方钢管覆板及竖向插板加强T形节点受压静力试验

为分析方钢管加强节点的轴压承载能力和破坏模式,对支管与主管宽度比β=0.4和β=0.8的两组覆板加强节点、竖向插板加强节点进行轴向静力加载试验。分析了节点破坏模式、荷载 位移曲线、主管变形及应变,以及加强节点的受压承载机理。结果表明：在支管轴向压力作用下,未加强及加强节点的变形能力都较好,试件在破坏前有充分的塑性发展;覆板及插板加强节点的受压承载能力较对应的未加强试件有显著提高,当β=0.4时加强节点的破坏模式与未加强节点一致,当β=0.8时存在节点过度加强问题,引起支管先于节点破坏;相同β下,覆板加强节点的受压承载力高于竖向插板加强节点;在主管表面屈服破坏控制的情况下,覆板加强节点的承载机理为覆板与主管上翼缘共同屈服,竖向插板加强节点的承载机理为插板扩大了主管上、下翼缘的屈服范围。     

轴压或轴向往复荷载作用下方钢管焊接T型节点的承载性能研究

采用试验实测的方法,研究不同支管与主管宽度比(β)的方钢管焊接T型节点的静力与滞回性能,分析了节点的破坏形态、荷载-位移曲线、承载及耗能能力。结果表明:支管与主管宽度比对节点的静、动力性能有明显影响,如在支管轴向压力作用下,β=0.4,0.8时试件的破坏分别受主管上翼缘屈服和主管侧壁屈曲控制,支管的轴向往复加载会引起节点的开裂破坏,试件裂纹分别沿主管上翼缘和支管根部贯通;β=0.4的试件能耗系数比β=0.8时提高43.5%,这种提高与各试件的耗能机制不同有关。往复加载试件的受拉开裂会降低节点的承载力,但按GB 50017—2003《钢结构设计规范》设计的节点承载力具有足够的安全储备。     

方钢管混凝土K型节点滞回性能试验研究

对1个方钢管K型节点试件和主管填充混凝土的6个K型方钢管节点试件进行拟静力试验,以研究支管尺寸、支管间隙等参数对方钢管混凝土K型节点破坏模式和延性的影响,并与K型方钢管节点试件进行对比。主管填充混凝土的K型方钢管节点的破坏模式包括支管与主管之间的焊缝破坏、支管受拉断裂、支管鼓曲以及主管撕裂;支管间隙较大的试件更容易出现主管撕裂破坏。主管填充混凝土后,其径向刚度显著提高,支管与主管连接处的应力集中程度也有所改善,节点的屈服荷载和峰值荷载有不同程度的提高,尤其是受压循环的峰值荷载提高幅值达到60%以上。主管填充混凝土后,K型方钢管节点试件的延性以及耗能系数都有所降低。     

L形包角环口板加强方钢管T形节点轴向滞回性能研究

为研究L形包角环口板加强方钢管T形节点（LCPT）轴向滞回性能,对一组包角环口板加强T形节点进行轴向往复加载试验,并与未加强（URT）和覆板加强节点（DPT）进行对比。结果表明：包角环口板加强节点的轴向滞回性能较优,LCPT试件比URT试件的最大荷载可提高103.2%;LCPT试件比DPT试件的累积耗能能力更好,且LCPT试件比DPT试件的拉压对等性更好。进一步对包角环口板尺寸和屈服强度进行有限元参数分析,结果表明：包角环口板厚度是影响LCPT节点轴向滞回性能的关键几何参数,提高包角环口板屈服强度可提高节点承载力,但对节点耗能能力几乎无影响。最后,对比覆板、环口板、包角环口板三种方钢管加强节点的承载和耗能机理,包角环口板加强节点的轴向滞回性能更优。     

主管壁加厚方钢管T型节点滞回性能研究

为了研究主管壁局部加厚对方钢管T型节点滞回性能的影响,对一个主管壁局部加厚的方钢管T型节点试件和一个主管壁未加厚的方钢管T型节点试件进行试验测试和有限元模拟。试验中,通过控制支管的竖向位移对方钢管T型节点试件施加低周往复循环荷载,研究试件的变形和破坏模式,并进行相关抗震性能指标（延性系数和能量耗散）分析。试验结果表明：主管壁局部加厚能够明显改善节点的滞回性能,同时能够使节点由带有明显延性特征的断裂破坏转变为主管壁厚改变处的延性屈服破坏。利用有限元软件ANSYS对试验试件进行有限元模拟,结果与试验结果吻合较好。最后利用有限元软件分析了主管壁加厚方钢管T型节点加厚参数（主管的加厚长度l和加厚厚度Δt）对节点滞回性能的影响。分析结果表明：为了改善节点滞回性能,加厚长度不超过支管截面边长的3倍,加厚厚度不超过主管壁厚的0.8倍。     

退火对Y形矩形钢管节点滞回性能影响的研究

为研究退火处理及几何参数对矩形管节点滞回性能的影响,对2组Y形矩形管-管节点及2组Y形纵向板-矩形管节点进行了拟静力试验。每组包含2个几何尺寸相同的试件,对其中一个进行去应力退火处理。将节点弦管底面中部固定,对支管施加轴向往复荷载。试验中裂缝在节点的弦管上表面出现,沿弦管与连接件(支管或节点板)的连接焊缝外围发展并穿透弦管壁,导致节点失效。节点的耗能机制为弦管上表面塑性变形。分析发现:退火导致节点的极限承载力减小,延性比、累积延性比、累积能量耗散比增大;随支弦管夹角增大,管-管节点极限承载力、累积延性比、累积能量耗散比减小;随节点板长度增加,板-管节点的极限承载力、累积延性比、累积能量耗散比增大。     

平面K形圆主管方支管节点承载力试验研究与有限元分析

对平面K形圆主管方支管节点的承载力进行试验研究,进行了5个空钢管节点和1个主管内灌混凝土节点的静力单调加载试验。介绍了节点试验方案,考察了节点的受力性能、破坏模式和承载力,给出了试件支管的变形曲线以及折算应变曲线,并对支管壁厚、主管内浇灌混凝土对节点承载力、刚度和延性的影响进行了分析。试验结果表明：现行国内外规范中圆钢管和方钢管节点承载力计算值明显低于试验值,已有的计算公式都不能准确计算圆主管方支管节点的承载力;增加支管壁厚改变了节点的破坏模式并明显提高了节点承载力和延性;主管内灌混凝土虽提高了承载力和初始刚度但延性并没有得到显著提高;圆主管方支管节点区域的变形主要源于受拉支管的局部变形。在节点破坏模式、变形曲线、承载力和塑性发展等方面将有限元计算值与试验结果进行比较,结果吻合良好,可以作为进一步分析的基础。     

中空夹层钢管混凝土-钢管K形搭接节点抗震性能试验研究

主管为中空夹层钢管混凝土，支管为空钢管的K形搭接节点，按主圆支圆和主方支圆两种形式加工制作了4个节点，对节点两个支管通过同步往复加载，研究主管通过夹层混凝土加强的K形节点破坏模式、承载力、耗能性能等。分析了试件的滞回曲线、骨架曲线、承载力、延性系数、能量耗散系数等抗震性能指标。结果表明：未加强节点的破坏模式为主管表面塑性破坏，主管夹层灌混凝土的加强节点为支管拉裂破坏；主管夹层灌混凝土提高了节点的刚度和承载力，对于方管尤为显著，但对节点的延性影响不大；相比主圆支圆的未加强试件，夹层灌普通混凝土和粉煤灰混凝土的试件承载力分别提高了43.7%和52.1%，节点累积耗能分别提高了57.6%和64.0%；相比主方支圆未加强试件，夹层灌普通混凝土和粉煤灰混凝土的试件承载力分别提高了66.7%和64.7%，节点累积耗能分别提高了39.8%和21.7%，但主管夹层灌普通混凝土和灌粉煤灰混凝土对节点的加强效果区别不大。利用ANSYS软件对试验试件进行有限元分析，分析结果与试验结果吻合良好，并选用主管空心率、支主管直径比及支管径厚比进行参数分析。分析表明：随主管空心率的增大，节点耗能能力和承载力有所减小；随支主管直径比的增大，节点滞回曲线趋于饱满，耗能能力和承载力提高；随支管径厚比的增加，节点的滞回曲线的饱满度降低，节点承载力和耗能能力均呈下降趋势。     

复式钢管混凝土外加强环板节点抗震性能试验研究

外加强环板节点构造简单、传力路径明确,是目前比较成熟且被广泛应用的钢管混凝土结构节点,针对复式钢管混凝土柱设计了其与H型钢梁连接的外加强环板节点,对9个复式钢管混凝土外环板节点试件和1个单钢管混凝土对比节点试件进行了低周往复荷载试验,以轴压比、外环板宽度、梁柱线刚度比以及锚固腹板是否加肋作为主要变化参数,研究了新型节点破坏形态、破坏机制、滞回曲线、骨架曲线、延性、耗能能力及强度刚度退化等性能。试验研究结果表明:梁柱线刚度比小的节点试件易形成梁端弯曲破坏形态,而梁柱线刚度比大易形成柱端压弯破坏形态;复式钢管混凝土外环板强度和刚度退化均匀、持续、稳定,表现出了良好的耗能能力和变形能力,抗震性能较好;轴压比增大可提高节点试件初始刚度;环板宽度增加可提高节点的延性;锚固腹板加肋可提高节点的承载力。     

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。     

Hysteretic performance of circular hollow section tubular joints with collar-plate reinforcement

Welded tubular joints have a weak stiffness in the chord radial direction due to the hollow section, and failure frequently occurs mostly on the chord surface along the weld toe. In the past, collar-plate has been proven to be effective in improving the stiffness and thus increasing the load carrying capacity of a tubular joint. This paper reports the results of a further study on investigating the effect of collar-plate reinforcement on the hysteretic behavior of a welded tubular joint. Overall, a total of 4 tubular T-joints with collar-plate reinforcement together with 4 corresponding un-reinforced specimens are studied experimentally. In the experimental tests, quasi-static axial cyclic loading is applied to these specimens. The hysteretic performance of the reinforced and un-reinforced T-joint specimens is then evaluated from the hysteretic curves, ductility and the energy dissipation ratio etc. Based on the experimental results, it is found that the T-joint specimens with collar-plate reinforcement can dissipate more energy before failure when they are subjected to cyclic loading compared to the un-reinforced ones, and thus they have a more ductile characteristic. Such ductility is attributed to the improved deformed capacity as well as the increased load carrying capacity of the reinforced T-joints.     

Hysteretic performance of circular hollow section tubular joints with collar-plate reinforcement

Welded tubular joints have a weak stiffness in the chord radial direction due to the hollow section, and failure frequently occurs mostly on the chord surface along the weld toe. In the past, collar-plate has been proven to be effective in improving the stiffness and thus increasing the load carrying capacity of a tubular joint. This paper reports the results of a further study on investigating the effect of collar-plate reinforcement on the hysteretic behavior of a welded tubular joint. Overall, a total of 4 tubular T-joints with collar-plate reinforcement together with 4 corresponding un-reinforced specimens are studied experimentally. In the experimental tests, quasi-static axial cyclic loading is applied to these specimens. The hysteretic performance of the reinforced and un-reinforced T-joint specimens is then evaluated from the hysteretic curves, ductility and the energy dissipation ratio etc. Based on the experimental results, it is found that the T-joint specimens with collar-plate reinforcement can dissipate more energy before failure when they are subjected to cyclic loading compared to the un-reinforced ones, and thus they have a more ductile characteristic. Such ductility is attributed to the improved deformed capacity as well as the increased load carrying capacity of the reinforced T-joints.     

Hysteretic behaviour of square tubular T-joints with chord reinforcement under axial cyclic loading

The stiffness of hollow section tubular joints is weak in the chord radial direction, and thus failure frequently occurs at the weld toe in the form of brittle fracture caused by crack propagation due to cyclic loading. To avoid such brittle failure, the chord at the intersection can be reinforced by increasing the chord thickness. With the chord reinforced, the failure position can be transferred to the chord intersection, and hence the cracking along the weld toe is prevented. To verify the efficiency of the proposed reinforcing method, both experimental test and finite element analysis are carried out on reinforced and un-reinforced square tubular T-joints subjected to quasi-static cyclic loads. The hysteretic curves, ductility ratio, energy dissipation and failure mode of the two full-scale specimens are studied experimentally, and it is found that the hysteretic curves of both specimens are plump, which show the T-joints can absorb much energy when they are subjected to seismic action. However, the enclosed area of the hysteretic curves of the reinforced T-joint is larger than that of the un-reinforced specimen because the chord reinforcement can prevent the fracture failure as well as improving the bearing capacity. The failure performance of the reinforced and un-reinforced specimens also show that a T-joint with chord reinforcement is more advantageous in resisting seismic action. Finally, the effect of the reinforced chord length and thickness on the hysteretic behaviour of square tubular T-joints is also investigated from a parametric study.     

Experimental Study on hysteretic behaviour of tubular N-joints

Tubular joints are often adopted in CHS structures due to their simple and aesthetic appearance. The ultimate load carrying capacity of this kind of joint has received lots of attention in the past 30 years. However, little research work has been carried out on their hysteretic behavior. In this paper, the hysteretic behaviour of tubular N-joints was studied experimentally. Four specimens were built and tested under quasi-static cyclic loads. They are unstiffened tubular N-joint, doubler plate reinforced tubular N-joint, tubular N-joint with concrete filled chord member and doubler plate reinforced tubular N-joint with concrete filled chord member. The failure modes of the four specimens under cyclic loads were observed during the tests. The hysteretic curves obtained for all the four specimens are plump and stable. Based on the hysteretic curves, the ductility ratio and the energy dissipation ratio were evaluated and compared for the four specimens. The ultimate load carrying capacities of the specimens determined from their skeleton curves are also discussed and compared.     

斜向受力十字形钢管混凝土柱抗震性能试验研究

为研究十字形钢管混凝土柱在斜向受力下的抗震性能,以加载角度(0°和45°)、混凝土强度等级(C50和C70)、轴压比(0、0.25和0.5)以及是否设置加劲肋为试验参数,进行了9根十字形钢管混凝土柱在往复荷载作用下的试验研究,获得了柱的破坏形态、水平荷载-位移滞回曲线、骨架曲线、延性、累积耗能、变形等特性,分析了不同参数对柱抗震性能的影响规律。并建立了十字形钢管混凝土柱的有限元模型,有限元分析结果与试验结果吻合良好。试验结果表明:十字形钢管混凝土柱具有较好的滞回性能,所有柱的位移延性系数均高于3.5;轴压比对十字形钢管混凝土柱的抗震性能影响较大,轴压比越大,柱承载力越低,刚度退化越快,延性和耗能能力也越差;随着混凝土强度的增加,柱承载力增加,轴压比较大时,混凝土强度越高,延性下降越明显;内部间断焊接加劲肋的柱比未设置加劲肋柱的承载力提高约8%,但延性和耗能能力提高不大;加载角度为45°柱的滞回性能稍优于0°的柱。     

装配式混凝土梁柱节点抗震性能试验研究及参数分析

为研究装配式混凝土梁柱节点的抗震性能,对1个整浇节点和2个装配式节点进行了低周往复加载试验,分析了两类节点的破坏形态、滞回性能、刚度退化、延性和耗能能力等,研究了轴压比对节点抗震性能的影响。利用ABAQUS软件建立节点的有限元模型,扩充影响参数范围,进一步分析梁纵筋配筋率、后浇区混凝土强度及连接钢板的屈服承载力对节点抗震性能的影响。结果表明：与整浇节点相比,装配式节点具有较高的承载力、刚度和耗能能力,且变形性能相当;轴压比增大时,装配式节点的承载力、刚度及耗能能力显著提高,但延性降低;提高纵筋配筋率和后浇区混凝土强度等级均可改善装配式节点的抗震性能;改变连接钢板的屈服承载力可实现梁端塑性铰向柱外侧转移,当连接钢板与梁纵筋的屈服承载力接近时,钢板可辅助节点进行耗能。     

N形方主管圆支管相贯节点受力性能试验研究

对10个N形方主管圆支管相贯节点进行了静力性能试验研究。试验节点包括6个内隐蔽部分不焊接的搭接节点、2个内隐蔽部分焊接的搭接节点和2个零间隙节点。分析了节点的受力性能、破坏模式和承载力,并对内隐蔽部分焊接情况、支管轴力性质、节点两侧主管轴压力、支管搭接情况等对节点承载力的影响进行了研究。结果表明：内隐蔽部分焊接与否对被搭接支管受拉的节点承载力影响较大,焊缝断裂是内隐蔽部分未焊接节点常见的破坏模式;在试验几何参数条件下的内隐蔽部分未焊接搭接节点在被搭接支管受压情况下的节点承载力较被搭接支管受拉时大很多;节点两侧主管均有轴压力时的搭接节点承载力较仅一侧主管有轴压力时要小;被搭接支管受拉的搭接节点承载力远远高于相应的零间隙节点。研究表明：国内外现行规范中的N形方主管圆支管搭接节点承载力计算公式对发生主管局部屈曲破坏模式的情况并不适用,而且公式也未考虑内隐蔽部分焊接与否、支管轴力性质和主管轴力等因素的影响,还有待完善。