全装配式外套筒-加强式外伸端板组件梁柱连接节点抗弯承载力研究

提出全装配式外套筒-加强式外伸端板组件梁柱新型连接节点,通过理论分析、试验研究和有限元分析,确定了节点受力计算模型,推导出节点抗弯承载力理论计算式,并与有限元模拟值和试验结果进行比较,三者吻合较好,证明其具有合理性和良好的适用性。所提出的节点抗弯承载力计算方法可为该类节点的设计和计算提供理论工具。试验研究与有限元分析还表明,装配式外套筒-加强式外伸端板组件梁柱连接节点的屈服机制为:外套筒和柱壁内凹受压屈曲、外伸端板压屈、节点屈服;梁柱连接节点具有良好的耗能能力,增大外套筒厚度,节点屈服荷载增加,耗能能力提高。     

方钢管柱-H字钢梁套管加强式端板连接节点抗震性能分析

为了研究方钢管柱-工字钢梁套管加强式端板连接的抗震性能,利用大型有限元软件AN-SYS,考虑几何非线性、材料非线性和状态非线性对方钢管柱-工字钢梁套管加强式端板连接节点进行了循环荷载作用下的有限元分析,分析了端板厚度对梁柱节点滞回性能的影响及节点承载力、初始转动刚度,耗能能力和延性的影响。计算结果表明:方钢管柱-工字钢梁套管加强式端板连接具有良好的延性和耗能能力。     

外伸端板SMA螺栓连接自复位钢框架去柱抗倒塌性能分析

为明晰外伸端板形状记忆金属(Shape memory alloy,简称SMA)螺栓梁柱连接自复位钢框架去柱后结构的抗倒塌性能,采用ANSYS软件建立了梁、实体混合单元模型。在验证有限元模型合理的基础上,进行外伸端板SMA螺栓、高强度螺栓柱连接去柱子结构竖向加载分析,并对比两类试件的受力性能及复位效果。研究表明:两类试件应力(应变)分布相似,且应力集中在外伸端板上侧及梁翼缘与端板连接处;中柱竖向力-位移曲线呈三段式分布,SMA螺栓连接试件加载后期悬链作用显著,且竖向承载力高于高强度螺栓连接试件; SMA螺栓连接可有效减小结构残余变形,降低结构的修复难度,提高修复的经济性。     

门式刚架轻型房屋钢结构端板连接的有限元与试验分析

结合门式刚架轻型房屋钢结构中普遍应用的端板连接方式 ,本文对梁柱节点和梁拼接节点进行了试验和有限元分析 ,对外伸式端板连接的承载力和转动刚度特性进行了研究 ,讨论了我国现行规范关于外伸式端板连接的设计方法中存在的问题 ,同时给出了改进建议 ,特别是提出了在建立钢结构节点刚度分类标准方面应该注意的问题。根据比较分析的结果 ,本文还提出了一种新的外伸式端板连接螺栓拉力分布模型及相应的设计方法 ,试验证明 ,该方法在保证安全可靠的前提下 ,能够更好地符合螺栓端板连接的实际受力状态 ,发挥螺栓和端板的承载能力     

高强螺栓外伸端板撬力作用的有限元分析与设计方法

针对外伸端板与T型连接设计中考虑撬力影响的问题,利用ANSYS进行了三维非线性有限元分析,考虑了材料非线性、几何非线性、高强螺栓的预拉力、端板间接触压力的影响。证明了撬力的存在以及螺栓拉力的分布是以受压翼缘位置为转动中心的梯形分布,提出了外伸端板连接中螺栓拉力的计算模型。研究了高强螺栓受拉连接采用外伸端板或T型接头的破坏机理以及撬力作用计算理论。介绍了国内外关于外伸端板与T型连接设计中考虑撬力作用的端板厚度设计方法,为工程设计提供了参考依据。     

外伸端板高强螺栓连接三维非线性有限元分析

对外伸端板高强螺栓连接采用三维非线性有限元分析方法,对连接中的主要构件端板、高强螺栓、梁翼缘、柱翼缘和柱翼缘加劲肋进行精细模拟,针对有无柱加劲肋、端板厚度变化等连接的情况进行比较分析,研究了外伸端板高强螺栓半刚性连接的受力性能以及其初始刚度的影响因素。     

门式刚架轻钢结构端板连接节点承载性能的有限元分析

采用ANSYS有限元软件建立了考虑接触和螺栓预拉力的三维有限元模型,对带加劲肋的外伸式端板连接节点进行了非线性分析,讨论了端板厚度、连接形式对端板连接节点的承载力和节点刚度特性的影响,同时对现行规范的相关设计原则进行了分析和验证,并提出了一些设计建议。     

外伸式端板螺栓连接节点的有限元分析

利用有限元ANSYS对外伸式端板螺栓连接节点受力性能进行了分析,从改变端板厚度和螺栓直径方面进行了节点受力性能研究,提出了钢框架结构设计节点时可按构造形式划分螺栓受力模型。     

外伸端板连接节点抗连续倒塌性能研究

基于ANSYS有限元分析软件,建立了外伸端板连接节点模型,分析了半刚性节点在连续倒塌中的力学性能,基于该模型进行了外伸端板连接节点抗连续倒塌能力影响因素的参数分析,为相关设计提供参考。     

波纹腹板H型钢梁柱半刚性外伸端板连接性能研究

为研究波纹腹板H型钢梁柱半刚性外伸端板连接的性能,采用有限元软件ANSYS,对外伸端板连接进行单向静力加载模拟,得到弯矩-转角曲线和端板应力云图,分析连接受力特性;分别调整端板厚度和梁腹板高厚比,分析其对弯矩-转角曲线的影响。结果表明:随着弯矩的增加,弯矩-转角曲线由线性特征转变为非线性特征,连接刚度逐渐降低;端板厚度和梁腹板高厚比对连接的初始刚度及抗弯承载力均有显著的影响。     

Numerical modelling of restrained structural subassemblies of steel beam and CFT columns connected using reverse channels in fire

This paper employs the general finite element software ABAQUS to numerically model the behaviour of restrained structural subassemblies of steel beam to concrete filled tubular (CFT) columns and their joints in fire. The simulations were conducted using 3-D brick elements to enable detailed structural behaviour to be obtained. For validation, this paper compares the simulation and test results for the three fire tests using reverse channel connection recently conducted at the University of Manchester. This comparison demonstrates that the 3-D finite element model is able to successfully simulate the fire tests. Afterwards, the validated finite element model was used to conduct a preliminary numerical study to investigate the feasibility of changing some of the connection details to enhance survivability of the structure in fire. Specifically, this investigation concentrated on developing connection methods to enable catenary action in the connected beam to be more fully developed. An example is to develop a hybrid flush/extended endplate and flexible endplate connection in which the tension part of the connection uses a flush/extended endplate for increased tensile resistance but the compression part of the connection uses a flexible endplate for improved ductility. It has been found that, without additional cost, using a hybrid extended/flexible endplate connection to replace a flush endplate connection has the potential to enable the connected beam to survive significantly increased temperature.     

Resistance of flush endplate connections under tension and shear in fire

This paper presents an experimental and numerical study to the resistance of flush endplate connections in fire. Six transient fire tests were performed on two types of connections with flexible and stiff endplate. For each connection, three load combinations were tested and the test results were reported. The test shows that most connections failed within the range of 500 °C to 650 °C. Extreme bending deformation of the endplate and flexural deformation of the bolt were observed when the plate thickness was 8 mm. When the endplate thickness became 16 mm, deformations occurred to the column flange and the bolts as the endplate became thicker than the column flange. Connection fire resistances were found to decrease with increase of either tension or shear, but the connection deformations were similar regardless of the load combination within the range tested. The three-dimensional finite element simulations of the tests with flush endplate connections were conducted with general-purpose finite element program ABAQUS. The results obtained from analysis showed a good agreement with the experimental responses. Parametric study was performed to the connection failure mechanisms under an extensive range of load combinations of tension and shear in fire using the finite element model. Conclusions were drawn regarding the tension and shear interactive relationships for the two typical connections at different temperatures.     

火灾下梁柱端板式节点研究进展

回顾总结了近年来高温下梁柱端板式连接节点力学性能相关的研究成果。针对三类常用的端板连接形式:外伸式端板、齐平式端板以及内缩式端板连接进行了细致讨论。同时,从试验研究、有限元分析以及组件法的高温运用等方面着手归纳了相应研究成果。首先,对近年来为数不多的端板式节点高温试验进行了回顾,包括针对孤立节点的高温试验以及针对子结构的高温试验。随后,对有限元方法和推广应用的组件法这两种理论研究方法进行了详细的归纳总结,细致讨论了各组件模型实际运用中的优势以及存在的不足。最后,根据已有的研究成果,指出了梁柱端板式连接节点性能分析时还存在的诸多问题,并在此基础上提出了一些研究建议。     

改善钢梁/柱连接节点耐火性能的方法

在有限元分析软件中使用详细的有限元模型,对提升钢梁/柱端板连接部件的耐火性能进行一系列的数值参数研究。对实际使用节点构造的梁柱组件进行研究,重点在于调查如何改进连接件设计,从而使整个结构能在高温下安全。高温下,结构中的梁要经历悬链作用,此作用会造成连接件的破裂并在柱施加附加力。研究了不同的节点构造(螺栓直径、螺栓强度级别、端板厚度、使用防火螺栓和端板使用耐火钢)对其结构性能及高温下耐火性能的影响。结果表明,可通过提高连接件的变形能力特别是使用防火螺栓来改善在高温下的耐火性能。     

Methods of improving survivability of steel beam/column connections in fire

This paper reports the results of a series of numerical parametric studies on methods of improving survivability of steel beam/column endplate connections in fire using a detailed finite element model in ABAQUS. The parametric studies were performed on beam-column assemblies with realistic connection details and the main focus of this research is to investigate methods of improving connection design to enable the structure to survive very high temperatures. At very high temperatures, the beam of the structure experiences catenary action which may fracture the connections and exert additional forces on the columns. This paper investigates how different connection details (bolt diameter, bolt grade, endplate thickness, the use of fire resistance bolt and fire resistant steel for endplate) affect structural behavior and survivability at high temperatures. It is found that improving connection deformation capacity, in particular, using fire resistant bolts, will enable very high temperatures to be resisted.     

Modelling of I-shaped beam-to-tubular column connection subjected to post-fire conditions

This paper presents numerical results of structural post- fire bahaviour of I-shaped beam-to-chord joints in offshore platforms topside. Considering the high risk of fire events in offshore oil/gas platforms, this study focuses on the structural behaviour of these connections at post- fire condition. A highly detailed three-dimensional (3-D) finite element (FE) model of this connection has been created using the ABAQUS software. Steel members and connection components are considered to behave nonlinearly. The results of finite element and experimental tests conducted on I shape beam-to-tubular column connections in furnace fire conditions are compared, and the obtained failure modes and moment-rotation-temperature characteristics are in good agreement with those associated with experimental tests. The validated model has been used to conduct numerical parametric studies to generate theoretical data to help develop detailed understanding of the joint behaviour in post-fire condition.     

Finite element analysis of flush end-plate connections connected to column web

Eurocode 3: Part 1.8 (2005b) does not cover the empirical design for flush end-plate connections connected to column web. Thus, experimental works need to be performed to investigate the behaviour of the minor axis end-plate bolted connection. However, the experimental tests are expensive, tedious and time consuming to be conducted. Alternatively, finite element modelling and analysis can be adopted to predict the behaviour of the connection accurately. Five specimens of flush end-plate connections connected to column web with variable parameters have been tested and the results are compared with finite element analysis. Finite element models with enhanced strain solid and contact joint elements are used to stimulate the connection behaviour. The objective of this paper is to compare and validate the accuracy and reliability of the finite element model by correlating moment rotation (M-Φ) curves between the finite element model and experimental tests. The comparison shows a reasonable agreement between the predicted results from FEA and the experimental tests.     

Finite element modelling of steel fin plate connections in fire

Recent structural collapses caused by fire have focused attention on research concerning fire safety in building design. Steel connections are an important component of any structural steel building, as they provide links between the principal structural members. The evaluation of the performance of steel connections at elevated temperatures has been a topic of several research programmes in the last few years. Determining the behaviour, available strength and stiffness of moment connections in fire conditions has been a dominant theme in these research works; however very little information on the behaviour of simple shear connections in fire conditions has been disseminated. Fin plate shear connections are easy to fabricate and install; as a result, they have gained popularity with fabricators because of their economy. In this research, the robustness of simple fin plate beam-to-column connections is being investigated under catenary tension from highly deflected beams in fire. A highly detailed three-dimensional (3-D) finite element (FE) model has been created using the ABAQUS software. This is a complex model accounting for material and geometric non-linearity, large deformation and contact behaviour. Contact is critical to model the shear behaviour of the joint, and contact elements have been used both at the bolt–hole interface and also at the surface between the web of the beam and the fin plate, taking into consideration friction between the surfaces. The connection model has been analysed through the elastic and plastic ranges up to failure. Bolt shear and bending, and plate and web bearing have been observed as failure modes. A comparison between available experimental data at ambient and elevated temperatures and other analytical results shows that the model has a high level of accuracy. When the connection model was extended to include an attached beam, it was found that it eventually experiences large tensile force when exposed to fire.     

Nonlinear behaviour of unprotected composite slim floor steel beams exposed to different fire conditions

An efficient nonlinear 3D finite element model has been developed to investigate the structural performance of composite slim floor steel beams with deep profiled steel decking under fire conditions. The composite steel beams were unprotected simply supported with different cross-sectional dimensions, structural steel sections, load ratios during fire and were subjected to different fire scenarios. The nonlinear material properties of steel, composite slim concrete floor and reinforcement bars were incorporated in the model at ambient and elevated temperatures. The interface between the structural steel section and composite slim concrete floor was also considered, allowing the bond behaviour to be modelled and the different components to retain its profile during the deformation of the composite beam. Furthermore the thermal properties of the interface were included in the finite element analysis. The finite element model has been validated against published fire tests on unprotected composite slim floor steel beams. The time–temperature relationships, deformed shapes at failure, time–vertical displacement relationships, failure modes and fire resistances of the composite steel beams were evaluated by the finite element model. Comparisons between predicted behaviour and that recorded in fire tests have shown that the finite element model can accurately predict the behaviour of the composite steel beams under fire conditions. Furthermore, the variables that influence the fire resistance and behaviour of the unprotected composite slim floor steel beams, comprising different load ratios during fire, cross-section geometries, beam length and fire scenarios, were investigated in parametric studies. It is shown that the failure of the composite beams under fire conditions occurred for the standard fire curve, but did not occur for the natural fires. The use of high strength structural steel considerably limited the vertical displacements after fire exposure. It is also shown that presence of additional top reinforcement mesh is necessary for composite beams exposed to short hot natural fires. The fire resistances of the composite beams obtained from the finite element analyses were compared with the design values obtained from the Eurocode 4 for composite beams at elevated temperatures. It is shown that the EC4 predictions are generally conservative for the design of composite slim floor steel beams heated using different fire scenarios.