木芯复合材料梁柱T形节点顶底角钢连接性能

针对木芯复合材料梁柱T形节点,提出设置顶底角钢的连接方式。通过6个不同构造角钢连接节点试件的单调加载试验,研究不同角钢构造对木芯复合材料梁柱节点破坏模式和承载力的影响,并简化模型,提出设置顶底角钢木芯复合材料梁柱节点的承载力计算方法。结果表明:设置顶底角钢的木芯复合材料节点构件的破坏模式可分为三种:角钢屈服破坏、梁局部压溃破坏和螺杆拉断破坏,其破坏模式受加劲肋影响;设置加劲肋顶底角钢的节点试件,其承载力分别提高30.38%,64.29%,125.62%,初始转动刚度分别提高113.75%,119.56%,227.94%。针对设置顶底角钢木芯复合材料梁柱节点,提出承载力计算公式,计算结果与试验值吻合良好。     

带加劲肋顶底角钢梁柱连接节点试验研究

为了研究带加劲肋顶底角钢梁柱连接节点受弯性能与抗震性能,分别进行了5个不同构造的角钢连接试件的单调加载试验和4种带加劲肋角钢连接试件的循环加载试验。单调加载试验结果表明:节点在负弯矩作用下,仅增设顶角钢加劲肋能够较大幅提高节点初始转动刚度与荷载,破坏模式为加劲肋处焊缝脱开;仅增设底角钢加劲肋对节点初始转动刚度影响较小,但能够增加节点的荷载。采用循环加载试验分别考察了4种不同构造的加劲肋角钢连接节点的破坏机制、滞回曲线、延性、耗能、以及刚度。结果表明:加劲肋顶底角钢连接节点是一种典型的半刚性、部分强度连接,具备良好的转动能力和耗能能力,节点破坏模式为角钢与加劲肋处呈弧状塑性铰断裂,极限弯矩对应的层间位移角均在0.04 rad以上,可满足美国规范FEMA 350不小于0.03 rad的延性设计要求。在加劲肋试件达到层间位移角0.08 rad时,节点还能够承受0.5Mmax以上的弯矩。     

角钢连接的半刚性钢框架抗震性能试验研究

在实际工程中,钢框架连接性能往往介于刚性节点和铰接节点之间,呈半刚性连接。采用拟静力试验方法进行了角钢连接的半刚性连接钢框架在低周往复荷载作用下抗震性能的试验,研究了带腹板双角钢、顶底角钢半刚性连接钢框架在周期循环荷载作用下的滞回性能、延性和破坏机理等,为钢结构抗震设计提供了一定的理论参考。试验结果表明该钢框架由于节点部位转动刚度小于刚性连接,使结构的抗侧刚度降低,侧向变形增加,但是同时也改善了梁柱的内力分布,提高了其在周期循环荷载作用下的滞回性能和耗能特性,比刚性连接钢框架具有更好的抗震性能。     

螺栓角钢钢节点的三维非线性有限元分析

对螺栓角钢钢节点半刚性连接采用非线性有限元分析方法 ,对连接中的主要构件的顶部、底部、腹板角钢、高强螺栓、梁翼缘、柱翼缘和柱翼缘加劲肋进行三维非线性有限元精细模拟 ,针对有无柱加劲肋、有无腹板角钢等几种连接的情况进行比较分析 ,探讨了螺栓角钢半刚性连接的受力性能。     

可更换加劲肋角钢自复位柱脚抗震性能试验研究

为了解决震后受损柱脚残余变形大、可恢复性能差的问题，提出了一种采用可更换加劲肋角钢的自复位柱脚，该柱脚由钢柱、钢连接件、腹板摩擦装置、可更换加劲肋角钢和无黏结钢绞线拼装而成，并由钢绞线提供复位力，通过腹板摩擦装置与加劲肋角钢塑性变形进行耗能。完成了6组共10个自复位柱脚的低周反复加载拟静力试验，对破坏形态、滞回曲线、骨架曲线、耗能、承载力与刚度退化以及残余变形与自复位能力的研究，并结合实测应变结果分析轴压比、可更换加劲肋角钢厚度、震后是否更换受损加劲肋角钢对柱脚抗震性能的影响。研究结果表明：该种柱脚的抗震性能优异，且在较大轴压比下表现出更高的承载力和耗能能力，但较大的竖向荷载会加剧残余变形与预应力的损失，导致柱脚的复位能力变差；增加可更换加劲肋角钢的厚度可增加柱脚的初期刚度和承载力；柱脚在震后不更换受损加劲肋角钢的情况下仍具有良好的承载力，可抵抗较大等级的余震作用；柱脚在震后更换受损加劲肋角钢的情况下，整体抗震性能基本可恢复至震前水平。该可更换加劲肋角钢的自复位柱脚经合理设计与控制，可以很好地实现“小震弹性，中震复位，大震更换”设计目标，为抗震设计提供参考。     

双腹板顶底角钢半刚性节点的滞回性能研究

运用非线性有限元软件ABAQUS,系统研究钢框架双腹板顶底角钢半刚性节点的滞回性能。在考虑材料非线性、几何非线性和接触非线性的基础上,对该半刚性节点进行位移控制的循环加载。并重点研究连接摩擦系数、角钢长度、角钢厚度、螺栓级别和直径、螺栓排列方式、螺栓预应力及钢材等级对节点承载力和滞回性能的影响。有限元分析结果表明:钢框架双腹板顶底角钢半刚性节点在循环荷载作用下具有良好的延性;角钢厚度、螺栓级别、直径和螺栓排列方式对节点的承载力和耗能性能影响明显,增大螺栓预应力,节点延性下降;钢材等级对节点滞回性能影响不明显。     

带加劲肋顶底角钢连接梁柱节点的有限元研究

为了研究影响钢框架带加劲肋顶底角钢连接梁柱节点的静力性能的因素,采用ABAQUS,对节点进行大量非线性有限元分析,探讨了角钢厚度、加劲肋厚度及其形状尺寸、角钢规格以及高强螺栓预紧力对节点性能的影响,得出了一些有价值的结论。     

弯剪作用下螺栓角部连接的性能分析

研究了腹板角钢尺寸对双腹板顶底角钢的弯曲-转动性能影响。研究中采用了多个三维有限元模型,以其几何和材料特性作为影响参数。在这些模型中,所有的连接组件,如梁、柱、角钢及螺栓都采用实体单元建模。构件间的相互作用效应,如螺栓滑移和摩擦,采用表面接触算法建模。为更精确地评估连接件的性能,在栓杆上施加预拉力作为第一荷载。     

L形钢管混凝土柱-H型钢梁Z字形拼接节点抗震性能研究

研究了一种L形钢管混凝土柱-H型钢梁Z字形拼接节点的抗震性能,包括翼缘和腹板均拼接的节点和设置上、下部翼缘加劲肋替代腹板处拼接板的节点.通过对节点的拟静力试验和研究,获得了节点的滞回曲线、滑移荷载、屈服荷载、极限荷载、耗能能力、延性与刚度退化规律,分析腹板处拼接板和翼缘加劲肋对节点抗震性能的影响.研究结果表明:腹板处拼接板可以提高节点的屈服荷载和极限荷载.增加翼缘高强螺栓数量可以提高节点的滑移荷载,但会降低节点的延性性能.垂直加劲肋可以提高节点的屈服荷载、极限荷载和延性.对比有无上、下翼缘加劲肋的两组节点可知,上、下翼缘加劲肋可以提高节点的承载能力,有效传递拼接区的剪力,可代替腹板连接,该节点具有良好的延性和塑性转动能力.     

钢框架梁柱角钢节点连接的抗震性能试验研究

通过对钢框架梁柱角钢连接在循环荷载作用下节点滞回性能的试验研究,分析了普通螺栓角钢连接以及高强螺栓角钢连接这两种连接类型的刚度、承载能力和延性特征,并讨论了两种连接类型的差别。从试验中还可以得出,腹板角钢对连接的承载力有明显改善,在计算连接抗弯承载力时应考虑腹板连接的影响。     

剪力对带腹板双角钢顶底角钢初始刚度的作用分析

主要分析了带腹板双角钢顶底角钢的弯矩-转角关系,尤其是在剪力和弯矩共同作用下的初始刚度。采用数个三维有限元模型进行分析,将连接件的几何和力学性能作为参数。模型中,所有的连接构件如梁、柱、焊接角和螺栓的建模都采用八节点单元。所有构件的相互作用,如螺栓滑移、摩擦力等,采用表面接触计算法则进行模拟,为更准确地评估连接性能,在螺栓杆处采取预拉伸模拟其初受力状态。通过将数值模拟的结果与试验结果进行对比发现,它们具有良好的一致性。为评估剪力在这种连接中的作用,通过数个不同量级剪力的模型分析发现,剪力对角钢连接初始刚度的影响呈减弱趋势。因此提出一个公式,根据在无剪力情况下连接件的初始刚度和屈服弯矩,计算在任何可能产生剪力的条件下连接件初始刚度的换算系数。     

Refined 3D finite element modeling of partially-restrained connections including slip

This study presents an approach for refined parametric three-dimensional (3D) analysis of partially-restrained (PR) bolted steel beam-column connections. The models include the effects of slip by utilizing a general contact scheme. Non-linear 3D continuum elements are used for all parts of the connection and the contact conditions between all the components are explicitly recognized. A method for applying pretension in the bolts is introduced and verified. The effect of several geometrical and material parameters on the overall moment–rotation response of two connection configurations subject to static loading is studied. Models with parameters drawn from a previous experimental study of top and bottom seat angle connections are generated in order to compare the analyses with test results, with good prediction shown by the 3D refined models. The proposed 3D modeling approach is general and can be applied for accurate modeling of a wide range of other types of PR connections. A pronounced effect of slip and friction, between the connection components is shown with connections having thicker (stiffer) seat angles. This study demonstrates the effects of clamping through the bolts and contact between the components on the overall non-linear moment–rotation response. Equivalent moment–rotation responses of pull-test simulations are compared to FE model responses of full connections without web angles. The moment–rotation from the pull test is shown to be equivalent to that of the full FE model for small rotations. As the rotation increases a softer response is shown by the pull tests.     

既有简支薄壁C形钢檩条连续化加固研究

为提高既有简支薄壁C形钢檩条的承载能力,对相邻简支C形钢檩条在支座附近采用内嵌薄壁L形钢连接成为连续檩条。对仅腹板有螺钉连接和腹板及上、下翼缘均有螺钉连接的2组加固C形钢檩条进行静力加载试验,分析了加固后檩条的破坏模态、刚度、延性、承载能力及应变发展,并与简支C形钢檩条的受力性能进行了对比。试验结果表明：加固试件的两跨檩条以整体弯曲变形为主,C形钢檩条跨中和加载处上翼缘与受压区腹板发生局部屈曲而破坏,薄壁L形钢翼缘达到屈服。简支檩条连续化加固后的承载能力、刚度均有显著提高,延性提高较小。腹板及上下翼缘均有螺钉连接加固檩条的刚度和屈服荷载提高幅度明显高于仅腹板螺钉连接加固,但两者极限荷载和延性差别较小。采用三线性钢材本构模型和壳单元,建立了同时考虑几何非线性和材料非线性的三维有限元模型进行数值模拟,计算结果与试验结果的对比验证了有限元模型的准确性。分析了不同薄壁L形钢长度对加固檩条受力性能的影响,结果表明,薄壁L形钢长度的增加对承载能力、刚度的提高幅度由大变小,刚度的提高幅度大于承载能力的提高幅度,薄壁L形钢长度宜取檩条单跨跨度的10%~15%。     

Behavior of bolted angle connections subjected to combined shear force and moment

In this paper, the effect of web angle dimensions on moment-rotation behavior of bolted top and seat angle connections, with double web angles is studied. Several 3D parametric finite element (FE) models are presented in this study whose geometrical and mechanical properties are used as parameters. In these models, all of the connection components, such as beam, column, angles and bolts are modeled using solid elements. The effect of interactions between components, such as slippage of bolts and frictional forces, are modeled using a surface contact algorithm. To evaluate the behavior of connection more precisely, bolt pretensioning force is applied on bolt shanks as the first load case. The results of this numerical modeling are compared with the results of experimental works done by other researchers and good agreement was observed. To study the influence of shear force on behavior of these connections, several models were analyzed using different values of shear force. The effect of important parameters, especially the effect of web angle dimension, is studied then. An equation is proposed to determine the reduction factor for initial rotational stiffness of connection using connection initial rotational stiffness, yield moment, the expected shear force and web angle dimension. The proposed equation is compared with other existing formulations and it was observed that the proposed model is a better estimator of connection behavior.     

自复位钢框架节点有限元模拟及参数分析

研究了一种具有自复位能力的钢框架节点的力学性能.该节点在梁柱间通过角钢栓接,并沿梁长布置高强预应力钢绞线.通过对钢绞线施加预应力将梁柱压紧,使节点具备足够的抗弯刚度以满足正常使用情况下的功能性要求,钢绞线同时提供回复力,使节点在地震后具有自复位能力.采用通用有限元分析软件Abaqus 6.9建立节点模型,对9个足尺钢框...     

The behavior of top and seat bolted angle connections under blast loading

Abnormal loading generated by blast or impact may cause local damage in a building that may evolve to affect the whole structural system. Therefore, structures have to be designed to prevent such disproportional consequences. Connection is an important contributor to ductility and robustness of the structural steel systems in mitigating such consequences. Considering this importance, finite element analysis is used in this paper to study the behavior of top and seat bolted angle connections under blast loading. The two frequent angle connections including top and seat angle bolted connections with and without web angles are studied using the ANSYS finite element software. The finite element models are verified by comparing the predicted results obtained from the models and the values measured in the experimental tests. Simplified blast loading is then applied to the verified connection models and the behavior of these connections under blast loads is evaluated with the connection critical areas being determined. The connection failure modes as well as the applicability of the connection under blast loading are briefly discussed.     

双腹板、顶底角钢半刚性节点试验与应力应变分析

研究连接的受力性能并确定计算模型是研究半刚性节点的基础。为此对双腹板、顶底角钢半刚性节点的试验数据进行分析 ,绘出试件各组合件关键点的荷载 -应变关系曲线。荷载 -应变关系曲线是分析各细部的受力变形特征和试件在加载过程中受力缺陷 (如扭转 )的有效手段。通过数据分析 ,阐述了试件各组合件在静力荷载作用下的受力机理 ,验证了节点的计算模型 ,为进一步研究半刚性节点提供依据。     

Performance of bolted angle connections in progressive collapse of steel frames

This paper is mainly focused on the behaviour of bolted top‐seat angle connections with double web angles, categorized as partially restrained connections, in progressive collapse of semi‐rigid steel frames due to sudden column loss. The main characteristics of this type of loading are declared and the effect of the imposed boundary conditions on the motivated elements is depicted. To study the performance of frame connections under these conditions, refined nonlinear finite element modelling technique is used. The models are created based on the previous experimental studies and their accuracy is examined through a comparison to the results of these tests. New models are created under conditions of the progressive collapse and the behaviour of the connections is studied. The study showed that due to the applied boundary conditions, the connections behave stiffer and show a higher moment capacity. Based on the results of the numerical models, equations are presented to estimate the moment‐rotation response of the studied connections under progressive collapse conditions based on the beam and connection mechanical and geometrical properties and the connection rotation. Copyright © 2009 John Wiley & Sons, Ltd.