组合桁架节点的试验及有限元分析

采用模拟试验及有限元方法,对某桁架斜拉桥中组合节点的力学性能进行分析。试验研究了此节点的安全裕度及适用性,模型缩尺比例为1:2.5。分析了应力分布、裂缝抵抗能力、锚栓剪切抵抗力,研究了节点的力学性能及传力途径。在荷载达到设计荷载的1.7倍前,钢板和混凝土弦杆的最大应变均在弹性范围内,说明这种结构有很好的安全裕度。基于试验结果,建立三维有限元模型,有限元分析的承载力和刚度计算结果与试验吻合较好。本分析为后续研究及组合桁架桥、组合节点的设计,提供了有价值的参考。     

Model test and numerical analysis of a special joint for a truss bridge

This paper presents a study on the mechanical behaviours of a special joint between a rigid suspension cable and a truss girder in a rigid suspension stiffened steel truss bridge. Both a model test and a numerical finite element analysis (FEA) have been conducted, and relevant information about the models used, loading procedure and test scheme is presented. The model test shows that the maximum stress in the joint is less than the material allowable stress and the maximal stress induced from the secondary moment accounts for about 30% of the total stress. A three-dimensional finite element model is used in the numerical analysis and the results are in very good agreement with those of the model test. This study shows that the design of the special joint is reasonable and the structure safe. It is also expected that the results presented in this paper would be useful as references for future research and design of rigid suspension stiffened steel truss bridges and joints.     

复杂空间桁架节点抗震性能试验研究及有限元分析

桁架转换层被广泛应用于高层建筑中,以实现结构形式的垂直转换,多榀桁架交界处的节点,其受力性能对整个桁架的安全性影响较大。结合工程实例,对上海市长宁来福士广场东部裙房桁架转换层中的两处复杂节点进行1∶4缩尺模型试验和有限元分析,研究了节点的承载力、应变发展、受力性能和破坏模式。试验结果和有限元分析表明：节点具有较高的承载力和良好的耗能能力,满足设计要求;节点腹杆板件端部的尺寸放大,改善了腹杆的轴向传力,降低了应力集中。节点的薄弱部位位于型钢混凝土柱与弦杆翼缘的交界处,节点发生破坏时,弦杆和腹杆基本没有进入屈服状态。     

基于效率系数的组合钢桁梁优化设计方法

组合钢桁梁具有桁架结构的受力特征,同时还受节点性能和板桁组合作用的影响,受力机理复杂。传统有限元优化方法无法兼顾杆件和节点,为对组合钢桁梁设计方案进行快速、准确地优化,提出了一种基于效率系数的优化设计方法。在采用杆系有限元模型进行初步分析基础上,根据结构内力分布相似的假定,以杆件和节点承载力效率系数为优化指标对构件进行优化,再将优化方案代入有限元模型进行验证。以矩形钢管混凝土组合桁梁连续梁桥既有通用图集为依托工程,进行设计方案优化。结果表明:组合钢桁梁空间效应等因素产生的弯曲应力可达组合应力的15%～42%,弯矩产生的影响不可忽略,在计算杆件效率系数时应将弯矩和轴力同时考虑在内; 效率系数可直观反映组合钢桁梁构件应力状态,快速定位优化构件,还可依据杆件截面特征将优化方案细分至板件层面; 所提优化设计方法可对组合钢桁梁的节点和杆件进行统筹优化,避免反复进行有限元试算,显著提高优化计算效率。     

一种钢-混组合桁架桥下弦杆节点极限承载力研究

钢-混组合桁架是一种新型铁路桥梁结构,节点受力复杂,通过对3个采用PBL连接件的钢-混组合桁架节点进行水平单调加载试验,研究了外接式节点的受力特性、破坏模式和极限承载力。基于有限元软件ABAQUS对试件进行3D模型分析,计算结果与试验结果较为吻合。研究表明：钢-混组合桁架节点受力性能良好,PBL连接件传力效果明显;钢腹杆为节点薄弱环节,增加腹杆厚度可有效提高节点屈服后强度和节点极限承载力;通过模型分析,提出的腹杆不对称的设计方法,破坏顺序明确,与3个钢-混组合桁架节点的试验结果相比偏于安全,能够满足我国桥梁抗震设计要求。研究成果可为同类节点的应用提供参考。     

型钢再生混凝土柱-钢梁组合框架节点受力性能非线性分析

在型钢再生混凝土柱-钢梁组合框架节点拟静力试验基础上,采用ABAQUS有限元软件建立了组合框架节点的数值计算模型,对该组合框架节点在水平荷载作用下的受力非线性行为进行了有限元分析,获取了组合框架节点的破坏过程、破坏形态、应力云图、荷载-位移曲线及荷载特征值,并对节点的承载力计算值与试验值进行了比较,验证了有限元计算模型的合理性,进而分析了有限元拓展参数对组合框架节点受力性能的影响规律。结果表明:有限元计算结果与试验结果吻合较好,该有限元模型能较好地模拟该组合框架节点在水平荷载作用下的受力性能;另外,提高再生混凝土强度或者箍筋强度对组合框架节点的抗剪承载力是有利的,但节点的延性变形能力有所降低;组合框架节点的抗剪承载力随着型钢强度的提高而显著增加,但节点的变形能力变化不大;增加体积配箍率或型钢配钢率可以明显提高组合框架节点的抗剪承载力和变形能力。     

随州南站新型分叉节点受力性能试验研究

随州南站的树状结构采用一种新型非铸钢的分叉节点。此类分叉节点外形不规则、受力复杂。为研究此新型分叉节点在最不利设计工况下的受力性能,并验证其安全性和合理性,对节点进行有限元分析和足尺试验研究。节点模型的试验值与有限元分析结果吻合良好,表明此节点有限元模型能真实模拟节点模型的边界条件和受力状态。试验结果表明:足尺节点能够满足设计承载力要求;在1.3倍设计荷载作用下,节点主肢角部出现塑性发展区。根据分析结果对分叉节点设计进行改进,提高节点的安全冗余度。该新型分叉节点具有较高的安全储备。     

大跨度钢-混凝土组合桁架铁路桥端节点模型试验研究

钢-混凝土组合桁架梁上弦端节点受力复杂,有必要通过模型试验对其钢-混上弦节点的应力应变状态及工作性能进行研究,探索组合桁架上弦节点合理构造和承载力。介绍节点模型的设计、加载过程和测点布置等;重点通过对试验结果分析和有限元计算的比较,得出弦杆应变和节点板应力的分布规律,通过绘制弦杆荷载-水平位移曲线,对节点的非线性受力行为进行研究,得出节点整体的受力性能。研究表明:钢-混凝土组合桁架节点受力合理,节点承载力安全储备较高,满足铁路桥梁设计要求,PBL连接件抗剪能力良好;节点板是受力的关键部位,加设节点板加劲肋可以有效提高节点屈服后强度,但对极限荷载的提高作用不大。     

天津奥林匹克中心体育场铸钢节点试验研究

天津奥林匹克中心体育场大跨度钢管桁架结构铸钢节点受力和构造复杂,为考察铸钢节点的受力性能,评价其安全性,对铸钢节点进行了足尺试验和有限元计算分析。首先建立节点有限元实体模型进行有限元计算分析;根据有限元计算结果,布置应变测点,对节点进行设计荷载作用下的试验,得到节点应力试验值。结合试验结果与有限元计算结果,分析了节点的应力分布规律,表明天津奥林匹克中心体育场铸钢节点具有较高的承载性能和足够的安全性。     

Experimental and numerical analysis of a halved and tabled traditional timber scarf joint

Traditionally constructed heavy timber trusses, found in timber framed buildings and bridges, employ various traditional joints, among them the lower chord scarf joint. This paper examines the behavior of a halved and tabled scarf joint, which was studied as an isolated structural component using experimental tests and finite element analyses. Experimental tests identified two different limit states for these particular scarf joints: shear failure parallel to grain and tension failure perpendicular to grain. The possibility of failure due to tension perpendicular to grain results from variations in grain angle and means that the limit state of shear failure parallel to grain, typically assumed in analysis and design, is unconservative. For the purposes of design and rehabilitation, the authors propose that the scarf joint be treated as a member subject to combined bending and axial tension forces. The results of the finite element analysis, performed using solid continuum elements in ABAQUS, are in good agreement with the experimental test results. In addition to finite element models, the authors use analytical spring models to demonstrate that when developing a two-dimensional model of a truss with lower chord scarf joints, serviceability limit states be checked with a model that reduces the lower chord section properties in the vicinity of the scarf joints.     

45m跨度组合楼盖典型节点的设计及有限元分析

通过对一种新型的超规范大跨度钢桁架-混凝土组合楼盖的典型复杂节点进行设计和有限元分析,在规范推荐的节点构造基础上提出了一种新型的用于大跨度组合楼盖的节点构造形式,有限元分析结果表明:此种节点构造形式具有良好的受力性能和足够的安全度.     

空间足尺组合式连接节点受力性能研究

以某大型特高压用钢管格构式变电构架工程为背景,对空间足尺组合式连接节点进行空间静力加载试验和有限元分析,着重研究节点的应力应变及位移发展特征、破坏模式和极限承载性能。试验结果表明:设计荷载下,除主管与节点板连接处的端部由于应力集中而出现轻微局部屈服外,节点其他部位仍处于弹性阶段|加载至设计荷载的近190%时,主管受力较大端出现受压“鼓曲”,主管与节点板1（JDB1）的连接处严重“凹陷”,随即支管⑦的插板与JDB1连接处发生受压“失稳”,节点破坏。有限元模型的分析结果,在节点应变发展、荷载-位移曲线、破坏模式、极限承载力等方面均与试验结果吻合较好。该类型节点的构造基本合理,满足设计荷载要求。建立节点承载力的理论分析模型及计算公式,理论计算结果与试验结果、有限元分析结果吻合较好。     

The effects of partial shear connection in composite flush end plate joints Part II—Analytical study and design appraisal

The behaviour of composite beams under hogging bending has been successfully simulated using an analytical model derived previously. This paper describes the extension of the work to study the behaviour of composite joints incorporating semi-rigid flush end plate connections. With proper inclusion of the joint characteristics, the model was found to be equally capable of modelling the structural behaviour including the effects of partial shear connection. Experimental results of a novel series of composite joint tests detailed in the accompanying companion paper were compared, in addition to those published in the literature. The analysis results provided close agreement with the various test behaviour. Using the model that has been properly calibrated against experimental results, a systematic parametric study was also undertaken. The outcomes are described herein. In addition, existing design models to predict the strength, stiffness, and ductility of composite joints were also reviewed and compared against the test results. The results emanating from this paper contribute as a total package apart from experimental undertakings to further understand the complex behaviour of the composite joints. This is very beneficial in a design perspective.     

错位交汇型钢管焊接节点试验研究

厦门火车西站站台雨棚钢结构节点为钢管焊接的空间管桁节点,其中存在一种杆件错位交汇的特殊节点形式.由于此种节点并非所有杆件交汇于同一点,杆件错位交汇使得节点受到较大偏心力的影响,加上节点杆件较多,受力状态较为复杂.为确保其安全性,选择其中典型的KT-KTT型节点进行足尺试验研究和弹塑性有限元分析.试验结果表明,节点承载力...     

复合材料拉挤型材桁架桥静载性能试验研究

采用以拉挤成型工艺制成的复合材料方管及片材装配成的轻质复合材料桁架桥,具有质量轻、强度高、可工业化生产、拼装迅速、耐腐蚀性强、免维护的显著优点。本文通过对复合材料桁架桥整体结构进行竖向静载试验,研究桥梁整体的协调变形能力和杆件连接的效果,分析复合材料桁架桥在荷载作用下结构竖向位移、杆件应力等。基于桁架桥梁静载性能试验结果,统筹考虑复合材料杆件受拉、受压,节点断裂等破坏特征。研究结果表明:轻质复合材料桁架桥具有较高的刚度和承载能力,在102.86%的设计荷载作用下结构变形为22.23 mm,同时通过有限元软件MIDAS,对承受荷载的复合材料桁架桥进行了有限元模拟计算,有限元分析与试验结果较吻合。     

The influence of joints and composite floor slabs on effective tying of steel structures in preventing progressive collapse

The event of the terrorist attack on 11th September 2001 in the USA has attracted increasing attention of researchers and engineers on progressive collapse of structures. It has gradually become a general practice for engineers to consider progressive collapse resistance in their design. In this paper, progressive collapse of steel frames with composite floor slabs is simulated by the finite element method. The numerical results are compared with test results. The influence of the joints and the concrete slabs on the effective tying of steel beams is investigated through parametric studies. From the analysis, methods of preventing progressive collapse that can be considered in design and when retrofitting existing structures are proposed. The results show that retrofitting a structure with pre-stressed steel cables and an increase of crack resistance in the concrete near joints can effectively improve effective tying of a structure, which results in an enhanced structural capacity in preventing progressive collapse.     

单向复合材料单搭接粘结节点的破坏预测及增强

提出了一种预测复合材料单搭接粘结节点在复合材料本体和粘结界面上破坏的方法。该方法采用了粘结剂和分层破坏判断的一个完全弹塑性模型,采用有限元方法和本文方法进行破坏预测。预测结果显示：破坏模式和强度都与各种粘结方法和参数下进行的节点模型试验结果吻合很好。基于数值分析,建立最佳节点强度条件,并提出一种新的提高节点强度的方法。验证结果表明：该方法可显著提高节点强度。     

Testing of composite steel top-and-seat-and-web angle joints at ambient and elevated temperatures, Part 1: Ambient tests

This paper presents six ambient tests on composite steel top-and-seat-and-web (TSW) angle joint specimens subject to monotonic loading. It is well known that the inherent strength and stiffness of composite semi-rigid joints can improve the structural behaviour of steel frame structures. However, experimental works on the composite steel TSW angle joints are very limited. The main objective of this study is to ascertain the ambient moment-rotation characteristics of composite steel TSW angle joints and to validate the authors’ mechanical model. The test results are presented and the joint failure modes are described. The effects of some parameters on the overall joint behaviour, such as longitudinal shear strengths of RC slabs, steel beam depths and tightening torques of bolts are investigated. With the development of a new joint component to represent the RC slab in tension, the authors’ mechanical model proves to be able to produce accurate and consistent predictions of the moment-rotation characteristics of composite steel TSW angle joints. The analytical results are compared with the test results and good agreement is achieved.     

全T型钢桁架承载力及节点性能的试验研究

通过对两种节点形式下的全T型钢桁架承载力的试验研究,分析桁架承载力的理论计算依据,并借助有限元分析软件对桁架节点进行应力分析。对试验值与有限元计算值进行对比,验证有限元软件分析全T型钢节点的适用条件,分析节点的受力性能的特征及优越性,为推广T型钢在桁架中的应用提供依据。     

广州体育馆屋盖辐射桁架上下弦节点试验与节点设计

广州体育馆屋盖辐射桁架上弦节点采用K型、T型的方钢管与圆钢管的直接焊接相贯节点 ,下弦采用垂直腹杆下端实心钢棒与钢管焊接。介绍上下弦节点的试验情况、有限元分析及节点设计