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.     

Seismic design of reduced beam section steel moment connections with bolted web attachment

Recent test results on reduced beam section (RBS) steel moment connections showed that specimens with a bolted web connection tend to perform poorly due to premature brittle fracture of the beam flange at the weld access hole. The measured strain data appeared to indicate that a higher incidence of base metal fracture in bolted web specimens is related, at least in part, to the increased demand on the beam flanges due to the web bolt slippage and the actual load transfer mechanism which is significantly different from that usually assumed in connection design. In this paper, the practice of providing web bolts uniformly along the beam depth was brought into question. A new seismic design procedure, which is more consistent with the actual load path identified from analytical and experimental studies, is proposed. A pilot test specimen designed by following the proposed procedure exhibited sufficient cyclic connection rotation capacity without fracture.     

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。     

装配式钢筋混凝土柱-钢梁框架节点抗震性能试验研究

通过4个1/2比例装配式钢筋混凝土柱 钢梁框架节点低周往复荷载作用下的试验研究,分析了节点区加劲腹板厚度及开孔的影响,研究该新型节点连接构造的受力性能及装配式钢筋混凝土柱 钢梁框架单元的抗震性能。基于试验结果对试件的破坏特征、滞回性能及变形组成进行分析。研究结果表明：装配式钢筋混凝土柱 钢梁框架节点滞回曲线呈纺锤形,梁端塑性铰区充分耗散能量,具有良好的抗震性能;装配式螺栓连接钢筋混凝土柱 钢梁混合节点具有良好的连接质量;加劲腹板厚度的增加一定程度上减小了节点的剪切变形,加劲腹板开孔对节点受力性能影响不大;梁弯曲变形引起的层间侧移在强柱弱梁型钢筋混凝土柱-钢梁框架节点总侧移中所占比例最大,节点剪切变形所占比例较小。     

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。     

Panel zone evaluation of direct connection to box column subjected to bidirectional loading

As an effective factor for force‐controlled components, in special moment frames, the main advantage of using box column is high biaxial bending strength. Most research studies have been concentrated on the box column performance subjected to unidirectional loading. On the other hand, seismic provisions given so far in codes are limited to beam to wide flange column connections with planar webs. In the research work presented, the bidirectional loading configurations are adopted to better simulate the actual response of the box column subjected to a ground motion excitation. The connection used in the article is welded unreinforced flange–welded web, being the direct connection that was introduced in the American Institute of Steel Construction as one of the prequalified connection. Analytical results from finite element method indicate that when the structure is subjected to bidirectional loading, the level of shear and flexural strength capacity of the box column reduces. Because of the yielding of the panel zone and the inner diaphragm, the distribution of stress and strain in the finite element models reveals that the design criteria presented in most seismic codes seem not to place the plastic hinge out of the panel zone region and therefore need to be modified. Copyright © 2013 John Wiley & Sons, Ltd.     

方钢管柱-H形梁栓焊混合连接节点抗连续性倒塌性能试验研究

以2个方钢管柱-H形梁内隔板式刚性连接节点试件为研究对象,采用双半跨单柱型梁柱子结构,通过静力加载试验研究梁柱节点在中柱失效的连续性倒塌条件下的力学性能。试件梁柱节点采用栓焊混合连接方式,2个试件的腹板分别采用不同的螺栓排列形式。结果表明,试件的破坏均出现在节点区,发生于梁弦转角达到0.06 rad之后。最不利梁截面破坏时,首先发生下翼缘断裂,采用螺栓单列布置的试件发生下排螺栓孔壁局部承压与冲剪顺序破坏,而采用螺栓双列布置的试件发生剪切板内列螺孔处净截面开裂。梁柱子结构在加载前期主要通过受弯机制提供竖向抗力,在加载后期逐渐转变为依靠悬索机制抵抗上部荷载,且悬索机制最终可提供的竖向抗力高于前期受弯机制提供的竖向抗力。与梁柱节点采用腹板螺栓中部集中布置形式相比,腹板螺栓沿梁高度分散布置更利于梁翼缘开裂后剩余截面发展轴向拉力,可提高悬索机制竖向抗力与节点鲁棒性。     

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。     

钢梁混凝土柱节点中梁贯穿与柱贯穿节点受力性能对比

通过钢梁与混凝土柱节点中梁贯穿节点与柱贯穿节点两组节点共6个试件低周反复荷载试验对比,分析了不同节点连接方式下节点开裂、极限荷载、位移、刚度、耗能能力等性能。结果表明,梁贯穿节点破坏主要发生在钢梁根部翼缘及腹板,而柱贯穿节点的破坏主要发生在钢梁与锚板间的焊缝处,由于核芯区有腹板和翼缘穿过,梁贯穿节点在受力性能方面优于柱贯穿节点。梁贯穿节点的抗震能力略大于普通混凝土节点,柱贯穿节点与普通混凝土节点抗震能力对比有待于进一步研究。     

内置薄壁H形钢-木组合梁受弯性能研究

为实现钢材与木材的高效组合,提高钢木组合梁受弯性能,提出了一种内置薄壁H形钢-木组合梁。为研究其破坏过程、破坏形态及组合受力性能,以翼缘木板宽度、抗剪连接栓钉间距、薄壁H形钢厚度、翼缘木板厚度、腹板木板高度和腹板木板厚度等为变化参数开展了受弯试验。并提出了可用于预测内置薄壁H形钢-木组合梁挠度和受弯承载力的计算公式,进行了有限元分析。结果表明：依据内置薄壁H形钢-木组合梁破坏过程及特征,可出现受拉翼缘木板受拉断裂、腹板木板受拉区开裂以及受压翼缘木板受压破坏或薄壁H形钢受压翼缘严重压屈和严重粘胶剥离的受压破坏三种破坏模式;在配置截面面积比约3.5%的薄壁H形钢的情况下,内置薄壁H形钢-木组合梁的受弯承载力、抗弯刚度、耗能和延性相对于纯木梁明显提高;腹板木板高度、翼缘木板宽度、翼缘木板厚度和抗剪连接栓钉间距等参数影响内置薄壁H形钢-木组合梁受弯性能较为明显,增加腹板木板的高度、翼缘木板的宽度、翼缘木板的厚度和减小抗剪栓钉间距可明显提高内置薄壁H形钢-木组合梁的受弯承载力;增加薄壁H形钢厚度,可使内置薄壁H形钢-木组合梁受弯承载力和刚度得到一定程度的提高;腹板木板的厚度对内置薄壁H形钢-木组合梁的受弯承载力影响不甚明显。所提出内置薄壁H形钢-木组合梁的挠度及受弯承载力计算式和有限元模型合理有效,计算结果与试验结果吻合良好。     

足尺钢梁柱刚性连接节点抗震性能试验研究

通过10个不同连接构造的足尺钢梁柱刚性连接节点的试验,研究了标准栓焊连接节点、标准全焊连接节点、梁翼缘加强型节点、梁翼缘局部削弱型节点以及梁贯通型节点在梁端往复荷载作用下的破坏过程、破坏形态、承载力和塑性变形能力等抗震性能。试验结果表明,梁翼缘局部切割削弱和梁翼缘加盖板节点的梁的极限塑性转角大于0.03,梁贯通型节点、梁下翼缘加腋节点和梁翼缘打孔节点的梁的极限塑性转角大于0.02,其余类型节点的都小于0.02。对实测的梁翼缘和腹板的应力分布的分析表明,梁根部翼缘处于三向应力状态,是其脆性断裂破坏的原因之一。建议钢框架梁柱连接优先采用梁翼缘加梯形盖板节点和梁下翼缘加腋节点。     

Mechanical performance of T-stub connections between square concrete filled steel tubular column and steel beam

传统的钢管混凝土柱-钢梁T形件节点易出现柱或者钢梁损伤严重的情况,不利于震后快速修复。以常规T形件和设置长槽孔T形件作为耗能构件,保证柱和梁损伤较小甚至不受损伤,实现耗能构件的可替换。对3个常规T形件节点和2个设置长槽孔T形件节点进行了数值模拟,分析了T形件翼缘厚度、T形件翼缘及腹板宽度、下T形件设置长槽孔、单边抗剪角钢等因素对节点滞回曲线、初始刚度、极限转角、延性系数、耗能能力的影响。研究结果表明：节点整体耗能较好,设置长槽孔T形件节点可显著提高节点延性,增加抗剪角钢的长槽孔T形件节点可显著提高节点耗能能力,该类节点滞回曲线呈饱满梭形,耗能表现为摩擦耗能和T形件塑性变形耗能共同作用;对于常规T形件节点,建议T形件翼缘厚度与腹板厚度的比值小于2.0。     

Experimental study on steel beam–columns composed of slender H-sections under cyclic bending

This paper presents an experimental study of six H-section steel beam–columns with large width-to-thickness ratios subjected to combined constant axial force and cyclic bending moment about the strong-axis. Considering different categories of cross-sections, various width-to-thickness ratios of the flange and web of the specimens were selected, and a reliable structural testing system was employed. The test results showed that, for all the specimens, local buckling was the dominating failure mode. Due to their relatively large width-to-thickness ratios of the flange and web, the H-section specimens exhibited limited resisting strength but certain plastic deformation capacity as well as energy dissipation capacity, encouraging employment of such members in seismic areas. It was also found that the flange width-to-thickness ratio and the axial force ratio have significant effects on the hysteretic behavior. In addition, a modified plastic effective width method for ultimate strength was proposed.     

钢结构焊接翼缘板加强式梁柱刚性连接滞回性能试验研究

焊接翼缘板加强式梁柱刚性连接是塑性铰外移以提高连接塑性变形的一种改进形式。为考察这种连接形式在循环荷载作用下的滞回性能,共进行了4个1/2模型的拟静力加载试验,研究了梁翼缘宽厚比、腹板高厚比对连接性能的影响和节点域强弱对连接塑性转动能力的影响。作为比较,还进行了一个盖板加强式梁柱刚性连接的试验。试验结果表明,这种连接形式性能优良,所有的试件都没有发生脆性破坏,都能确保塑性铰转移到加强板以外,梁端塑性转角介于0.044～0.054rad之间,达到了特殊抗弯钢框架连接塑性转动能力不小于0.03rad的要求。在试验过程中所有的加强板都没有发生局部屈曲。在满足我国抗震规范要求的前提下,增大梁翼缘的宽厚比,梁翼缘更易于发生塑性局部屈曲,但对极限承载能力和变形能力的影响不大;减小梁腹板的高厚比则对承载能力的影响较明显;较弱的节点域,会显著降低连接的承载力,但可提高其变形能力。     

Local Flange Bending and Continuity Plate Requirements in Double-Web H-Shaped Columns

In steel moment frames, columns are subjected to unbalance moment that is transmitted into the joint through a couple of concentrated forces at the centroid of the beam’s flanges. If the flexural capacity of the column flange is less than produced moment by these tensile or compressive forces, use of continuity plates in the panel zone is necessary. Since in box-shaped column, welding the forth edge of a continuity plate to the column flange may not be easily done and is usually accompanied by remarkable difficulties, double-web H-shaped columns as an appropriate alternative, which often do not require continuity plates, can be used. Numerous studies are carried out on local flange bending in H–shaped columns and are referred in the valid guidelines. The behavior of double-web column’s flange is between box shaped and H-shaped column’s flange. This paper presents analytical and numerical modeling of double web column to estimate local flange bending. The numerical modeling is derived from the results of finite element analyses. Based on these two approaches, some equations are presented to estimate local flange bending of double web columns, and are shown their efficiency and accuracy.     

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.     

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.     

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。     

腹板双角钢梁柱连接循环荷载试验研究

为了研究腹板双角钢梁柱连接的抗震性能,对四个连接试件进行了梁端循环位移加载试验。试验中考察了角钢高度、角钢与柱翼缘连接高强螺栓的直径和排列布置对连接的承载能力、滞回性能和破坏机理的影响,分析了这种连接的破坏模式和变形能力。试验结果表明:连接在循环荷载作用下表现出良好的延性,转角均超过0.04rad,连接的最终破坏均为角钢的塑性撕裂破坏;连接具有相当的抗弯能力,在结构分析中,须考虑节点抗弯强度对框架性能的影响,不能简单作为铰接处理;增大角钢的高度,能提高连接的强度;增大螺栓间距,减小螺栓直径,能提高连接的延性。最后,根据试验结果提出设计施工建议。     

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。