半刚性连接梁柱组合节点低周反复荷载试验研究

为研究半刚性连接梁柱组合节点的抗震性能,开展了1个纯钢框架梁柱中节点、2个组合框架梁柱中节点的低周反复荷载试验。梁柱采用平齐式高强螺栓端板连接,试验采用柱顶加载模式。对试件的试验现象、变形、应变和耗能能力等进行了分析和比较。试验结果表明,组合节点相对于纯钢节点而言,由于负弯矩作用下钢筋的抗拉作用和正弯矩作用下混凝土板的抗压作用,其受弯承载力和转动刚度均有较大程度地提高;连接弯矩-转角关系的滞回曲线饱满、稳定,具有良好的耗能能力;平端板连接梁柱组合节点在反复荷载作用下具有较高的承载力和良好的延性,抗震性能良好。     

圆钢管相贯节点滞回特性的实验研究

对两种几何特征的圆钢管空间相贯节点进行了静力单调和反复加载的实验研究,以作为进一步研究钢管桁架抗震性能的基础。设计了专用的加载装置以对试件中的杆件和节点施加较大内力。通过对4个试件的实验,得到了节点滞回特性曲线。研究揭示了这类节点塑性变形沿首次塑性开展方向累积的特点,并指出单调加载曲线可以基本包覆滞回曲线。实验表明,采用相贯节点的钢管结构,其滞回特性取决于节点的滞回行为。对给定节点在反复加载下的变形能力和耗能能力进行了量化评价。     

Hysteretic behaviour of flush end plate joints to concrete-filled steel tubular columns

The results of an experimental research study involving the testing of four bolted moment-resisting connections under simulated seismic loading conditions are presented. Each test specimen modeled the interior joint of a moment-resisting frame consisting of H-shaped steel beams and circular or square concrete-filled steel tube (CFST) columns using high-strength blind bolts. In order to investigate the seismic behaviour of the blind bolted flush end plate joints to CFST columns, the hysteretic performance, failure modes, stiffness degradation and energy dissipation of the connection type are evaluated in detail. The test parameters varied included the column section type and the thickness of the end plate. The experimental results indicate that both the blind bolted connections with circular and square sections exhibited excellent hysteretic behaviour in terms of their moment–rotation response, strain distributions and energy dissipation. Under cyclic loading, all tested specimens displayed large rotation ductility capacities, and the failure modes were similar to those under monotonic loads. The effects of cyclic loading on the behaviour of the composite joint were obvious, especially on load bearing and stiffness of the connections. The joint type exhibited excellent seismic performance, so that it can be effectively utilized in moment-resisting composite frame structures.     

多层钢框架半刚性端板连接的循环荷载试验研究

为研究多层钢框架半刚性梁柱端板连接的抗震性能,对8个不同构造端板连接足尺试件进行了循环荷载试验研究, 分析了端板厚度、螺栓直径、端板外伸加劲肋、柱腹板加劲肋、平齐式和外伸式等因素对节点承载力、转动刚度、极限转动 能力、耗能能力、延性和极限破坏状态的影响。试验结果表明,半刚性梁柱端板连接具有良好的延性和耗能能力,可以应用 于多层抗震钢框架中。根据试验结果及相关分析,提出了多层抗震钢框架中端板连接的标准构造为:两端外伸,设置柱腹 板加劲肋和三角形端板加劲肋,柱翼缘在端板外伸边缘上下各100mm范围内局部加厚,厚度与端板厚度相同。对提高端 板连接节点的抗震性能提出了宜采用大直径螺栓、中等厚度端板的设计建议。本文还在"强节点,弱构件"抗震设计一般原 则的基础上提出了"强连接,弱板件"的端板连接抗震设计概念。     

Seismic behaviour of beam-to-column partial-strength joints for steel-concrete composite frames

The paper presents a large experimental campaign carried out on ten steel-concrete composite beam-to-column sub-assemblages employing monotonic and cyclic loading test protocols. Structural members (beams, columns and slabs) were defined through the design of a full-scale 3D prototype frame subjected to PSD testing campaign; main design hypothesis was to dissipate seismic energy in the joints designed as partial-strength. Testing programme on beam-to-column sub-assemblages was executed in order to assess seismic performance varying structural details at beam-to-column connection level and material qualities. Different mechanical connecting systems between concrete slab and column, two end-plate configurations, weak and strong column web panel, two steel qualities and different concrete strengths.The analysis of sub-assemblages performance was realized in two steps: a first step in which the joints behaviour was assessed, characterizing response at local level (e.g. moment-rotation curves); a second step in which the response was assessed at global level (e.g. force-displacement curves). The structural behaviour (i.e. resistance, plastic deformation and stiffness) was evaluated at three stages-identified as initial, service and maximum load-in order to monitor the evolution of sub-assemblage response increasing solicitation level. Moreover, seismic behaviour of specimens-in terms of dissipated energy, ductility, over-strength and equivalent viscous damping-was also executed. Comparison between experimental results was made in order to identify those parameter suitable for improved and reliable seismic behaviour of steel-concrete composite partial-strength joints.     

外伸式端板连接蜂窝钢梁-混凝土柱组合节点抗震性能试验研究

通过7个1∶2比例外伸式端板连接蜂窝钢梁-混凝土柱组合节点的低周反复加载试验,研究不同螺栓数目、直径及排列方式的外伸式端板连接蜂窝钢梁-混凝土柱组合节点在各受力阶段的抗震性能和合理的节点构造形式。基于试验数据,分析了节点在反复荷载作用下的破坏形态、滞回曲线、骨架曲线、刚度退化、延性和耗能性能等。试验结果表明：试件的破坏形态和变形与螺栓数目、直径及排列方式有关,外伸端板螺栓连接中螺栓数目多、直径大的节点连接形式的承载力高,抗震性能较好;8个端板螺栓4行2列的排列形式为最合理的抗震节点形式;外伸端板螺栓数量为8个时的延性和耗能性能都能满足抗震的要求。     

Pipe damper,Part I: Experimental and analytical study

In this paper the behavior of steel pipes, filled and unfilled with concrete, is studied under cyclic shear to examine the possibility of their use as a seismic damper. Two specimens of steel pipes filled inside with concrete are tested under monotonic and cyclic shear. Four other specimens of bare steel pipes are tested under fully reversed cyclic shear loading. The results show that the bare steel pipes are capable of absorbing a great amount of energy under a severe cyclic shear loading with a stable hysteretic behavior. This behavior is also simulated using the finite element method. Then, parametric studies are performed to investigate the effects of variations in geometrical properties of the pipe on its hysteretic behavior. A simplified bi-linear model is proposed to approximate the hysteretic behavior of the steel pipe as a metallic-yielding damper.     

循环荷载作用下SN490B钢材本构关系试验研究

为对比结构消(耗)能元件芯材SN490B在单调和循环荷载作用下的本构关系,研究其在循环荷载作用下的力学特性,对20个SN490B钢材试件分别进行单调加载和16种加载制度下的循环加载试验,并对3种试件断口进行断口电镜扫描试验,分析SN490B钢材的单调性能、滞回性能和破坏形态,并采用Ramberg-Osgood模型拟合钢材的循环骨架曲线。试验结果表明：SN490B材料自身延性好,循环加载导致的材料累积损伤使其延性变差;循环荷载作用下,材料出现包辛格效应、循环硬化等现象,各滞回曲线均稳定饱满,具有较好的滞回性能;试件试验段伴随明显塑性变形而形成断口,断口微观为有微孔的波纹断裂表面,属延性破坏;应用Ramberg-Osgood模型拟合效果较好。SN490B钢材在循环荷载作用下的本构关系不同于单调荷载作用,采用单调荷载作用下材料的本构关系计算循环荷载作用下材料的反应不够准确。     

Q690高强钢外伸端板加劲螺栓连接节点抗震性能试验研究

为研究高强钢外伸端板加劲螺栓连接节点的抗震性能和设计方法,基于EC3规范组件法和同步塑性设计理念,设计了3种不同屈服机制的Q690高强钢外伸端板加劲螺栓连接节点,通过循环加载试验研究了节点的破坏模式、刚度和承载力、耗能能力以及应变分布规律等,进一步验证了节点能力设计计算模型的有效性.研究结果表明:高强钢外伸端板加劲螺栓...     

Performance of CFTST column to steel beam joints with blind bolts under cyclic loading

The objective of this research is to investigate the seismic performance of the composite joint consisting of square concrete filled thin-walled steel tubular (CFTST) column and steel beam with end plate and blind bolts. The cold-formed square tube in each CFTST column connection was fabricated by seam welding together four pieces of lipped angle with nominal wall thickness 1.5 mm or 3 mm. Four exterior joint specimens were tested under axially compressive load on the top of the columns and cyclic loads on the beam tip. The experimental parameters in the study were the thickness of the steel tube and the type of end plate. The seismic response of the blind bolted moment joints to CFTST columns was analyzed and evaluated in terms of the hysteretic behavior, failure modes, stiffness and strength degradation, ductility, and energy dissipation capacities of the joints. To improve the tension behavior of the blind bolted moment connections to the thin tube wall, the anchorage action of reinforcing rebar welded to the bolts with concrete-filled steel tubes was also investigated to consider the effect of cyclic loading. The experimental and analytical results indicated that when the end plate thickness is not less than 3 mm, the flush or extended end plate joints to CFTST columns exhibited large hysteretic loops and excellent seismic performance, such as ductility and energy dissipation capacity. The proposed innovative blind bolted joint was verified as a reliable and effective solution applied in mid- and low-rise buildings through properly design and detailing.     

不锈钢端板连接梁柱节点静力承载性能试验研究

为了研究不锈钢端板连接梁柱节点的静力承载性能,对5个不锈钢端板连接梁柱节点和1个普通钢端板连接梁柱节点开展单调静力加载试验,得到了节点试件的弯矩-转角曲线,对比分析了钢材牌号、节点类型和端板有无加劲肋等因素对节点承载性能的影响。结果表明：相同尺寸和构造的不锈钢节点延性优于普通钢节点的延性;不锈钢中柱节点和边柱节点的承载力相差较小,但前者的初始转动刚度较高而后者的变形更大;端板加劲肋的设置显著提高了节点的承载性能。基于得到的试验结果,对中国GB 51022—2015、美国ANSI/AISC 358-16和欧洲EN 1993-1-8中的端板连接节点承载性能计算方法进行评估,3种计算方法均低估了不锈钢端板连接梁柱节点的承载性能。     

胶合木梁柱角钢混合连接静力与抗震性能试验研究

为解决传统的木结构销栓连接刚度低、震后可恢复功能弱等问题,将钢结构梁柱翼缘角钢连接方法应用于木结构,提出了一种胶合木梁柱角钢混合连接形式。为研究此类木结构节点的静力与抗震性能,对节点试件进行了单调与低周反复荷载试验。研究结果表明：当梁柱截面尺寸分别为135mm×420mm和150mm×350mm,连接角钢规格为∟180×110×12时,胶合木梁柱角钢混合连接的极限弯矩达到95.3kN·m,最大转角接近0.096rad,初始刚度达4073kN·m/rad。低周反复荷载作用下,混合连接的变形能力与延性良好,梁端弯矩-转角滞回曲线呈反“S”形,角钢屈服后的大变形使其短肢底部与柱面产生了明显的分离,滞回曲线出现捏缩效应;角钢的短肢翘曲严重,从而使混合连接的耗能能力和等效黏滞阻尼系数均下降。     

穿斗式木结构通榫节点抗震性能研究及#br# 数值模拟分析

为研究穿斗式木结构通榫节点的抗震性能,对通榫节点缩尺模型进行低周往复荷载试验,分析节点的弯矩-转角滞回曲线及其骨架曲线、刚度退化规律、变形与耗能能力。采用ABAQUS非线性有限元软件对通榫节点进行数值分析,所得模拟结果与试验结果吻合较好。研究结果表明：通榫节点弯矩-转角滞回曲线捏缩效应明显,且随枋截面高度的增加而愈加明显;在加载过程中,枋在柱卯口处发生滑移,且滑移量随转角的增大而增大;节点的等效黏滞阻尼系数随着枋截面高度的增大而减小;通榫节点具有较好的延性和较大的承载力,加载转角达到0.22rad时,枋出现较大的挤压塑性变形,但未发生材料破坏。枋横纹应力达到其抗压强度,而柱顺纹应力尚未达到其极限抗压强度。     

Influence of asperity degradation on the mechanical behavior of rough rock joints under cyclic shear loading

A cyclic shear testing system was established to investigate the mechanical behavior of rough rock joints under cyclic loading conditions. Laboratory cyclic shear tests were conducted for two joint types of Hwangdeung granite and Yeosan marble: saw-cut and split tensile joints. Prior to test, the roughness of each specimen was characterized by measuring the surface topography using a laser profilometer. Several important aspects of cyclic joint behavior, such as high peak shear strength and non-linear dilation in the first loading cycle, different frictional resistance for the reversed shear loading direction, and anisotropic shear behavior and its dependence on the normal stress level were identified from the cyclic shear test results. These features and their variations in the subsequent loading cycles are mainly due to the effect of second order asperities and strength of rock material. It was also observed from experimental results that degradation of asperities under cyclic shear loading also followed the exponential degradation laws for asperity angle and the mechanism for asperity degradation would be different depending upon the shearing direction and the type of asperities. Based on the experimental results an elasto-plastic constitutive model, which can consider the degradation of second order asperities, was proposed. Numerical simulations for the monotonic and cyclic shear loading indicated agreement with the laboratory test results.     

Y形直接焊接矩形钢管节点滞回性能试验研究

对钢管结构中常用的Y形矩形钢管节点进行了试验研究。通过对支管施加轴向往复荷载,共对10个直接焊接Y形矩形管节点进行拟静力试验。为研究钢管加工及节点焊接过程中产生的残余应力对节点性能的影响,对其中2个节点进行了去应力退火处理。通过分析节点的承载力、延性比和能量耗散系数,对此种节点的滞回性能进行了深入研究。试验表明：在支管承受轴向往复荷载作用时,总是在支弦管连接焊缝外边缘沿支管侧壁方向切断弦管上壁面,从而导致节点性能的劣化。在弦管上壁面拉裂之前节点耗能性能良好,且退火节点在弦管上壁面拉裂之后仍然有较大的耗能潜力。节点的滞回性能较好,这为在抗震区推广使用管结构提供了有力支持。     

广府古建筑木结构箍头榫节点抗震性能研究

为研究广府古建筑木结构中广泛采用的箍头榫节点的抗震性能，以梁截面高度、柱直径、梁榫宽和柱顶轴压力为研究参数，设计制作了8个缩尺节点试件进行低周反复荷载试验，得到了不同研究参数下箍头榫节点试件的破坏形态、滞回曲线、骨架曲线、延性、承载力退化、刚度退化及能量耗散能力等。研究表明：各箍头榫节点试件转角达到0.1rad时，仍可维持稳定的承载状态，其承载力退化不明显，具有较好的承载性能以及良好的延性。试件的破坏形态包括柱内侧梁榫顶部(或底部)顺纹拉裂破坏、柱外侧梁榫竖向劈裂破坏和水平劈裂破坏；各节点的弯矩-转角滞回曲线均呈反Z形，且有明显的“捏缩”现象；在试验设计参数范围内，节点的转动刚度、极限弯矩和耗能能力均随着梁截面高度和柱直径的增大而增大，并随着梁榫宽的增大呈现出先增大后减小的趋势，一定范围内改变柱顶轴压力对试件抗震性能影响不大。采用有限元软件ABAQUS建立了箍头榫节点模型，并与试验进行了对比验证，结果表明该模型可较好地模拟反复荷载作用下的节点滞回性能。通过参数分析进一步研究了不同参数下箍头榫节点的弯矩-转角曲线，结果表明节点的屈服弯矩和极限弯矩基本与梁截面高度、柱直径大小呈线性正相关关系。     

Study of a new type of self‐centering beam‐column joint in steel frame structures

A new type of self‐centering beam‐column joint with installed steel arc plates is proposed in this study. First, mechanical behavior of the self‐centering joint using prestressed steel strands to provide the centering force is theoretically analyzed in detail, followed by experimental validation. New joints with different arc plate parameters are designed and tested under cyclic loading. Test results show that the hysteretic curve of the new joint exhibits typical characteristic of self‐centering capacity. By parametric analysis of five design parameters of the arc plate, it is found that vector height has the greatest influence on the joint's moment‐rotation skeleton curve, which is consistent with experimental findings. A simplified model of the joint is built in OpenSees to simulate its hysteretic behavior, which agrees well with the tested results. To demonstrate the effectiveness of the new joint to improve the seismic performance of the overall structure, a series of nonlinear time history analysis on a steel frame structure with the new joint under earthquakes are conducted, which show that the joint is particularly effective in reducing the residual interstory drift response.     

狗骨式型钢高强混凝土边节点抗震性能试验研究

为了研究狗骨式型钢高强混凝土(HSRC)框架边节点的抗震性能,对9个边节点试件进行低周反复荷载试验。试验结果表明:设计合理的狗骨式型钢高强混凝土框架边节点具有良好的位移延性和滞回特性;轴压比小的试件,其节点的滞回曲线较丰满,骨架曲线较平缓,延性与耗能能力相对较好;在轴压比相等或相近的情况下,对梁型钢采用狗骨式削弱的试件较普通试件具有更好的延性性能和耗能能力,位移延性系数提高幅度为10%～25%;对节点附近梁端型钢翼缘采取狗骨式削弱,能够将框架梁的塑性铰从梁端根部转移到削弱部位,从而有效地提高节点的抗震性能,达到延性设计的目的。     

高强钢芯筒-螺栓连接钢管柱框架节点抗震性能试验研究

为解决现有单边螺栓容易拔出、钢管柱壁板撕裂等锚固不足问题,提出高强钢板-螺栓组合连接副,用于钢管柱框架节点。为研究该类节点的抗震性能和破坏模式,设计4个足尺比例的高强钢芯筒-螺栓连接钢管柱框架节点试件,变化参数为螺栓规格和钢梁端板厚度,分别进行单调加载静力试验和循环加载拟静力试验,考察节点破坏模式、转动能力、连接系数、耗能能力及螺栓拉力。研究表明:M20-20、M24-25两种钢板螺栓组合连接节点可达到抗震规范的节点承载力连接系数限值要求,为半刚性节点;单调和循环两种加载方式下节点的破坏模式相近,节点域应变和变形都较小,对节点转动角度影响可以忽略;循环加载下节点的破坏位移明显较单调加载的小,梁端受弯承载力略有提高,芯筒端部钢管柱应变显著增长,M24-25节点的耗能能力较M20-20的高约10%;循环荷载作用下的螺栓最大实测拉力大于单调荷载作用下的螺栓最大拉力,组合连接副承载力的设计方法有待进一步研究。     

H形梁翼缘与端板非全熔透焊接的节点性能试验研究

对H形梁翼缘与端板分别采用全熔透焊接和非全熔透焊接的节点进行了对比试验。选择板件宽厚比、端板厚度、翼缘板与端板平面的夹角等设计参数,对24个试件进行了单调加载试验,6个试件进行了反复加载试验。试验结果表明:节点无一例发生焊缝破坏,焊缝形式对连接的最大荷载、翼缘近焊缝端应变以及滞回性能等无明显影响;在以局部屈曲为主要控制模式进行设计的轻型门式刚架中,无论对单调静力荷载还是反复荷载,H形梁翼缘与端板的连接都可采用非全熔透焊接。