木构件钢填板预应力套管螺栓连接的性能参数分析

本文采用ABAQUS建立了木构件钢填板预应力套管螺栓连接节点在顺纹和横纹受力下的有限元分析模型。通过将有限元分析得到的节点极限承载力、极限变形和初始刚度与试验结果进行对比,发现有限元值和试验值相差均在10%以内,从而验证了有限元模型的合理性。基于有限元模型,本文分析了连接中管板摩擦系数、螺杆预应力值以及钢管壁厚对节点荷载变形曲线的影响,具体讨论了上述参数对节点极限承载力、极限变形、极限抗滑移承载力的影响,还对达到极限承载力时节点内部的力分配进行了参数分析。通过参数分析,对节点的合理设计提出了建议。     

新型带悬臂梁段栓-焊拼接节点力学性能研究

以提出的新型带悬臂梁段栓-焊拼接节点的试验数据为基础,从节点极限承载力、破坏模式、各部件应力分布及塑性区扩展等方面进行非线性有限元模型校验,基于校验后的模型研究了几何、材料及荷载等参数对节点初始刚度及极限弯矩的影响,并提出了节点设计方法。有限元分析结果表明,单向荷载作用下,法兰板的厚度对节点初始刚度的影响较大,当板厚大于20mm时,节点初始刚度和极限承载力显著增加;往复荷载作用下,连接法兰板的螺栓孔周围出现了明显的应力集中现象,随着荷载的增大,高强度螺栓由摩擦型转为承压型;该类型节点力学性能良好,符合工业化装配式钢结构体系设计要求。     

柔性连接下全轻骨料混凝土预制墙板的受弯性能试验研究

设计了一种内嵌式墙板柔性连接方式,对在这种柔性连接下的6块全轻页岩陶粒预制墙板进行了抗弯承载力试验研究,主要研究参数为框架梁与预制墙板连接节点的位置、个数和墙板开窗洞情况。对墙板的荷载-挠度曲线、荷载-应变曲线和极限承载力进行了系统分析。结果表明:设计的柔性连接满足墙板承载力要求;墙板连接节点的位置和个数对墙板开裂荷载、挠度、极限抗弯承载力和破坏状态影响显著;开窗洞墙板由于配筋加密,刚度增强,削弱了开洞对墙板承载的不利影响。各墙板在正常使用极限荷载下均未破坏,挠度满足规范要求。     

钢管混凝土加劲环管板节点受力性能研究

为研究钢管混凝土加劲环管板节点在轴向拉力作用下的受力性能,开展了3个节点试件的单调加载试验,分别得到了管板节点加强前后的荷载-位移曲线和破坏模式。试验结果表明：SPR节点在单调荷载作用下主管和加劲环发生局部屈曲,表现为延性破坏;CFT节点在荷载作用下主管壁发生剪切破坏,荷载-位移曲线没有明显的屈服段,表现为脆性破坏;CFTR节点在荷载作用下,连接板处加劲环发生剪切破坏,同时加劲环局部V形屈曲;加劲环能够明显提高管板节点的承载力,同时改善节点的塑性性能;相较于主管外设加劲环,主管内部填充混凝土具有更好的承载力提升效果,节点的刚度变大但塑性性能变差;钢管混凝土加劲环管板节点具有加劲环和混凝土的双重特性,在显著提高节点承载力的同时保障节点塑性性能。在264个有限元模型参数分析的基础上,得到了双加劲环管板节点受拉承载力的计算方法,给出了加劲环厚度和宽度组合的设计建议。基于极限分析的塑性铰线方法,推导出SP节点和SPR节点极限承载力的理论计算模型,计算结果与有限元结果吻合较好。     

多螺栓连接薄壁板件抗剪(荷载-挠度)性能

对多螺栓连接薄壁板件的抗剪性能进行了数值分析。采用有限元模型对一系列复杂的参数进行分析,研究不同的设计参数对连接板件性能(包括初始刚度、极限承载力以及极限承载力状态下的最大挠度)的影响。设计参数包括:边界条件、约束条件、螺栓间距、沿加载方向和垂直于加载方向的螺栓数量以及钢材的断裂伸长率限值。结果表明:现有计算刚度和极限承载力的方法是可行的。研究重点在于极限状态下板件最大挠度。基于参数分析结果,发现了不同失效模式下螺栓孔周边的应变分布,表明作者所提出的单螺栓连接板件的应变分布仍然适用,但需要修改板件的尺寸范围,包括用于辨识不同螺栓排列下失效模式差异的应变分布。     

鞍板和环板加劲K形相贯节点承载力试验研究

为研究采用节点板、鞍板、环板加劲的K形相贯节点的受力特性,设计并制作了11个节点试件开展比例加载试验研究,得到其变形、应力分布及破坏模式等受力性能。利用经试验验证的有限元模型,分析了加劲组件和钢管参数对该类加劲相贯节点承载力的影响,并给出了受荷节点的力学模型。有限元分析和试验结果表明,该节点表现出无加劲相贯节点和带鞍板的管-板节点的受力特征,加劲构造能有效提高节点承载力。参数敏感性分析结果表明,增加支管和主管直径比、主管厚度、节点板长度和扇形鞍板圆心角可提高节点极限承载力。给出了极限承载力简化计算方法,计算结果和有限元分析及试验结果吻合较好。     

输电塔交叉斜材承载力试验及有限元分析

本文设计了输电铁塔常用的两种交叉斜材节间,根据斜材不同的内力比值共完成12组静力加载试验。采用有限元软件ANSYS对两种节间进行数值分析,并将分析结果与试验结果及规范计算结果进行对比分析。建立了螺栓连接节点的有限元模型,得到了螺栓节点连接滑移的荷载-位移曲线。然后根据荷载-位移曲线建立交叉斜材滑移模型,并在验证模型有效性的基础上进行参数分析。研究表明,交叉斜材节间极限承载力受拉压比影响,现有规范中的计算方法对于交叉斜材节间有一定偏差。本文提出的考虑螺栓滑移的ANSYS模型能够较好地模拟交叉斜材节间的破坏形式,并算得较为精确的极限承载力,通过参数分析发现材料强度、长细比、宽厚比对于交叉斜材节间极限承载力产生影响。     

开洞加劲钢板剪力墙的力学性能研究

针对深圳梅山苑7号楼钢板剪力墙上开洞问题,对开洞闭口加劲钢板剪力墙进行了有限元研究,给出了不同开洞位置和不同开洞率钢板剪力墙荷载-侧移曲线,分析了开洞位置和开洞率对初始刚度、屈曲荷载和极限荷载的影响.研究表明,中间开洞对钢板剪力墙刚度和极限承载力影响较大,可以采用线性公式计算开洞对钢板剪力墙初始刚度、屈曲荷载和极限荷载的折减.     

不同螺栓边距对角钢连接性能影响的研究

角钢在土木工程中应用广泛。为研究不同螺栓边距对角钢连接性能的影响,设计了角钢在不同螺栓边距下的连接试验,通过改变螺栓孔边距研究角钢螺栓连接的抗剪性能,建立ABAQUS有限元模型与试验结果对比验证。并运用有限元建模方法,改变角钢型号进行参数分析。结果表明,有限元分析的荷载-位移曲线、极限承载力和破坏模式与试验结果吻合较好,为做参数分析提供依据;对《钢结构设计手册》中螺栓边距进行修正,便于实际工程应用。     

肋板加强式新型工字形柱弱轴连接的抗震性能有限元分析

基于一种新型节点域箱形加强式工字形柱弱轴连接的研究成果,进行梁端肋板加强式节点抗震性能的研究。利用有限元软件ABAQUS对模型进行非线性分析,得出节点的破坏形态和焊缝等关键部位的应力分布情况。通过计算得出荷载-位移曲线、骨架曲线、极限承载力、位移延性等节点参数,并对其延性及耗能能力与标准新型弱轴连接试件进行对比分析。研究结果表明:肋板加强式弱轴连接节点能够有效地迫使梁端塑性铰外移,从而实现"强柱弱梁"的抗震理念。肋板加强可以改善新型弱轴连接梁柱翼缘对接焊缝和蒙皮板的应力分布并提高节点的刚度和承载力,具有较标准新型弱轴连接更好的抗震性能。     

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.     

Load–deflection behaviour of thin-walled plates with a single bolt in shearing

This paper presents an experimental, numerical and analytical study of the behaviour of thin-walled plates connected by a single bolt under shear. Eighteen tests were carried out to provide detailed data of load–deflection and load–strain curves for validation of the finite element simulation model. The validated finite element model was then used to perform a comprehensive set of parametric studies to investigate the effects of different design parameters on the connected plate behaviour, including initial stiffness, ultimate resistance and maximum deformation at the ultimate resistance. It was found that the stiffness and ultimate resistance could be predicted accurately by using existing methods. The analytical study therefore focused on developing a method to calculate the maximum plate deformation (hole elongation) at the ultimate resistance. Based on the parametric study results, methods of calculating the ultimate deformation were proposed, based on different failure modes of the connection.     

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.     

火灾中采用逆向通道连接的钢梁-钢管混凝土柱结构约束组件的数值模拟

利用有限元软件ABAQUS,采用三维块单元,模拟火灾中钢梁-钢管混凝土柱及其节点约束组件的性能。利用近期英国曼彻斯特大学的采用逆向通道连接的3组耐火试验,对模型进行验证。结果表明:有限元模型能成功进行模拟。利用有限元模型,初步研究改变连接构件以加强结构耐火能力的可行性。对连接方式进行改进,以期使连接梁的链式反应能更好发展。提出外伸-内缩式混合端板连接形式,连接的拉伸部分采用外伸端板,以提高延性;受压部分采用内缩式端板,提高韧性。结果表明:不需任何费用,只要用混合端板连接替代外伸端板连接,就能提高连接梁的耐火能力。     

Ultimate strength of bolted moment-connections between cold-formed steel members

The behaviour and design of bolted moment-connections between cold-formed steel members, formed by using brackets bolted to the webs of the section, is considered. The particular problem of the moment-capacity of such joints being lower than that of the cold-formed steel sections being connected because of web buckling, caused by the concentration of load transfer from the bolts, is addressed. In this paper, a combination of laboratory tests and finite element analyses is used to investigate this mode of failure. It is demonstrated that there is good agreement between the measured ultimate moment-capacity and that predicted by using the finite element method. A parametric study conducted using the finite element model shows that the moment-capacity of a practical size joint can be up to 20% lower than that of the cold-formed steel sections being connected. Web buckling so-caused must therefore be considered in the design of such connections.     

A finite element analysis model for the behaviour of cold-formed steel members

A finite element analysis model for the post-local buckling behaviour of cold-formed steel (CFS) members subjected to axial compression has been developed. The finite element model consists of a Total Lagrangian nonlinear 9-node “assumed strain” shell finite element, and experimental-based material properties models to represent the body of the CFS sections. Experimentally derived residual stress variations, and initial geometric imperfections have also been incorporated. A special loading technique and a displacement solution algorithm were employed to obtain a uniform displacement condition at the loading edges. Details of a test program involving 20 non-perforated, and perforated cold-formed stub-column steel sections have been presented in the second part of the paper. The comparison between the test results, and the finite element results was performed for axial and lateral displacement behaviour, buckling loads, ultimate loads, and axial stress distribution. The comparison forms the basis for the evaluation of the efficiency, and the accuracy of the finite element model, and it indicated that the finite element analysis model constructed herein gives accurate and consistent results for the behaviour of the cold-formed steel members subjected to axial compression.     

基于三维有限元分析的半刚性组合连接参数研究

采用三维有限元模型模拟钢梁和预制中空楼板的组合连接。该模型模拟了组合梁的结构特性,为更好地理解结构特性,尤其是连接处的弯矩转动特性,该模型同时也被用于研究大量范围内的组合连接件的特性。在对结构行为的研究中采用了多种参数:梁的尺寸、末端厚度、柱网密度、预制中空楼板的进深以及螺栓间距。通过对参数的研究,详细讨论了组合连接构件的结构行为,并且为设计提出了建议。     

Evaluation of connection flexibility in cold formed steel racks

Steel storage racks are three-dimensional framed structures fabricated from cold formed steel sections, wherein hook-in end connectors are used to make beam-column connections which are basically boltless and semi-rigid in nature. Different types of beam end connectors with different geometry of the connected members are available, making it impossible to develop a generalized analytical model. Only very few theoretical models are available to evaluate the performance of the joints for some typical connectors. More often experimental evaluation and numerical studies are needed to predict the behaviour of every different type of connectors. In the present study eighteen experiments were conducted on a commercially available pallet rack connection by varying the most influencing parameters such as thickness of the column, depth of the connector and the depth of the beam. The main objective of this work is to quantify the beam to column joint, flexibility of commonly used pallet rack frame and to develop a general Frye-Morris type/three parameter power model type moment versus relative rotation relationship. A companion finite element shell model that simulates the experimental behaviour closely is developed using ABAQUS finite element software, which is also used for further parametric studies. Using the three major variables as size parameters, a Frye-Morris type of equation has been proposed. Some calibration studies have also been carried out. Using the ultimate moment capacity, initial connection stiffness and the shape parameter obtained, a three parameter power model has also been proposed to represent the moment-rotation behaviour of the boltless connections.     

Earthquake analysis of reinorced concrete minarets using ambient vibration test results

This paper describes a Turkish style reinforced concrete minaret, its finite element model, modal testing, finite element model updating and earthquake behaviour, before and after model updating. The minaret of a mosque located in Trabzon, Turkey is selected as an application. A three‐dimensional (3D) model of the minaret and its modal analysis is performed to obtain analytical frequencies and mode shapes using ANSYS finite element program. The ambient vibration tests are conducted on the minaret under natural excitations such as wind effects and human movement. The output‐only modal parameter identification is carried out by Enhanced Frequency Domain Decomposition and Stochastic Subspace Identification methods in Operational Modal Analysis software and in doing so, dynamic characteristics (natural frequencies, mode shapes and damping ratios) are determined. A 3D finite element model of the minaret is updated to minimize the differences between analytical and experimental modal properties by changing some uncertain modelling parameters such as material properties and boundary conditions. The earthquake behaviour of the minaret is investigated using 1992 Erzincan earthquake before and after finite element model updating. Maximum differences in the natural frequencies are reduced from 21% to 8%, and good agreement is found between analytical and experimental natural frequencies. In addition to this, it is realized that finite element model updating is effective on the earthquake behaviour of the minaret. Copyright © 2008 John Wiley & Sons, Ltd.     

Finite element modelling of plate girders with web openings

This paper is concerned with a finite element model to predict the behaviour and ultimate load of plate girders with web openings. The finite element package is used to model the plate girders with web openings. Accuracy of the model is assessed by applying it to plate girders tested earlier by other researchers. Comparison of analytical results with the available experimental results for yielding patterns, ultimate load values and load–deflection relationships show good agreement between the finite element and experimental results thus validating the accuracy of the proposed model. The proposed finite element method was extended to carry out a parametric study. The study covered parameters such as web slenderness and flange stiffness.