Behaviour of cold-formed steel shear wall panels under monotonic and reversed cyclic loading

This paper presents the results of an experimental study on the behaviour and strength of the cold-formed steel shear wall panel (CFSSWP) with calcium silicate board as sheathing, when subjected to monotonically increasing and reversed cyclic in-plane shear deformation. These specimens were specifically designed to reach the strength as governed by the strength of the screw connection between the board and the CFS framing and avoid all other modes of failure, ahead of this. The main objectives of the experimental study are (a) to study the influence of board thicknesses and the distance of the screws from the nearest free edge of the board on the wall panel behaviour and strength; (b) to study the behaviour of different wall board configurations normally used in construction practice (c) to develop the values of the important parameters that determine the load-deformation behaviour of the wall panels under in-plane shear and (d) to determine the different limit states in the failure of the screws connecting the board and the CFS framing in such CFSSWP. In addition, a simplified design equation is proposed to evaluate the ultimate shear strength of CFSSWP based on the strength of the screw connection obtained from a sub assemblage shear strength test.     

冷成型钢龙骨-覆面板材自攻螺钉连接力学性能试验研究

冷成型钢复合剪力墙是冷成型钢结构体系的主要抗侧构件,其受力性能与轻钢骨架-覆面板材自攻螺钉连接的受剪性能密切相关。对36组冷成型钢龙骨-波特板自攻螺钉连接进行抗剪试验,分析了板材类型、螺钉边距和螺钉数量等因素对其受力性能的影响。研究结果表明：自攻螺钉连接件单向受拉时均发生了板材的脆性破坏,而单向受压时连接件破坏呈延性;板材类型、螺钉数量和加载方式对连接件的峰值荷载具有显著影响,中密度波特板连接件的峰值荷载比低密度波特板连接件的峰值荷载高48%～95%,单根自攻螺钉连接件的峰值荷载比多根自攻螺钉连接件中单颗螺钉的峰值荷载高约30%;剪力垂直于螺钉边距方向且单向受拉工况下,螺钉边距对连接件峰值荷载的影响较大,螺钉边距每增加5 mm,连接件峰值荷载增加约30%;单向拉伸工况、剪力平行于螺钉边距方向时,连接件的峰值荷载和峰值位移较大;采用Foschi指数函数模型拟合连接件的骨架曲线,与试验结果吻合较好,为冷成型钢结构体系数值模拟研究提供了连接件性能基本参数。     

夹芯墙板覆面冷弯薄壁型钢承重复合墙体受剪试验

为满足多层冷弯薄壁型钢房屋建筑的抗震及防火要求,同时兼顾施工便捷性,提出了夹心墙板覆面的新型冷弯薄壁型钢复合墙体,并完成了11片足尺模型水平加载试验。试验表明： 1） 复合墙体的受剪破坏主要由墙板周边的螺钉连接失效引起,即螺钉将墙板撕裂或螺钉剪断引起,墙板与自攻螺钉之间的连接力学性能成为影响复合墙体受剪性能的主要因素;增大墙板厚度或者采用玻镁板代替石膏板可提高复合墙体抗剪性能,而龙骨立柱的截面尺寸对复合墙体受剪性能影响不明显; 2） 同侧墙板层数的增加对复合墙体受剪承载力及刚度虽有明显提高,但未达到线性叠加程度;夹心墙板的使用有利于墙体蒙皮效应的发挥,相应的墙体受剪性能优于墙体同侧双层墙板覆面时的受剪性能; 3） 蒸压加气混凝土（ALC）板周边与自攻螺钉的连接区域在较低水平荷载作用下出现板材开裂现象,故不宜采取ALC板参与墙体受力的连接方式。研究给出了新型冷弯薄壁型钢复合墙体的受剪承载力及抗剪刚度设计指标,供工程设计参考。     

LQ550高强冷弯薄壁型钢组合墙体受剪性能试验研究

为研究OSB板和水泥纤维板作为LQ550高强冷弯薄壁型钢组合墙体结构面板时的受力性能,进行7个不同结构面板的LQ550高强冷弯薄壁型钢组合墙体试件的水平单调加载和低周反复加载试验研究,分析了组合墙体的受剪承载力、延性系数、耗能系数等。结果表明：面板拼缝是组合墙体的薄弱部位;在水平接缝处设置宽而完整钢衬板的墙体试件具有较高的受剪承载力和抗侧刚度;单面水泥纤维板单调加载时比低周反复加载时承载力提高约8.79%~12.27%,其受剪承载力较低,但屈服前试件基本完好;对于双面板墙体试件,无论在单调加载还是反复加载时,其承载力、抗侧刚度约为各单面板试件相应指标之和。低周反复加载试件的耗能系数基本接近。     

高强冷弯型钢骨架墙体抗剪性能试验研究

对550MPaC型冷弯型钢立柱、550MPa带肋钢板和石膏板组成的高强冷弯型钢骨架墙体进行了16块足尺试件(宽2.4m,高3m)的抗剪试验研究。对带肋钢板+石膏板双面板、单面带肋钢板、单面石膏板和双面无板带交叉扁钢拉条支撑4类墙体试件进行了无竖向力水平单调加载、无竖向力水平低周反复加载和有竖向力水平低周反复加载的试验,得到了各类墙体试件的受剪承载力指标和位移延性系数μ等性能指标。试验结果表明:各类墙体单调加载试件抗剪强度均比反复加载试件高;单面石膏板墙体试件与0.8倍的单面带肋钢板墙体试件的承载力指标之和与双面板墙体试件承载力指标接近;双面无板带交叉扁钢拉条支撑墙体试件抗剪强度是双面板墙体试件的60%~67%;双面板墙体试件延性系数在1.731~2.384之间。     

ALC拼合墙板受剪性能试验研究和有限元分析

蒸压轻质加气混凝土(ALC)拼合墙板由成品单板通过板间灌浆拼接,并以特定的连接工法(构造)和钢结构连成整体,其面内剪切性能不同于整面成型板材。遵循单板拼合界面连接、墙板、墙板与钢结构协同工作递进的试验研究方法,进行了4个界面纯剪试验、6个拼合墙板面内单调剪切试验以及1个墙板和钢框架协同工作的单调和反复加载试验。试验结果表明:影响墙板自身剪切性能的主要因素为拼合界面的粘结性能、连接工法的钩头螺栓布置方式、墙板和灌浆的材性;协同工作时具有代表性的底层墙板侧向刚度贡献率为21.6%;试验全程钩头螺栓连接完好。对各阶段试验进行了接触有限元数值分析,用接触法向刚度因子FKN模拟拼合界面粘结程度,结果和试验吻合较好。     

加筋砌块墙的抗弯和抗剪特性

本文介绍了国外在单冲和交变侧向荷载的作用下,加筋砌块剪力墙的抗弯和抗剪性能的研究成果.该研究是以20多块1.83×1.83m加筋砌块墙板,在平面内的垂直和侧向荷载下的试验结果为依据的.矮剪力墙的抗弯强度和变形能力可根据平截面的假设,用简单的弯曲理论来进行准确的计算.此外,由斜裂缝控制的抗剪强度破坏可归结为几种复杂的机理(或成因).     

钢带加强螺钉孔型冷弯型钢组合墙体抗震性能

为研究钢带加强螺钉孔对冷弯型钢组合墙体抗震性能的影响,对3个冷弯型钢组合墙体足尺试件进行低周反复加载试验,分析该加强形式对冷弯型钢组合墙体的破坏模式、侧向刚度、承载能力、延性以及耗能性能的影响。同时采用有限元软件OpenSEES对墙体进行数值分析。结果表明:钢带加强螺钉孔型冷弯型钢组合墙体的破坏形式仍然为螺钉连接失效和板缝滑移,钢带能够使覆面板的螺钉连接处得到加强,从而提高组合墙体的抗侧刚度和受剪承载力; 与螺钉孔未进行钢带加强的墙体试件(HS-140-A)相比,2个加强式的组合墙体试件(HS-140-B,HS-140-C)受剪承载力分别提高了32.5%,58.1%,抗侧刚度分别提高了31.7%,59.3%; 螺钉孔由钢带加强后,墙体试件的耗能性能显著提升; 3个试件的延性系数均大于8,呈现出良好的变形能力; 有限元模型能反映螺钉连接非线性行为对墙体滞回性能的影响,有限元分析结果与试验结果的相对误差控制在10%以内,模型具有较好的精度。     

带外加强环不等高梁-钢管混凝土柱组合节点抗震性能试验研究

对4个带外加强环不等高梁钢管混凝土柱节点试件进行了循环加载和单调加载试验,试件主要变化参数为节点两侧梁高度差,取值为 0、75、 150mm。为了研究节点域的受剪承载力,对试件按“强构件,弱节点”进行设计。对于所设计的4个节点试件,其破坏分为整个节点域剪切破坏和部分节点域剪切破坏。试验结果表明：加载方式对试件节点域剪切承载力影响不大;节点试件在正反两个方向加载形成不同的破坏模式,并且在反向荷载作用下其承载力略高于其在正向荷载作用下的承载力;节点两侧梁高度差对节点域破坏形式和承载力影响显著;在整个加载过程中,所有试件节点均未出现开裂;该类节点具有很好的变形能力和稳定的耗能能力,但随着两侧梁高度差的增加,耗能能力逐渐降低。     

Experimental analysis on strength and failure modes of wood beam-column connections

This research experimentally examined the strength, failure modes, and behaviors of dowel-bearing and fiber-bearing wood beam-column connections and explored the effects of cyclic loading on the strength, failure modes, and behaviors of those connections. Base on limited numbers of exploratory laboratory tests (6 preliminary tests in total), the authors observed that the typical bolted connection (dowel-bearing type wood beam-column connection with fiberbearing surfaces) showed good behavior (large peak moment) under the monotonic loads, and the tenon joint connection (fiber-bearing wood beam-column connection) showed good behavior under cyclic loads. The cyclic property of loading reduced the strength of the dowel-bearing type wood beam-column connections, but increased the strength of fiberbearing type wood beam-column connections. More importantly, the authors identified a possible location of safety concern in current national design specifications (NDS) standards for the typical bolted connection (dowel-bearing connection with fiber bearing surface) under cyclic loading because the tested value was smaller than the NDS calculated value. But, because of the small amount of tests conducted, no final conclusion can be drawn based on those preliminary observations yet. A large number of repetitive laboratory tests should be conducted.     

Detailing recommendations for 1.83 m wide cold-formed steel shear walls with steel sheathing

The paper presents an experimental investigation on 1.83 m wide, 2.44 m high cold-formed steel (CFS) stud framed shear walls using steel sheet sheathing. Four wall configurations were studied through monotonic and cyclic tests. The test results indicated that besides the sheet buckling and screw pull out, the buckling of interior studs might occur for the 1.83 m CFS walls. To prevent the failure in the studs, special detailing was developed in this research. It was discovered that the special detailing could increase both the shear strength and the ductility of the shear walls. The research also found that the codified nominal shear strengths can be conservatively used for walls with an aspect ratio of 3:2. Based on the test results, the nominal seismic shear strength for 1.83 m wide CFS shear walls was established for design purposes.     

铝合金板剪力墙抗震性能研究

传统钢板剪力墙的周边框架和内嵌板均采用普通钢材。随着耗能抗震理念的发展,将内嵌板中的普通钢板替换成低屈服点的铝合金板,组成铝合金板剪力墙。采用数值方法研究铝合金板剪力墙在单调荷载作用下的抗剪性能和在低周反复荷载作用下的滞回性能。研究显示:与普通钢板相比,铝合金板更易发生剪切屈曲不先于剪切屈服,对周边框架的要求更低且耗能性能更好。     

蒸压纤维水泥板覆面轻钢龙骨式复合墙体抗剪性能试验研究

为研究采用蒸压无石棉纤维素纤维水泥板(CCA板)覆面的轻钢龙骨式复合墙体的抗剪性能,进行了13片足尺墙体的水平单调加载和低周反复加载试验。试验结果表明,采用CCA板覆面轻钢龙骨式复合墙体的破坏主要表现为自攻螺钉连接处的CCA板拉裂或者螺钉拔出,最终CCA板失去传递剪力的能力而破坏,轻钢龙骨未发生明显破坏。基于试验结果,得到了各类CCA板覆面墙体的屈服荷载、最大荷载、破坏荷载以及位移延性系数等性能指标。最后,分析了CCA板厚度、密度以及加载方式对轻钢龙骨式复合墙体受剪性能的影响,并与OSB板、石膏板覆面墙体进行了比较。     

冷弯薄壁型钢组合楼盖和自攻螺钉连接的抗剪性能试验研究

对3个足尺冷弯薄壁型钢楼盖试件的面内受力性能进行了水平低周往复加载试验研究,得到其破坏特征、承载力指标以及自攻螺钉连接的破坏模式,试验结果表明C形边梁与压型钢板间的自攻螺钉连接破坏导致了楼盖试件破坏。基于楼盖试件面内破坏现象,对C形楼盖梁与U形边梁间、C形楼盖梁与压型钢板间两种自攻螺钉连接形式进行了抗剪性能试验研究,得到自攻螺钉连接的破坏形态和单颗自攻螺钉的抗剪承载力,分析了中国规范GB 50018-2002对于计算单颗自攻螺钉抗剪承载力的适用性。采用基于性能的抗震设计理论对冷弯薄壁型钢楼盖中自攻螺钉连接的性能水平、性能目标以及承载力指标进行了探讨,其结果可用于指导冷弯薄壁型钢结构体系的抗震设计。     

榫接木框架剪力墙受剪性能试验研究

通过对7组14个木框架剪力墙试件进行单调和反复加载受剪性能试验研究,分析了不同墙骨连接方式、是否开设洞口及不同材料对木框架剪力墙的受剪承载力、弹性抗侧刚度、极限位移、耗能的影响。试验结果表明：墙骨柱采用榫接的连接方式,能有效避免在循环荷载作用下墙骨柱与底梁板钉接时的连接失效,保证墙体框架整体性;榫接连接对于提高墙体刚度、控制变形有显著作用;墙体开设洞口会显著降低墙体刚度,增大墙体的耗能能力。采用国产胶合板的墙体具有良好的受剪性能,可以作为进口OSB板的替代板应用于剪力墙建造。     

Experimental study of low-yield-point steel plate shear wall under in-plane load

This paper describes the study of the low-yield-point (LYP) steel plate shear walls under in-plane load. In the LYP steel plate shear wall system, LYP steel was selected for the steel plate wall while the boundary frame was constructed by the high strength structural steel. A series of experimental studies examined the inelastic shear buckling behavior of the LYP steel plate wall under monotonic in-plane load. The effects of width-to-thickness ratio on the shear buckling of LYP steel plates were examined. The stiffness, strength, deformation, and energy dissipation characteristics were investigated by performing cyclic loading tests on the multistorey LYP steel plate shear walls. Excellent deformation and energy dissipation capacity were obtained for all specimens tested. The LYP steel plate shear wall system is able to exceed 5% of storey drift angle under lateral force.     

Experimental and numerical study on cyclic behaviour of steel beam-to-column joints

Ten specimens are tested to investigate the cyclic behavior of beam-to-column joints of steel frames with joint panels. The performances of the joints with respect to strength, rigidity, and hysteretic performance are examined. Three different load-carrying mechanisms can be identified. Panel resistance ratio (R _p ) is presented for predicting the buckling patterns. The validity ofR _p is confirmed through the present experimental results. On the basis of the experimental results of steel beam-to-column moment joints, 3-D nonlinear finite element models are established to analyze the mechanical properties of these connections. The load-displacement curves of the finite element analysis are in good agreement with those of the tests in terms of strength and unloading stiffness. A shear lag phenomenon was captured in the beam flanges by not only experimental results but also numerical analysis. Parametric studies are conducted on the connections under monotonic loading to investigate the influences of connection dimension, resistance ratio on the connection behavior. It was found that the failure modes are influenced by the resistance ratio, while the thickness of joint panels resulting in large effects on the strength and stiffness under shear failure mode.     

Seismic behavior of connections composed of CFSSTCs and steel-concrete composite beams — finite element analysis

Based on the experimental results of connections composed of concrete-filled square steel tubular columns (CFSSTCs) and steel-concrete composite beams with interior diaphragms, exterior diaphragms, or anchored studs, 3-D nonlinear finite element models were established to analyze the mechanical properties of these three types of connection using ANSYS. Finite element analyses were conducted under both monotonic loading and cyclic loading. The load-displacement and shear force-deformation curves of the finite element analyses are in agreement with those of the tests in terms of strength and unloading stiffness. Parametric analyses were conducted on the connections with exterior diaphragms under monotonic loading to investigate the influences of axial load ratio, width to thickness ratio, and dimensions of exterior diaphragms on the connection behavior. It was found that the strength and stiffness are less influenced by the axial load ratio and the dimensions of the exterior diaphragms, but more influenced by the width to thickness ratio of the steel tube under shear failure mode.     

自攻螺钉参数设置对胶合木梁柱节点受力性能的影响

采用自攻螺钉对胶合木梁柱节点进行横纹加强可有效传递木材的横纹拉应力和顺纹剪应力,从而延缓木材开裂、提高节点性能。为了研究自攻螺钉的布置间距、直径和个数等参数对加强节点受力性能的影响,对4组采用不同布置间距、直径和个数的自攻螺钉加强胶合木螺栓连接梁柱节点进行单调和低周往复加载试验,得到各组节点的刚度、延性、承载力、破坏模式和抗震性能。结果表明：自攻螺钉个数增加、直径增大,节点的承载力、破坏转角、延性系数以及节点总耗能增大;自攻螺钉布置间距的变化对节点在单调荷载作用下的承载力和延性系数无明显影响;而节点在往复荷载作用下时,随着自攻螺钉布置间距的减小,节点承载力和总耗能降低。     

螺栓连接全装配式一字形RC剪力墙受力性能试验研究

采用高强度螺栓和连接钢框连接上下层预制钢筋混凝土（RC）墙板,形成一字形全装配式剪力墙。为了研究该全装配式剪力墙的基本力学性能及水平接缝的工作机制,以连接钢框的翼板厚度及高强度螺栓的公称直径及预拉力为参数,制作3个试件,进行了单调加载试验,对试件的水平荷载－侧移曲线及其特征点、钢筋应变、连接钢框与内嵌边框之间的相对滑移以及连接钢框的应变分布进行了分析。试验结果表明：采用螺栓连接的全装配式剪力墙具有较好的延性性能;减小高强度的螺栓直径及预拉力会使水平接缝内的相对滑移增大;减小连接钢框的翼板厚度会使连接钢框中的应力增加;连接钢框受压区的正应力远大于受拉区,受拉区与受压区分界点的位置与预制墙板基本一致。在试验的基础上,分析了水平接缝的工作机制。分析表明：摩擦作用、销栓作用是受拉区水平接缝传递荷载的主要方式;受压区水平接缝的工作机制与连接件之间的初始空隙有关,摩擦作用、销栓作用以及顶紧挤压作用是受压区水平接缝传递荷载的主要方式。