能的有限元分析

根据现浇混凝土结构与装配混凝土结构的耗能特点,建立了底部开缝后张拉预应力摇摆剪力墙结构模型,并采用数值模拟方法研究其抗震耗能性能,分析分布钢筋、预应力水平、轴压力等参数对其力学性能的影响,并与同类型整体现浇剪力墙进行了对比分析。结果表明：底部开缝后张拉预应力摇摆剪力墙结构具有一定的耗能能力,虽然相对于现浇剪力墙结构,其承载力较低,但变形能力较强,墙体损伤和残余变形较小,并且具有较好的自复位能力。     

组合剪力墙的抗震研究与发展

剪力墙是高层建筑结构中的核心抗侧力部件,研制抗震性能好的剪力墙,是建筑抗震设计的关键技术之一。组合剪力墙包括不同材料和不同结构形式的组合,可以发挥不同材料和不同结构形式各自的优势,使剪力墙的延性和耗能能力得以提高,从而改善其抗震性能。本文对国内外一些新型组合剪力墙的抗震研究工作进行了归纳总结,并对其发展作一展望。     

高轴压比下钢桁架-混凝土组合剪力墙抗震研究

轴压比是剪力墙抗震设计中一个重要的控制因素，它直接关系到剪力墙的抗震性能。简要介绍了钢筋混凝土剪力墙和型钢混凝土剪力墙抗震研究的有关成果，重点介绍了轴压比对剪力墙抗震性能的影响。进行了3个1／3缩尺的剪力墙的抗震性能试验研究，包括1个普通混凝土剪力墙、1个内藏钢框架混凝土组合剪力墙和1个内藏钢桁架混凝土组合剪力墙。试验表明：在高轴压比情况下，内藏钢框架、内藏钢桁架混凝土组合剪力墙的抗震性能比普通混凝土剪力墙明显提高。     

轴压比对中等高度LC结构剪力墙抗震性能的影响

轻骨料混凝土(L ight-we ight concrete,简称LC)剪力墙的轴压比是剪力墙抗震设计时一个重要的控制因素,直接关系到其延性性能。为使设计规程具有足够的理论依据,本文通过对六榀轻骨料混凝土剪力墙试件的试验,研究了在低周反复荷载作用下,着重考虑不同轴压比对中等高度有边框剪力墙的破坏形态和变形性能的影响效应,对其滞回特性进行分析,计算了各剪力墙的刚度退化率与延性系数,并将无竖缝剪力墙与带竖缝剪力墙的抗震性能进行了对比。     

预制装配式剪力墙结构墙板节点抗震性能研究

为掌握预制装配式剪力墙结构墙板节点的抗震性能,对2个现浇试件和2个预制装配式试件进行了拟静力试验.结合非线性分析手段,从承载能力、变形能力、受力机理以及破坏模式等方面综合分析了其抗震性能,并初步探讨了墙板连接钢筋的合理直径.分析结果表明:与现浇试件相比,预制装配式试件承载能力较高,位移延性系数相同,滞同环均较饱满,具有...     

基于性能的抗震设计方法在剪力墙结构中的应用

本文对基于性能的抗震设计方法中最具有代表性的直接基于位移的设计方法在剪力墙结构中的应用进行了研究。采用结构非线性分析程序探讨了墙厚、混凝土强度等级、纵筋配筋率、钢筋级别、轴压比、墙长等因素对单肢剪力墙屈服位移的影响,从而对现有的屈服曲率计算公式进行了改进。另外将按顶点荷载作用下的屈服位移计算公式求出的屈服位移与实际倒三角形荷载作用下的剪力墙屈服位移进行了比较,,从而推导出倒三角形荷载作用下的屈服位移计算公式。     

轻钢骨混凝土剪力墙延性的非线性有限元分析

轻钢骨混凝土剪力墙结构作为新型结构在工程界要得到认同并推广使用,必须对该结构的各项性能指标进行系统的试验研究和理论分析。本文应用ADINA有限元软件对轻钢骨混凝土剪力墙延性进行非线性有限元分析,根据不同的高宽比、轴压比、轻钢骨配筋率以及端部配筋模型的计算结果,对该结构体系的延性及其破坏形态进行综合分析,并对轻钢骨混凝土剪力墙轴压比设计提出建议。分析结果表明,高宽比主要控制轻钢骨混凝土剪力墙的破坏形态,轴压比对其结构的延性的影响最为显著,而端部配筋对其延性影响不大。     

Experimental research on the seismic behavior of CSPSWs connected to frame beams

The seismic performance of composite steel plate shear walls (CSPSWs) that consist of a steel plate shear wall (SPSW) with reinforced concrete (RC) panels attached to one or both sides by means of bolts or connectors is experimentally studied. The shear wall is connected to the frame beams but not to the columns. This arrangement restrains the possible out-of-plane buckling of the thin-walled steel plate, thus significantly increasing the bearing capacity and ductility of the overall wall, and prevents the premature overall or local buckling failure of the frame columns. From a practical viewpoint, these solutions can provide open space in a floor as this type of composite shear walls with a relatively small aspect ratio can be placed parallel along a bay. In this study, four CSPSWs and one SPSW were tested and the results showed that both CSPSWs and SPSW possessed good ductility. For SPSW alone, the buckling appeared and resulted in a decrease of bearing capacity and energy dissipation capacity. In addition, welding stiffeners at corners were shown to be an effective way to increase the energy dissipation capacity of CSPSWs.