密肋框格防屈曲低屈服点钢板剪力墙抗震性能试验研究

密肋框格防屈曲低屈服点钢板剪力墙是一种新型抗侧力体系,采用力学性能优良的低屈服点钢作为内填墙板,通过密肋框格抑制钢板面外屈曲。为 系统研究其抗震性能,进行了3榀1/3比例单跨两层半试件的低周往复荷载试验。对比分析各试件在循环荷载作用下的承载力、延性、刚度和耗能能力,探究 不同节点刚度和框-墙连接方式的影响,考察三者的破坏形态。试验结果表明：密肋框格防屈曲钢板墙具有稳定的承载力和良好的塑性变形能力,结构初始 侧向刚度大,耗能性能优良。防屈曲密肋框格的设置起到类似两边连接的作用,有效改善了内填板的受力特性,试件的滞回曲线饱满,避免出现“捏缩”现 象。结构具有理想的屈服顺序和较为合理的破坏模式。梁柱节点对试件的抗震性能影响较小,降低连接刚度能够提高结构的延性和耗能。最后将各试件承载 力和初始刚度的理论计算值与试验结果进行对比,二者较为吻合。     

Ultimate strength of gusset plate connections with fillet welds

Braced frames are commonly used as lateral-load resisting systems in seismic design. The braces are connected to the beams and columns by gusset plate connections. Fillet welds are commonly used to connect the gusset plates to the beams and columns. And the fracture of the interface welds were observed in the past research and earthquakes. This paper focused on the ultimate strength of interface weld connection between gusset plate and frame elements when the brace is in tension. Pilot experimental study was conducted with four specimens and proved that the evaluation recommended by AIJ works well. A verified finite element analysis model was developed to conduct a parametric study. The studied parameters are the brace angle, gusset plate size, and eccentricity of brace. From the parameter study, it is confirmed that the tensile brace axial force is primarily transferred to the interface weld within an extension Whitmore region, which is named as the effective region in the AIJ evaluation. And the extension Whitmore region is affected by the gusset plate geometrical constraint. A revised extension Whitmore region is suggested by considering the aforementioned parameters. The AIJ evaluation using the revised extension Whitmore region is also compared with the UFM, and showed better evaluation for the rectangular shape gusset plate.     

Behavior and design of gusset plate connections in compression

A total of thirteen full-scale tests were conducted to investigate the compressive behavior and strength of gusset plate connections. The test parameters included gusset plate thickness, size, and brace angle. In addition, the effects of frame action on the compressive behavior of gusset plate connections were also investigated. In general, the gusset plate specimens were failed by sway buckling of the connection since no out-of-plane restraint was provided from the bracing member. The test results indicated that, in general, significant yielding of the gusset plate specimens occurred prior to reaching the ultimate load. However, only limited yielding was observed for the thin specimens with a plate thickness of 6.5 mm. The ultimate load of the specimens increased almost linearly proportional to the gusset plate thickness and decreased with increasing plate size. A slight decrease in the ultimate load of the specimens was observed when a 30° brace angle was used instead of a 45° one. The beam and column moment had only negligible effects on the ultimate load of the specimens; however, yielding of the specimens was detected at a load level significantly lower than that had no framing moment. The numerical simulation provided good agreement with the test results.     

管板连接轴心受拉构件极限承载力试验研究

对6个管板连接构件进行了受拉极限承载力试验研究和有限元分析。试验表明,试件的破坏均为长槽孔末端钢管横截面被拉断,其中,用板补强的试件GPT-3和GPT-6在破坏前钢管出现了明显的颈缩。分析表明,试验结果和有限元分析结果吻合良好,现行美国规范(ANSI/AISC 360-05)和加拿大规范(CAN/CSA-S16-01)中未补强的管板连接受拉承载力设计公式安全适用。研究表明,管板连接构件在受拉过程中,剪切滞后现象非常严重;长槽孔末端绕焊的焊缝质量对构件的受拉极限承载力有很大的影响。     

管板连接轴心受压构件极限承载力试验研究

对5个管板连接构件进行了受压极限承载力试验研究和非线性有限元分析。试验表明,未补强的试件GPC-1,GPC-3和用钢板补强的试件GPC-4,GPC-5的破坏模式均为试件的整体失稳,用焊接空心球补强的试件GPC-2的破坏模式为钢管的局部屈曲。试验结果与有限元计算结果基本吻合。实际工程中应用管板连接构件作为受压构件时,必须加强构件弱轴的刚度,以避免整体失稳破坏,而采用焊接空心球补强是一种有效的方法。     

Behaviour of steel cap plate connections: Experimental tests

This paper reports the results of a study conducted to investigate the behaviour of steel cap plate connections. In the analysis and design, connections are characterized as either rigid or pinned and between these two extremities lies the actual behaviour of steel frame connections, which is semi-rigid. This classification is characterized by the nonlinear moment-rotation relationship which must be incorporated in the analysis. A cap plate connection is widely used in industrial steel frames for its advantages over other types of building connections, but the response of such a connection has not sufficiently been experimentally determined. In this research, the behaviour of cap plate connections was studied by testing four full-scale connections. Experimental results obtained would add valuable information to the available test data concerning steel connections since sparse data is available in the literature for this type of connection. Mathematical and numerical models were used to analyze the cap plate connection and close correlations were found between these models and the experimental results.     

铝合金扣板燃烧性能的试验研究

从建筑装修材料使用发展的现状出发,对铝合金扣板材料进行多项燃烧性能试验.结合建筑内部装修设计的防火性能要求,分析铝合金扣板材料的适用性,取得了规范未明确规定但又能符合实际防火性能要求的认识和意见.     

基于滑移连接的防屈曲支撑钢框架节点抗震性能研究

防屈曲支撑（BRB）是一种拉压均可全截面屈服耗能而不屈曲的金属阻尼器,在建筑结构的抗震减震设计中得到广泛应用。然而,由于大变形下支撑框架节点存在显著开合效应,在罕遇地震作用下易出现节点板和相邻梁柱构件的提早断裂现象,限制了BRB抗震性能的充分发挥。为此,在总结BRB钢框架节点的现行设计方法及节点失效模式基础上,提出了可释放节点开合效应的滑移连接节点板,采用低摩擦材料减小接触面摩擦力。建立有限元模型,通过与传统焊接节点板对比,分析两种不同连接对节点板、梁柱和BRB受力性能的影响。以此为基础,设计该类节点足尺试验模型,对其进行拟静力试验,分析其在往复荷载下的抗震性能。研究结果表明：所提出的滑移连接可有效释放节点板与梁柱之间的切向约束和开合效应,显著降低了节点板的塑性损伤,实现了罕遇地震作用下节点板弹性的性能目标;梁塑性铰由节点板端部移至梁柱交界面处,降低了梁柱构件的剪力水平和塑性损伤;在层间位移角4%下各关键构件仍具有饱满稳定的滞回性能,显著提高了BRB钢框架的抗震性能。     

防屈曲支撑角部节点板与钢框架的相互作用效应

防屈曲支撑是一种高效稳定的耗能减震装置,其与框架结构一般通过焊接节点板形式连接。目前节点板连接设计方法仅考虑支撑轴力的影响,并没有直接考虑框架开合效应(梁柱在水平地震力下产生的张开/闭合变形)的不利作用,导致焊接节点板在连接处提前发生开裂。通过有限元模拟的方法,同时考虑开合效应和支撑轴力的共同影响,对防屈曲支撑钢框架与角部节点板连接的相互作用进行研究。有限元模型共5组,主要参数包括节点板尺寸、节点板与框架的连接形式以及节点板是否设置自由边加劲肋。在连接形式方面,提出了一种可减小开合效应不利影响的新型可滑移螺栓连接节点板,并与传统焊接节点板的受力性能进行比较。分析结果表明,平面尺寸较小的焊接节点板对结构的抗侧刚度影响最小,可减小设置防屈曲支撑的子框架所分担的地震剪力,相应的节点板受力性能也优于平面尺寸较大的焊接节点板|在焊接节点板上设置自由边加劲肋并不能明显改善其受力性能|所提出的新型可滑移螺栓连接节点板可有效减小节点板对结构刚度的影响,以及框架开合效应对节点板的不利影响,是一种在消能钢框架支撑体系中具有应用前景的新型节点板连接。     

Cyclic behavior of low yield point steel shear walls

This paper presents the research works on the cyclic behavior of low yield point (LYP) steel shear wall. In the LYP steel shear wall system, the LYP steel plate is used for steel panel and conventional structural steel is used for boundary frame. A series of experimental studies were carried out to examine the stiffness, strength, deformation capacity, and energy dissipation capacity of the LYP steel shear wall under cyclic load. The effect of width-to-thickness ratio of steel plate, continuity of shear wall, and the design of beam-to-column connections on the boundary frame was examined. Good energy dissipation capacities were obtained for all specimens studied. Excellent deformation capacities were obtained from both rigid frame–shear wall system and simple frame–shear wall system. The LYP steel shear wall is able to maintain stable up to 3–6% of story drift angle. A two-force strip model was also proposed to simulate the elastic and inelastic behavior of shear wall system. Good correlations were found between experimental and analytical studies. Based on these research findings, suggestions are made for the design of LYP steel shear wall systems.     

Constitutive behavior of low yield point steel LYP160

为了研究低屈服点钢材LYP160的本构行为并提出循环本构模型,进行了此种钢材的循环加载试验,研究其受力性能,包括单调受力性能、滞回性能、破坏模态及耗能能力等。利用Ramberg-Osgood模型,得到材料骨架曲线。采用Chaboche模型,确定了循环本构模型的关键参数,利用此模型预测低屈服点钢板剪力墙结构的滞回行为。结果表明：低屈服点钢材LYP160虽然初始屈服点低,但其抗震性能较好,延性约为普通钢材及高强度钢材的2.3~2.8倍;能量耗散系数在3.6左右,耗能能力明显高于普通钢材和高强度钢材,提高幅度约30%,LYP160钢材具有显著的单调及循环强化性能,具有较高的承载能力,其滞回特性包含了各向同性强化与随动强化两种特征,其中各向同性强化行为具有控制作用,这与普通钢材及高强度钢材有明显的区别。     

Compressive behavior of central gusset plate connections for a buckling-restrained braced frame

Buckling-restrained braced frames (BRBFs) are used as lateral-load resisting systems in seismic design. The braces in BRBFs are connected to beams and columns by gusset plate connections, and can yield in both tension and compression instead of buckling. Although tests of buckling-restrained braces (BRBs) have demonstrated their ability to withstand significant inelastic axial deformation, large-scale BRBF tests have exhibited central gusset plate buckling before BRBs develop the ultimate compressive strength. To extend and better understand the experimental work, this paper presents an analytical study of the compressive behavior for BRBF central gusset plate connections using the finite element computer program ABAQUS. A model of a previously tested BRBF is conducted to predict experimental buckling load of the central gusset plate and verify the accuracy of a simple model of a central gusset plate connection including a beam and part of the BRB. The out-of-plane deformation of the central gusset plate resembles the buckled shape of a gusset plate with low bending rigidity provided by the BRB end. The experimental buckling load of the central gusset plate cannot be predicted based on the AISC-LRFD approach with an effective column length factor of 1.2. Therefore, a parametric study on the compressive strength of BRBF central gusset plate connections is conducted with various gusset plate dimensions and free-edge stiffeners. An inelastic plate buckling equation together with coefficient charts is proposed to predict ultimate load. For gusset plates with sufficient free-edge stiffener rigidity, the yield load can be developed and increased to the post-yield strength level. A required free-edge stiffener size is also recommended for BRBF central gusset plates to develop compressive yield load.     

带可更换低屈服点耗能梁段-端板连接的#br# 钢框筒结构抗震性能试验研究

为研究带可更换低屈服点耗能梁段 端板连接的钢框筒结构(SFTS-RSLs)抗震性能和震后可更换能力,以耗能梁段长度和楼板组合效应为研究变量,设计3个2/3缩尺的单层单跨SFTS-RSLs子结构平面试件。框筒柱和裙梁采用Q460高强钢,耗能梁段采用低屈服点钢LYP225。通过水平低周往复加载试验对结构的破坏模式、刚度、承载力、耗能能力、延性、可更换能力以及耗能梁段塑性转角与超强系数进行研究。试验结果表明：试件滞回曲线饱满,延性高,具有稳定、良好的耗能能力和塑性变形能力;耗能梁段的破坏模式主要为翼缘严重屈曲且翼缘 端板焊缝撕裂或腹板撕裂;耗能梁段超强系数均值约为1.95,极限塑性转角超过0.18rad,远大于AISC 341-16规定的塑性转角限值0.08rad;楼板组合效应对结构承载力、耗能能力、延性、可更换能力、耗能梁段塑性转角和超强系数影响不大,对结构的弹性刚度影响显著;减小耗能梁段长度能够提高结构承载力、抗侧刚度、耗能梁段塑性转角和超强系数,但会降低结构的耗能能力和延性;加载过程中,结构的塑性变形与损伤集中在耗能梁段,框筒柱和裙梁处于弹性状态,有利于结构震后修复与正常使用功能的快速恢复。     

Cyclic behavior studies on I-section inverted V-braces and their gusset plate connections

Inverted V-braces and their central gusset plate connections are popular patterns of brace arrangements for special concentrically braced frames (SCBF). To improve the understanding of their seismic performances and promote their applications in seismic designs, the hysteretic behavior of nine I-section inverted V-braces and their gusset plate connections subject to inelastic cyclic loading is examined through experiments and analytical simulations. It is found that the clearance at the brace end on the gusset plate, the locations of the intersection point of bracing members, and the ratio of the free edge length to the gusset plate thickness are the key parameters. The loading capacities of braced frames show no decrease before the brace low-cycle fatigue fracture, but a longer plateau at a lower load level exists in the hysteretic loops. Although specimens with a linear clearance exhibit better seismic behaviors, a negative clearance is also acceptable as long as the gusset plate does not fracture prior to the braces. A brace intersection point with moderate eccentricity is preferable for its better behavior and its economical dimension of the gusset plate, but the brace point location in the gusset plate could induce out-of-plane deformations in the gusset plate and cause the system ductility to deteriorate. Based upon test results, a suggested limitation of the ratio of the free edge length to thickness for the gusset plates is presented.     

Experimental study on low cycle fatigue strength of beam-to-column connections in steel bridge bents with different plate assembling and material mismatching

This study examined the effects of inherent defects due to plate assembling and material mismatched condition between base and weld metal on the fatigue strength of beam-to-column connections. Low cycle fatigue tests were carried out on specimens with different plate assembling systems and material mismatched conditions. The test results revealed that the global load-displacement relationships from specimens with different plate assembling systems and material mismatched conditions are similar, meaning these effects involve only local behavior of specimens. However, the fatigue strength of the specimens strongly depends on the location of defects resulting from plate assembling and mismatched conditions. The specimen with the undermatched conditions and the existing defect located closer to the corner of beam-to-column connection tends to have lower fatigue strength. The fracture surfaces indicated that failure patterns of specimen are different regarding mismatched conditions. While the crack propagated through the weld metal for the undermatched condition, it propagated towards the boundary between base and weld metal for overmatched condition. Elasto-plastic shell analysis was performed under the same condition as the experiments. And it is found that when evaluating fatigue strength of beam-to-column connections, the effects of plate assembling system and material mismatched condition should be considered.     

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。     

低屈服点钢RC框架抗震性能研究

通过2榀低屈服点钢筋和1榀普通钢筋的两层两跨RC框架低周反复加载试验,对结构的破坏形态、破坏机制、滞回曲线、骨架曲线、位移延性、刚度退化、耗能能力等抗震性能进行了较为深入系统的研究。研究表明,与普通RC框架相比,在相同水平承载力情况下,低屈服点钢筋RC框架具有延性性能好、变形能力大、刚度退化趋缓、耗能能力强的特性,可见,低屈服点钢筋RC框架具有更优的抗震性能。     

Fatigue strength of steel pipe-base plate connections

The comparative fatigue resistance of two types of steel light poles is investigated, both experimentally and analytically. The fatigue tests were performed on test specimens designed and proportioned by the California Department of Transportation. The constant amplitude fatigue behaviour wa was obtained at several levels of stress range. Exposed fatigue crack surfaces were studied theascertain the nature of the crack initiation and propagation. Theoretical fatigue life estimates were also made using an existing fracture mechanics model, thought to simulate the geometric condition represented by the wclded pipe-base plate connection. The fatigue resistance of the two series of specimens was much lower than originally anticipated. The fatigue resistance was found to be comparable to either category E or E', depending on the weld contact angle.