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.     

弱轴顶底角钢连接滞回性能的非线性有限元分析

在钢框架结构中,弱轴连接与强轴连接同样普遍[1],目前对钢框架强轴连接的研究较多,但弱轴连接的研究资料却十分匮乏。因此,本文作者采用有限元方法,先对弱轴顶底角钢连接在单向加载下的性能进行非线性分析,并与文献[1]中试验结果对比。再设计6个试件,采用多线性随动强化材料模型,研究该节点在往复荷载作用下的滞回性能。着重分析角钢厚度、柱腹板厚度对其滞回性能的影响。研究结果表明,弱轴顶底角钢节点属于典型的半刚性连接,连接刚度较小,节点延性较好,有一定的耗能能力。     

半刚性框架-大高宽比钢板剪力墙抗震性能研究

在半刚性框架-大高宽比钢板剪力墙体系中,半刚性框架和内填钢板均具有很好的延性和耗能性能,两者协同工作进行抗侧以防止结构在地震作用下破坏。为深入研究半刚性框架-大高宽比钢板剪力墙的力学性能,采用ANSYS有限元分析软件对结构进行数值分析,并考察框架节点形式,内填钢板高宽比、高厚比,柱轴压比和肋板刚度比等一系列参数对结构滞回性能的影响。根据内填钢板中心点在循环荷载作用下的面外变形,研究半刚性框架-大高宽比钢板剪力墙的屈曲性能和受力机理。     

梁柱盖板连接的滞回性能研究

盖板加强式梁柱刚性连接节点是使塑性铰外移以提高节点塑性变形的一种改进形式。为了研究梁柱盖板连接的滞回性能,在考虑材料、几何和接触状态非线性基础上,采用三维实体单元对梁柱盖板连接进行了循环加载有限元模拟。设计了4组共12个试件,研究了节点域厚度、梁高、盖板长度及轴压比等参数对盖板连接滞回性能的影响。有限元分析结果表明:大部分节点表现出良好的延性,梁端位移超过80mm;节点域厚度越厚,连接的承载力和刚度越高;梁高越大,连接的延性越差,可能会发生强梁弱柱破坏;盖板长度对节点性能没有显著影响;轴压比越大,节点的强度、刚度和延性会显著降低。     

Collapse resistance of unreinforced steel moment connections

Experimental and analytical studies of steel moment connections in gravity load resisting systems were conducted to understand the connection behaviour under progressive collapse. An exterior beam–column assemblage was selected from the gravity load resisting system in a steel building. Two identical, full‐scale, unreinforced welded steel beam‐to‐column moment connection specimens were tested under monotonic and cyclic loading to investigate the effects of applied loading conditions on the connection rotation capacity. The beam web was connected to the column flange by bolting and the beam flanges were complete joint penetration welded to the column flange. The specimens failed by fracture in the beam flange CJP weld at story drifts of 9.2 % (specimen SP1 under monotonic loading) and 3.4% (specimen SP2 under cyclic loading). The maximum drift angle achieved in the monotonic test exceeded the General Service Administration criterion for welded unreinforced flange connections, and the amount of dissipated energy of SP1 turned out to be smaller than that of SP2. The finite element analysis of the test specimen was also conducted to validate the test results, and the analysis results matched well with those obtained from experiments. Copyright © 2010 John Wiley & Sons, Ltd.     

Seismic behavior of connections composed of CFSSTCs and steel-concrete composite beams—experimental study

In order to investigate the seismic behavior of connections composed of concrete-filled square steel tubular columns and steel-concrete composite beams, fourteen cruciform connection specimens were tested. The strength, deformation, and energy dissipation capacity of these composite connections were analyzed. The test results showed that the strength of connections with interior diaphragms is adequate, but their ductility is low. Also, the deformation capacity of connections with anchored studs is good, but their strength is low. In comparison, the connections with exterior diaphragms have adequate strength, good ductility, and high-energy dissipation capacity, and as a result, it can be concluded that they are more suitable for applications in moment resisting frames in seismic regions.     

方钢管混凝土柱与钢-混凝土组合梁连接的内隔板式节点的抗震性能试验研究

为研究方钢管混凝土柱与钢-混凝土组合梁连接的内隔板式节点的抗震性能,本文对3个节点试件进行了低周反复荷载试验,在此基础上对节点的受力过程、破坏形态、滞回曲线、骨架曲线、变形恢复能力、延性、刚度退化和耗能能力等抗震性能进行了较为深入的研究与分析。试验结果表明:内隔板式节点能够有效地传递梁端弯矩及剪力,其滞回曲线呈明显的梭形,单周耗能能力较强;节点在梁端塑性铰破坏模式下具有较好的承载力、耗能性能及滞回特征,而在剪切破坏及局部焊接破坏模式下则延性较低,抗震性能相对较差;节点在整个加载过程中刚度退化明显,持续均匀,同时表现出一定的变形恢复能力;楼板组合作用对于节点的抗震性能具有一定程度的影响。     

拉压变轴力下小剪跨比预应力混凝土墙往复受剪试验研究

为了研究预应力混凝土（PC）剪力墙的抗震性能,提出剪力墙在拉压变轴力作用下的水平往复加载试验加载制度,完成3片剪跨比为1.0的预应力混凝土墙在恒定轴拉力、恒定轴压力和拉压变轴力作用下的水平往复加载试验,研究其破坏模式、滞回性能、承载力、变形能力、刚度和残余裂缝宽度,并与型钢混凝土（SRC）墙和普通RC墙的抗震性能进行了对比。试验结果表明：恒定轴拉力试验中,预应力混凝土墙发生了腹板剪切破坏;恒定轴力试验中墙体发生了斜压破坏;拉压变轴力试验中,墙体在压剪方向加载时发生剪压破坏。拉压变轴力加载导致预应力混凝土墙拉剪和压剪承载力分别降低了18.7%和10.5%。预应力混凝土墙在恒定轴拉力和拉压变轴力作用下的极限位移角为1.2%~1.6%,变形能力大于JGJ 3—2010《高层建筑混凝土结构技术规程》规定的弹塑性位移角限值(1/100);恒定轴压力试验中水平峰值荷载超过了墙体截面受剪承载力限值,出现斜压破坏,极限位移角仅为0.6%。预应力混凝土墙试件与SRC墙试件的刚度、承载力和变形能力接近,前者的残余裂缝宽度小于后者的,表现出更好的震后可修复性。由于预应力有效抑制了墙体水平贯通裂缝的形成、防止出现沿水平裂面的滑移破坏,因此在较大轴拉力水平时预应力混凝土墙比普通RC墙的抗侧刚度和承载能力均显著提高。总体来看,预应力混凝土墙抗震性能优良,是一种改善高层建筑中受拉剪力墙抗震性能的有效手段。     

方钢管混凝土柱节点抗剪受力性能的研究

为研究方钢管混凝土柱与钢-混凝土组合梁连接节点的破坏特征和抗震性能,进行了3个内隔板式节点、2个外隔板式节点和1个栓钉内锚固式节点的低周反复荷载试验。在此基础上,对方钢管混凝土柱节点的抗剪受力性能进行了分析,将节点域抗剪贡献分为三部分进行研究,包括:节点域钢管腹板的抗剪贡献、节点域钢管翼缘与内隔板或外隔板组成的钢板框架的抗剪贡献以及节点域混凝土的抗剪贡献,由此得到了相应各部分剪力-剪切变形曲线的计算方法。根据剪切变形协调的条件将上述三部分曲线进行叠加,就可以得到节点的剪力-剪切变形骨架线。此后,提出了卸载线和再加载线的简化确定方法,从而得到了方钢管混凝土柱节点剪力-剪切变形曲线的恢复力模型。理论模型与多组试验结果相比,基本吻合,虽然在再加载刚度和耗能性能方面存在一定的误差,但是整体而言仍然具有参考意义。在此基础上,提出了方钢管混凝土柱节点屈服抗剪承载力和极限抗剪承载力的计算公式,从而为工程设计提供了实际依据。     

分布式连接全装配钢筋混凝土楼盖板缝节点平面内受力性能试验研究

为研究分布式连接全装配RC楼盖板缝节点平面内受力性能,进行了5种共18个板缝节点在平面内水平单调荷载、低周反复荷载和拉剪复合作用下的足尺模型试验,对板缝节点的受剪承载能力、破坏形态、滞回曲线、位移延性、耗能能力和拉剪复合受力性能进行了较为系统的研究。研究表明：除SPC和SP-CPC节点外其他3种板缝节点均具有较好的受剪承载力和刚度,且节点承载力可由叠加法简化计算;HPC节点、CPC节点和HP-CPC混合式节点具有较好的滞回性能、耗能能力和位移延性,是较为合理的板缝连接节点形式;拉力的存在削弱了板缝节点受剪承载力,且拉剪比越大削弱程度越高;高拉剪比下节点的延性较差,在极限荷载下易发生类似螺栓群连接中的“连锁破坏反应”,设计时需对高拉剪比区的连接件进行改进和加强,以满足楼盖对板缝节点延性的要求。     

弯剪受力下群锚有限元分析

采用型钢—混凝土后锚固连接方式,对弯剪受力下粘结型锚栓群的受力性能进行了试验研究和有限元分析。结果表明,该类连接的破坏形态为锚栓钢材破坏,仅锚栓周围混凝土发生锥体破坏,锚栓内力以拉应力为主。锚固承载力随着埋深的增加而提高,加载端至基材表面的水平距离较大时,弯矩起控制作用,承载力较小;水平距离较小时,则表现为弯剪共同作用,承载力较大。     

Seismic behavior of composite connections — flexural capacity analysis

Based on the experimental results of connections composed of concrete-filled square steel tubular columns and steel-concrete composite beams with interior diaphragms or anchored studs, the flexural capacity of connections is studied theoretically in the present paper. Analytical models are proposed, with consideration of the effects of axial load, concrete slab, middle interior diaphragm, beam and column width condition, and punching shear failure mode. Formulae in different conditions are established based on these models. The predictions and the test results are compared and they are in good agreement.     

两边连接屈曲约束钢板剪力墙受力机理与等效支撑模型

采用理论分析和有限元方法,针对两边连接屈曲约束钢板剪力墙的受力机理和传力规律进行研究。提出了钢板墙边缘约束区的概念并确定了边缘约束区的宽度,分析了钢板墙的屈服形状、钢板墙内各部分应力流的分布规律和钢板墙与梁连接处的受力特点等。在此基础上提出了两边连接屈曲约束钢板剪力墙等效支撑模型,对不同尺寸、不同层数的框架 屈曲约束钢板剪力墙结构和框架 等效支撑结构在水平荷载作用下的力学性能进行分析,并对两种结构的荷载 位移曲线进行了对比。分析表明,所提出的等效支撑模型在结构刚度和承载力方面具有较好的准确性,无论是单调加载还是反复加载均能准确地模拟两边连接屈曲约束钢板剪力墙结构的受力行为。     

Experimental study of screw connections in CFS-calcium silicate board wall panels

Cold-formed steel (CFS) wall panels with different board materials are used extensively in residential and commercial buildings to resist lateral loads by in-plane shear, in addition to helping the studs resist gravity loads. Generally the screw connection between the board and CFS skeleton frame, which experience shear, dictates the behaviour and strength of such panels. In this paper, details of an experimental study on behaviour and strength of the screw connections between the cold-formed steel profiles and calcium silicate boards, under monotonic and cyclic shear loading, are presented. The objectives of the experimental study are: (a) to develop a new test procedure that realistically represents the behaviour and failure of screw connections in CFS wall panels; (b) to investigate the effect of edge distance of the screws and thickness of the boards on behaviour and strength; (c) to study behaviour under monotonic and cyclic loading; (d) to develop the values of the important parameters that determine the load–deformation behaviour of the screw connection in such wall panels under in-plane shear; and (e) to develop design equation to evaluate the ultimate shear strength and its resistance factor required in load resistance factor design (LRFD).     

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。     

方钢管混凝土柱-外包钢混凝土组合梁连接节点滞回性能分析

提出了一种新型的方钢管混凝土柱与外包U形钢混凝土组合梁连接节点形式：隔板贯通部分钢筋贯穿式节点。设计了3个节点试件,对其进行低周反复荷载试验,利用ANSYS软件对低周反复荷载作用下的节点试件进行非线性有限元分析并与试验结果对比。结果表明:有限元分析得到的节点破坏形态、应力分布、滞回曲线、骨架曲线与试验结果吻合较好。在此基础上,对发生梁端塑性铰破坏模式的节点滞回性能进行参数分析,研究楼板厚度、U形钢壁厚、组合梁纵向受力钢筋配筋率、贯通隔板厚度以及轴压比对节点滞回性能的影响。研究结果表明：楼板厚度和U形钢壁厚对节点滞回性能有显著的影响,组合梁纵向受力钢筋配筋率对节点滞回性能影响较为显著,贯通隔板厚度和轴压比对节点滞回性能影响很小。     

考虑加载制度影响的狗骨式连接钢框架子结构抗震性能试验研究

为研究加载制度对狗骨式连接钢框架结构变形能力及累积耗能能力的影响,设计了5榀单跨狗骨式连接钢框架子结构,对其进行单向加载、等位移循环加载、标准加载及近场地震动作用下的拟静力试验。结果表明：所有框架出现的塑性铰均在钢梁端部的翼缘削弱位置,避免了钢梁端部焊缝的过早脆性断裂;狗骨式连接钢框架结构滞回曲线饱满、变形能力及延性性能优良。此外,加载制度对狗骨式连接钢框架子结构的层抗侧刚度、水平承载力退化、极限变形能力及累积耗能能力均有显著影响。等位移循环时,加载位移幅值越小,狗骨式连接钢框架子结构的层抗侧刚度及承载力退化越趋于缓慢,其层间累积延性系数及等效能量耗散系数越大。     

异形钢管混凝土组合柱的抗震性能

对轴向恒荷载和循环弯曲荷载作用下异形钢管混凝土异形组合柱(SCFST柱)的性能进行了试验研究。研究SCFST柱的轴压比和长宽比对其性能(刚度、强度、延性以及能量耗散)的影响,并对组合柱的不对称性进行了研究。连接板是传递剪力的主要构件。SCFST组合柱的各构件协同工作,具有较好的抗震性能。随着轴压比的增加,SCFST组合柱的刚度增大,耗能能力、延性和承载能力降低;另一方面,随着长宽比的增加,其耗能能力和延性增加,刚度和承载能力降低。此外,对SCFST柱的性能进行了有限元模拟,其结果与试验结果相吻合。     

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。