空间外伸端板连接节点初始转动刚度研究

基于平面节点初始转动刚度计算的组件法,对空间外伸端板连接节点的初始转动刚度进行理论和有限元分析。确定了对空间外伸端板连接节点初始转动刚度有贡献的各组件,结合已有的研究和空间节点受力性能特点,给出了各组件的刚度计算式;根据弹性阶段各组件的变形对空间外伸端板节点整体变形的贡献,提出了在对称荷载作用下空间端板连接节点初始转动刚度计算模型,并以此得到了空间端板连接节点初始转动刚度理论计算式。同时,建立了空间端板连接节点有限元模型进行参数化有限元分析,并与理论分析结果进行比较,有限元分析与理论计算结果吻合较好,验证了文中理论计算式的有效性。     

钢框架梁柱连接节点转动刚度试验研究

为了探讨钢框架梁柱连接节点的转动刚度和破坏模式,针对常见梁柱节点类型,包括全焊接连接、外伸式端板螺栓连接、T型钢螺栓连接、上下翼缘及腹板角钢螺栓连接等,进行了单向加载试验研究。试验结果表明,各类节点的总转角均超过了0.05 rad,塑性转角均超过了0.04 rad;节点域剪切变形较大,特别是全焊接节点,使节点转动刚度显著降低;当连接较强时,框架梁可以在连接破坏之前形成塑性铰;当连接较弱时,连接件容易因过度变形而破坏。通过对试验数据的分类整理分析,梁柱节点总转角可以分成节点域转角和连接转角两大部分,给出了常见节点类型在弹性阶段的转角及转动刚度简化计算方法,并与试验结果进行了对比,计算结果与试验结果吻合较好。     

竖向荷载下半刚性连接组合框架梁的承载能力极限状态设计

论述了半连续框架设计原理,提出用塑性分析方法计算竖向荷载下半刚性连接组合框架梁在承载能力极限状态的内力,并给出了具体的设计步骤,最后用两榀足尺的两层两跨的半刚性连接组合框架试验验证了塑性分析方法。研究表明,半连续框架设计可用塑性分析方法获得弯矩图,不同于连续框架设计用弹性分析方法获得弯矩图;塑性分析方法考虑了组合梁的跨中弯矩承载力、节点弯矩承载力、节点转动能力和设计需要的节点转动能力,适用于竖向荷载下半刚性连接组合框架梁的承载能力极限状态设计。该方法简单实用且比较准确,可供工程设计参考。     

特高压输电塔半刚性连接K形节点受力性能研究

基于螺栓受剪半刚性K形节点理论分析及有限元模型提出一种适用于此类节点的计算模型和计算方法。该方法能够较好地分析半刚性连接K形节点转动变形的组成,包括主角钢剪切变形、螺栓剪切变形、螺栓孔的变形。考虑主角钢受剪、螺栓受剪、孔壁变形对节点转动刚度的影响,从而得到节点弯矩-剪切转角(M-s)和弯矩-转角(M-)曲线。通过试验验证了该计算方法的适用性。提出的半刚性连接K形节点弯矩-转角建议计算方法量化了主角钢肢宽、肢厚、螺栓直径、节点板厚度对转动刚度的影响,但未考虑主角钢两肢边相互影响。建议计算方法也可为我国输电塔结构设计规范关于节点转动变形的具体设计提供参考。Kishi-Chen的三参数幂函数模型适用于对此类节点弯矩-转角计算,输电塔结构中此类节点的形状系数取值大致在1.5~2.2之间。     

梁柱端板连接节点的初始转动刚度计算模型

首先利用分解法建立了梁柱螺栓端板连接节点的力学模型 ,然后基于梁板理论给出了节点初始转动刚度的解析公式。公式综合考虑了端板变形、柱翼缘以及螺栓对初始转动刚度的贡献 ,可方便地推广于平端板和外伸加劲端板连接初始转动刚度的计算。公式计算结果和试验结果以及有限元分析结果作了对比 ,吻合较好。同时给出了便于工程设计的简化公式。     

基于子结构的薄钢板PEC柱-钢梁组合框架层间倒塌机理分析

为揭示薄钢板组合截面部分外包混凝土组合PEC柱-钢梁组合框架中间层倒塌机理,本文利用商业有限元软件ABAQUS,对采用预拉对穿螺栓端板狗骨式连接的薄钢板组合截面PEC柱-钢梁组合框架中间层子结构试验试件建模,并进行水平低周往复荷载下抗震性能的有限元分析。基于计算结果,分析试件结构的承载力与抗侧刚度、节点连接转动性能、耗能能力、剪力分配、变形模式、节点区传力机理和破坏模式等抗震性能。研究结果表明:试件具有较高的承载力和较大的初始抗侧刚度;PEC柱平均分担试件层间水平剪力;预拉对穿螺栓表现出部分自复位功效;梁端截面削弱实现了塑性铰位置远离节点区,且保证了连接具有良好的转动能力和结构耗散地震能能力;试件最终破坏模式为所有梁端削弱截面形成塑性铰的塑性倒塌机构,对应节点连接转角和层间剪切角均满足中震层间侧移限值1/50要求,表明该结构体系具有良好的耗能能力和抗倒塌性能。     

梁柱连接组合节点弯矩-转角关系研究

梁柱连接组合节点传递着梁柱之间的弯矩和剪力,是钢框架中的重要组成部分,也是钢框架设计中的关键部位之一。弯矩-转角关系是梁柱连接组合节点的主要力学性能,它反映着节点的初始刚度、抗弯承载力和转动能力,直接影响着钢框架体系的变形、极限承载力与整体性能。梁柱连接组合节点连接方式多样、构造形式种类繁多、几何参数多变、各组件受力状态与性能复杂等特性决定了弯矩-转角曲线是非线性的。而弯矩-转角曲线的非线性造成其难以拟合和预测。目前,半刚性连接组合节点的试验与理论研究有了较大的进展。本文归纳和总结了国内外梁柱半刚性连接组合节点弯矩-转角关系研究,包括试验研究和理论模型,并指出了今后需要进一步研究的重点与方向。     

钢-混凝土组合节点平齐式端板连接抗震性能试验研究

为研究混凝土板内纵向钢筋配筋率和柱翼缘填充混凝土对平齐式端板连接钢-混凝土组合节点抗震性能的影响,对1个平齐式端板连接钢-混凝土组合梁与组合柱节点和3个平齐式端板连接钢-混凝土组合梁与钢柱节点进行了低周反复加载试验,研究了节点试件变形特征与破坏模式、弯矩-转角滞回曲线及骨架曲线等,探讨了试件承载力、承载力退化、延性及耗能能力等的影响,利用组件法对负弯矩作用下的梁端初始转动刚度进行了分析计算,并建立了考虑刚度退化的恢复力模型。研究结果表明:提高混凝土板纵向配筋率可有效提高在负弯矩作用下的梁端极限弯矩和初始转动刚度,但对正弯矩作用下的梁端极限弯矩与开裂弯矩影响不大;采用柱翼缘填充混凝土可有效提高梁端初始转动刚度和延性;提出了梁端初始转动刚度计算式,其计算结果与试验结果吻合较好。     

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。     

梁柱节点剪切变形计算模型基本假定的校核

现有钢筋混凝土梁柱节点的剪切变形计算模型包含两个基本假定,即矩形的节点核心区发生剪切变形后变为平行四边形,以及4个角点沿矩形原对角线伸长或缩短,且对角线不转动。基于ABAQUS有限元软件,以多组钢筋混凝土梁柱组合体试验结果为依据,对有限元模型的合理性进行了校核,并在此基础上对单调加载和反复加载下钢筋混凝土中间层中节点的受力性能进行了模拟。提取了变形后节点核心区4个角点的坐标数列,根据几何关系直接计算了节点剪切变形,并将其与试验实测结果进行了对比,验证了节点剪切变形计算模型基本假定的合理性。分析结果表明,计算模型采用的平行四边形假定是合理的,但对角线不转动假定存在一定误差。节点对角线转动角度将影响梁端、柱端方向的节点剪切角的计算精度,建议对现有节点剪切变形计算公式进行修正。     

节点刚度对轻型门式刚架结构设计的影响

介绍了工程上通常采用的端板连接形式 ,并采用有限元模型对连接节点的变形特征进行了分析 ,研究了节点刚度变化对刚架设计的影响 ,并结合工程实际提出了设计建议。     

Experimental and analytical behavior of bolted end-plate connections with or without stiffeners

This paper presents the experimental results of eight specimens of steel bolted connections beam-to-column and beam-to-beam with flush or extended endplate. Four of the connections have the end-plates reinforced with stiffeners in the extended parts. The column used is with low resistance to observe the competition between the failure modes in the tension and compression zones. The results are analyzed on the basis of the global moment–rotation curves and the evolution of the tension forces in the bolts. The main parameters observed are the failure modes, the evolution of the resistance, the stiffness and the rotation capacity. The experimental results are used as a basis of comparison with the analytical results given by the component method of Eurocode 3. The main goal of this comparison is to evaluate the accuracy of the analytical method including the connections with stiffeners in the extended part of the end-plates.     

Compound-element modeling accounting for semi-rigid connections and member plasticity

A general model of a compound element is proposed in this article to consider the combined influence of semi-rigid connections and plasticity on the non-linear responses of steel frameworks. The stiffness degradation of semi-rigid connections is modeled by a moment–rotation relationship with four parameters, while the plasticity formation of a member end from initial yield to full yield is modeled by an elliptic moment–rotation relationship. The compound element resulting from the combined influence of member plasticity and semi-rigid connection behaviour is used to facilitate the derivation of member stiffness coefficients where the effects of geometrical non-linearity and member shear deformation are also included for the progressive-failure analysis. On the basis of member plasticity behaviour, the categories of semi-rigid connections are investigated. Three semi-rigid steel frameworks are analysed to illustrate the proposed analysis method, and the results are compared with those obtained from experiments and the application of other methods.     

多层钢框架中梁柱端板连接的强度和刚度

端板连接的构造特点决定了其在具有较强承载能力的同时还具有一定的柔性,有别于传统的刚接和铰接。针对这一现象,本文论述了多层钢框架结构中梁柱端板连接的强度和刚度问题,包括连接的构造形式、端板和螺栓的计算方法、节点域柱腹板的受力状态以及加劲肋的作用,根据端板连接的简化力学模型提出了确定连接极限承载力和转动刚度的方法,其中转动刚度主要与节点域剪切刚度和端板抗弯刚度有关。最后,结合连接的荷载.位移曲线特点推导出单向加载和循环加载下连接的简化弯矩转角关系,并与相关数据结果作了对比验证,该方法简单实用且比较准确,可供结构计算和节点设计参考。     

Moment resistance and rotation capacity of semi-rigid composite connections with precast hollowcore slabs

Semi-rigid composite connections with precast hollowcore slabs are a newly developed technique with few applications in current construction practice. The research on the structural behaviour of this new type of connection is limited, with no existing method available to predict its important characteristics such as moment and rotation capacities. In this paper, based on the parametric studies of the three-dimensional finite element model and full-scale tests, analytical methods to calculate the moment and rotation capacity of this type of composite joint are proposed. A comparison between the proposed calculation method and the full-scale test results was made, and good agreement was obtained.     

Requirements for moment connections in statically indeterminate timber structures

In statically indeterminate structures, connections play a vital role in the moment distribution. Demonstrated here is a method to evaluate the conditions, taking full advantage of the benefits offered by the indeterminate nature of the structures, and using the well-established, graphical beam-line method. This method shows how important the immediate load take-up is, the stiffness, the moment capacity of the connection and how it all affects the structural behaviour. The examples considered here use both the traditional non-reinforced dowel-type fastener connections and also timber connections reinforced with steel plates. They show that the minimum rotation requirements to achieve an effective structure are satisfied easily in contrast to requirements on stiffness. In this respect, timber connections with local reinforcement glued at the interface of the connection area offer more prospects.     

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.     

Behavior of Khorjini connections in fire

Beam-to-column connections have been shown to have great influence on structural behavior at ambient and elevated temperatures. When steel-framed structures are subjected to fire, the load-bearing capacity is decreased and the behavior of the joints is of particular concern. In this paper, the behavior of a semi-rigid Khorjini connection is studied at elevated temperatures. Four experimental tests are carried out on this kind of connection at elevated temperatures, and the results are presented as temperature–rotation and moment–rotation curves. Then, finite-element models are developed and compared with the experimental tests. Good agreement was achieved between the model and experiment, confirming that the finite-element method is capable of predicting the behavior of these connections at elevated temperatures.     

宽肢组合异形柱-钢梁节点抗震性能试验研究

为研究适用于高层钢结构住宅体系的组合异形柱框架结构的翼缘加强型节点的抗震性能,设计了两种不同构造形式的足尺节点试件,即格构式宽肢组合异形柱节点和实腹式宽肢组合异形柱节点,并进行拟静力试验,研究了该类节点的破坏形态、滞回性能、承载能力、梁端转角、延性及耗能能力。试验结果表明：2个节点最终均在加强件端部发生了翼缘开裂而破坏;节点的受弯承载力是梁端全截面塑性承载力的1.10~1.13倍;钢梁转角是梁端总转角的主要组成部分,节点区转角只占梁端总转角的1.0%~1.8%,柱变形转角占9.2%~13.0%;节点的位移延性系数约为2.33~2.38,黏滞阻尼系数约为0.264~0.267。此外,2个节点的承载能力基本相当,格构式宽肢组合异形柱节点的抗震性能指标相对实腹式宽肢组合异形柱节点较好;但与传统翼缘加强型节点相比,其延性和耗能能力略有降低。     

带或不带加劲肋螺栓连接端板性能试验及分析

给出了8个梁-柱、梁-梁外伸端板螺栓连接试样的试验结果,其中4个连接件在外伸端板处使用了加劲肋。将低阻力螺栓受拉区和受压区的失效模式进行对比,基于整体弯矩-转角曲线和螺栓拉应力的发展对试验结果进行分析。试验主要关注失效模式、阻力发展、刚度及扭转能力。将试验结果与按照EC3提供的方法得到的分析结果进行对比,评估该分析方法(包括分析外伸端板处使用了加劲肋的连接件)的准确性。