WUF-W connection performance to box column subjected to uniaxial and biaxial loading

The prequalified connections presented in AISC are limited to the connections of the I beam to wide flange columns. It is necessary to investigate the seismic performance of the prequalified connections to the box column, which has a very low strength and stiffness panel zone in contrast with the wide flange column. In this study, the seismic behavior of the WUF-W (welded unreinforced flange) connection to the box column was investigated through full-scale cyclic loading tests. The experimental results revealed that this type of connection to the box column can satisfy the prequalified criteria of the special moment frame. Moreover, the main advantage of using box column is its high biaxial bending strength. Therefore, as part of the analytical study, the connection subjected to biaxial loading for a series of parameters was investigated. The analytical investigation showed that in order to achieve the desired performance under biaxial loading, the panel zone must provide the strong column/weak beam ratio of more than what is suggested by AISC. Furthermore, the analytical study revealed that for the box column under biaxial loading, the inner diaphragm may not be suitable because of the potential for the weld to fracture.     

梁端翼缘扩大型连接的抗震性能研究

通过试验及数值分析方法研究了钢框架梁端翼缘扩大型连接节点的滞回性能、极限承载力、破坏模式、刚度及强度退化等抗震性能。研究结果表明:梁端翼缘扩大式节点可以将塑性铰转移到梁翼缘扩大端截面以外位置,避免梁端焊缝发生脆性破坏;加强侧板末端截面有明显突变和热影响区影响使钢材变脆应力集中现象严重,制约了节点塑性耗能深入发展;直接扩翼型节点塑性铰中心形成于扩翼圆弧段末端,远离柱翼缘,达到了塑性铰外移的目的;在循环荷载作用下,翼缘及腹板随局部屈曲塑性变形的不断积累,导致试件的强度出现退化;节点构造形式对抗震性能影响显著,直接扩翼型节点的塑性变形和耗能能力较好,推荐在强震区采用。     

未补强焊接梁柱接头之应用于箱形柱

探讨钢结构特殊弯矩构架梁柱接头的耐震行为,梁柱接头采用未补强焊接梁柱接头,特点在于厚梁翼板、箱形柱断面、且焊接扇形孔采用美国AWS的建议,以盼能提供良好的韧性行为。以试验方法进行两组实尺寸试体的试验,梁柱子结构承受反复载重。试验结果显示,两组试体皆可达4%弧度层间变位角,梁发展塑性弯矩强度;破坏肇因于梁翼全渗透焊道裂缝造成的撕裂。研究成果提供预审合格梁柱接头更广泛的实务应用。     

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.     

H形梁翼缘双肋板加强式弱轴连接的抗震性能分析

提出了一种适用于工字形柱箱形节点域的H形梁翼缘双肋板加强式弱轴连接;应用ABAQUS有限元软件对标准节点、梁翼缘外侧双肋板加强式节点和梁翼缘内侧双肋板加强式节点共7个足尺计算模型进行了力学性能分析,研究了节点破坏模式、滞回特性、骨架曲线、耗能能力、塑性转动能力和延性等问题。结果表明:箱形节点域双肋板加强式弱轴连接能够有效地在梁端形成塑性铰,并且塑性铰远离节点核心区,从而实现强柱弱梁和强节点弱构件的抗震理念;梁翼缘内侧双肋板加强式节点可以达到与梁翼缘外侧双肋板加强式节点相同的抗震性能,并且改善了梁柱翼缘对接焊缝的应力;梁翼缘双肋板加强式节点的耗能能力和延性系数都有显著提高,塑性转动能力达到FEMA 267建议的0.03 rad,符合国际上对节点塑性转动能力的要求。     

复式钢管混凝土柱与H形钢梁连接节点抗震性能试验研究

借鉴方钢管混凝土柱-钢梁外肋环板节点形式,将非梁柱连接面的柱两侧外肋环板改为竖贴于柱侧的竖向肋板并伸出与梁翼缘焊接,同时设置锚固腹板,形成复式钢管混凝土柱与H形钢梁连接节点。通过7个梁柱组合体试件的低周反复荷载试验,分析各试件的破坏过程及特征,并对试件的滞回性能、承载力、延性、耗能能力和承载力及刚度退化等抗震性能进行研究。研究结果表明：节点的破坏形态基本相同,梁端先屈曲,形成塑性铰;锚固腹板可有效提高节点的承载力和变形能力;竖向肋板外伸长度可提高试件的初始刚度,使梁端塑性铰外移,有效保护节点核心区;试件的滞回曲线呈明显的梭形,具有良好的承载力、延性及耗能能力;试件在整个加载过程中刚度退化现象明显,承载力退化很小,可应用于抗震设防地区。     

组合效应对高层钢框架梁柱节点脆性破坏的影响分析

美国北领地震中,不少钢框架梁柱连接出现了意想不到的脆性破坏。观察表明,大部分破坏发生在节点区的梁下翼缘与柱翼缘之间的全熔透焊缝以及相邻板件的焊缝热影响区。由此可知,焊缝质量不良是节点断裂的主要因素。此外,连接缺乏有效的延性也是破坏的一个原因。节点抗震性能试验中多数采用的是钢节点,没有考虑钢梁上的混凝土板。实际结构中,混凝土楼板的存在提高了节点连接的强度和刚度,这也就加剧了下翼缘发生脆性破坏。通过有限元方法,分析了混凝土板组合效应对梁柱节点脆性破坏的影响。     

钢筋混凝土带翼墙短柱抗震性能研究

本文通过１２个试件试验、电算和机理分析，对钢筋混凝土带翼墙短柱抗震性能进行研究。试验以剪跨比、轴压比和翼墙宽度为变参数，采用单调和低周往复两种方式施加水平荷载。电算采用三维实体单元，对弹性状态下这种柱的受力特点和变参数影响进行了分析。对试验中出现的各种破坏形态进行了机理分析，并建议了相应的水平极限承载能力计算公式及界限剪跨比。研究结果表明：翼墙充分参加工作，改变了柱的受力与破坏形态，使柱的承载能力提高，变形能力降低；电算、公式计算和试验结果符合良好。     

Internal flange stiffened moment connections with low-damage capability under seismic loading

This study presents the seismic performance of steel moment connections using internal flange stiffeners (IFSs) welded at the face of the wide-flange column and inner side of the beam flange. The objective is to develop a steel moment connection that can achieve good seismic performance with low-damage capability during a large earthquake loading and minimize the repair cost. Four large-scale moment connections were tested to validate the cyclic performance. One connection which represented a welded-unreinforced flange-bolted web connection failed before finishing cyclic tests at a drift of 4%. Three IFS moment connections showed excellent performance and low damage after experiencing the AISC seismic load twice up to the target drift of 4%, without strength reduction. The specimens were also modeled using the computer program ABAQUS to further verify the effectiveness of the IFS in transferring beam moment to the column and to investigate potential sources of connection failure.     

钢梁和箱型柱间翼缘板连接件的抗震性能

对钢梁和焊接箱型柱间的翼缘板连接件的滞回性能进行分析和试验研究。对3个足尺试件模型进行试验,从而评估翼缘板长度和板-翼缘角几何焊接对翼缘板连接件地震响应的影响。试验所用的翼缘板连接件符合AISC中对于特殊抗弯框架的抗震要求。因此,使用试验结果验证ABAQUS软件建立的有限元模型,此模型可用于对试件模型性能的进一步探讨。     

翼缘削弱型节点空间钢框架在低周反复荷载

为研究翼缘削弱型节点空间钢框架在低周反复荷载作用下的抗震性能,采用有限元分析软件ABAQUS对普通节点和翼缘削弱型节点的空间钢框架模型进行有限元模拟,对2种钢框架模型的破坏形式、承载力、滞回性能、耗能能力、强度及刚度退化性能等进行了对比分析。结果表明:翼缘削弱型节点可使梁端塑性铰外移至梁端翼缘削弱处,避免梁端焊缝处应力集中导致脆性破坏;翼缘削弱型节点等效粘滞阻尼系数与普通节点空间钢框架相比有明显的提高,进入屈服阶段后由于应力重分布,其刚度及承载力退化速度较普通节点空间钢框架慢,翼缘削弱型节点钢框架具有梁铰延性破坏机制,抗震性能较好。     

带悬臂梁段拼接的梁柱连接循环荷载试验研究

为了检验带悬臂梁段拼接的梁柱连接抗震性能,对4个试件进行了循环加载试验。试验侧重于对拼接节点的研究,采用10.9级高强螺栓摩擦型连接,翼缘和腹板全部拼接。试验结果表明:螺栓拼接节点的延性远好于梁柱焊缝连接;较弱的拼接节点产生较大的塑性变形;接触面的滑移摩擦、螺栓与孔壁的挤压和翼缘拼接板的屈曲都使连接具有良好的耗能能力;但滑移伴随有剧烈的响声,会使人产生心理恐慌。根据试验结果提出了设计建议:尽量将拼接设计得弱些,可以提高梁柱连接的转动能力,减少地震作用向梁柱连接焊缝的输入,延缓焊缝的脆性破坏。     

扇形焊接开孔于钢骨梁柱接头耐震行为之影响

扇形焊接开孔为进行梁翼板全渗透开槽焊接时所需之工作孔。然而,实尺寸梁柱接头试验证实,传统梁腹板锁螺栓及梁翼板全渗透焊接之钢构造梁柱接头,常于扇形开孔处发生突然性之脆性破坏。本研究采用非线性有限元素分析方法,探讨扇形焊接开孔于钢骨梁柱接头耐震行为上之影响,包括扇形开孔几何形状对接头区力学行为之影响。分析结果显示,平顺接至梁翼板之扇形开孔能将最大塑性应变之发生位置移离扇形开孔根部,减少因几何形状不连续所造成之应力集中现象,降低局部区域之韧性需求;无扇形开孔之梁柱接头可避免有扇形开孔之缺陷,大幅的改善梁柱接头之韧性行为。     

The effect of stiffeners on the strain patterns of the welded connection zone

The behavior of the welded I-beams to box-columns connections is investigated both experimentally and numerically to identify the effects of stiffeners and column flange thickness on the energy dissipation characteristic of the connection. Numerical test specimens were developed and analyzed by the finite element method and the results were compared with full-scale experiments. The effects of various stiffeners such as, column stiffeners, side-stiffeners, and top-flange, and bottom-flange stiffeners were investigated. The contribution of each stiffener in controlling the location of the plastic deformation and the energy dissipation in the connection zone were examined.     

Experimental study on steel built‐up column moment connections with top and bottom trapezoidal side plates

Built‐up and box columns are used extensively in steel structures. A kind of built‐up column is composed of two I rolled shapes separated by calculated interval and welded between two cover plates. The uncertainties due to these columns are the flexibility of the column cover plates under the transferred beam flange plate forces and the brittle behavior of the groove weld between the beam flange plate and the column cover plate. The top and bottom trapezoidal side plates are proposed to improve the behavior of these column moment connections. Using this approach, the total beam flange forces transfer to the lateral sides of the column, parallel to the beam web, by means of top and bottom side plates. An experimental test is developed to study the behavior of the proposed connection under cyclic loading. The results indicate that the proposed connection has sufficient strength and ductility to apply in special moment frames. Also, the rehabilitated connection eliminates the vulnerabilities of deformation of the column cover plate and brittle fracture of groove welds in conventional connections. Copyright © 2016 John Wiley & Sons, Ltd.     

国家体育场桁架柱外柱节点设计研究

国家体育场桁架柱外柱节点的几何关系复杂,存在T型、K型及KT型等多种腹杆形式,腹杆侧壁与外柱壁板斜交,还存在与立面次结构相交的情况。焊接薄壁箱形构件相贯节点的刚度差,承载力低。本文通过在外柱内设置横向加劲肋与局部纵肋等构造做法,可以有效提高节点刚度与承载力。对于有次结构的外柱节点,次结构的上、下壁板不能全部贯通,在保证腹杆与外柱传力可靠的前提下,在外柱节点区设置传力三角区。对于K型腹杆节点,翼缘较厚的腹杆贯通;对于KT型腹杆节点,中间腹杆贯通。通过合理设计拼接焊缝位置、采用整板切割等方式,可以有效减少焊缝数量,避免焊缝重叠。采用有限元法分析外柱节点的受力形态,并根据“最大平均应力”的原则确定节点域板件的厚度,实现“强节点”的设计理念,保证节点的可靠性与经济性。     

3D simulation of bolted connections to unstiffened columns-I. T-stub connections

The paper presents a finite element methodology in a three-dimensional (3D) framework to study numerically the stiffness and strength of the T-stub to unstiffened column flange bolted connection as part of a comprehensive research program to investigate the behavior of endplate bolted connections. In such connections, the axes of rotation of the T-stem and column flange are at right angles; the planes containing the tensile forces are also perpendicular to each other. Therefore, they are highly interactive spatially. The main objective here is to study the applicability of the model to such a connection, so that most of the important features which are not accessible to routine experiments, like prying action and gradual plasticity of components, can be monitored. ANSYS, version 4.4, a large-scale general purpose finite element code is selected for this analysis. Initially, the simplest connection with the bolt groups in tension, which is a symmetric T-stub hanger with a single line of bolts parallel on each side of the web, is considered. Then the T-stub connection to an unstiffened column flange is discussed. Analytical results of a full-scale extended endplate connected to unstiffened column flange will be presented in Part II, a companion paper (Journal of Constructional Steel Research, 1996, 40, 189–223) in which the structural properties of such connections will be discussed.     

箱形柱芯筒式双法兰连接平面框架抗震性能试验研究

为解决施工现场闭口截面柱焊接难的问题,提出一种便于钢结构高效连接的箱形柱芯筒式双法兰连接及其在多遇、设防以及罕遇地震作用下的设计方法,依此设计了一榀5层原型结构,并对7:10缩尺的子结构进行拟动力和拟静力试验,研究结构的滞回性能、各典型部位应变、刚度、法兰板滑移和螺栓拉力等受力性能.拟动力试验结果表明,结构在El Ce...     

The rigid seismic connection of continuous beams to column

This paper presents a new rigid connection with some specific features for earthquake-resistant steel structures. In common practice, beams are separately placed between two adjacent columns and connected to their flanges. In this new proposed connection, two beams pass next to the column faces without interruption and are connected to the column flanges by vertical plates. Two different details of this connection have been studied experimentally and analytically. In the first detail, two integrated vertical plates which are placed next to the column flanges and welded to the column flanges’ edges and beam flanges were used in order to connect the two channel-section beams to the column. In the second detail, four vertical trapezoidal plates which are welded to the edges of the column flanges and beam flanges were used in order to connect the two I-section beams to the column. Two experimental specimens for each of the two different details were tested under cyclic loading. Experimental results show that all experimented specimens sustained the interstory drift angle greater than 0.08 rad without any significant loss of strength, which is far in excess of the requirements for a beam-to-column connection given by the latest seismic codes. The experimental and analytical results show that moment capacity of these connections is more than bending resistance of connected beams. Therefore, the structural ductility in this structural system is controlled by the flexural behaviour of beam ends; and the total behaviour of connections and also of column might remain reasonably elastic. As a result, the structure might have high ductility and safe seismic behaviour. Parametric studies show that the design relationships of connection plates safely determine the thickness of connection plates for different sizes of beams and columns.     

基于等效结构应力的钢框架焊接梁柱节点低周疲劳评估

在地震作用下钢框架梁柱焊接节点会发生低周疲劳现象,进而导致结构发生破坏。本文基于等效结构应力法提出一种高层钢框架梁柱焊接节点低周疲劳评估方法。首先,结合有限元多尺度模拟方法,建立包含翼缘及腹板焊缝细节的钢框架梁柱焊接节点多尺度模型。其次,利用不同单元尺寸多尺度模型,验证结构应力的网格不敏感特性,进而通过等效结构应力法评估钢框架梁柱焊接节点的疲劳寿命。结果表明,采用等效结构应力法可消除网格的敏感性,在往复荷载作用下,靠近工艺孔焊缝应力水平高于远离工艺孔焊缝,翼缘中心焊缝寿命最低,裂纹最先产生于翼缘焊缝中心处,评估方法为实际工程提供技术支持。