偏心移动荷载对焊接钢吊车梁上部区域裂缝的影响

通过3 根模型梁试验,研究了带裂缝焊接钢吊车梁在偏心移动荷载作用下腹板上部裂缝区域的应力分布及应力变化规律,提出腹板上部主剪应力及主拉应力的循环作用是服役吊车梁裂缝继续发展的主要原因     

焊接钢吊车梁上部区域裂缝的形成与发展

通过3根模型梁试验,研究了带裂缝焊接钢吊车梁在偏心集中荷载作用下,上部区域的应力分布及应力变化规律,提出了偏心集中荷载在腹板上部产生的局部附加应力是导致吊车梁上部区域裂缝形成与开展的主要原因.     

Theoretical and experimental investigation of the collapse behaviour of transversely stiffened aluminium alloy plate girders

This paper reports on part of an ongoing research programme into the collapse behaviour of lightweight aluminium girders, suitable for transportable bridging systems. It describes the theoretical and experimental investigation of the behaviour of the transverse web stiffeners of welded aluminium alloy plate girders loaded predominantly in shear. The theory is based on a mathematical model that assumes a non-linear shear stress distribution at the boudaries of the adjacent web panels. The experimental investigation consists of a series of tests in which 10 fabricated plate girders were loaded to failure; careful tests of material properties are also reported.     

基于移动控制力模型的轨道梁动力特性初步研究

磁浮轨道梁动力特性是磁浮关键技术研究中的重要内容,该方面的研究一直以来备受结构工程界的关注。结合已有研究成果,建立了悬浮模块与轨道梁动力相互作用模型,考虑主动控制的电磁力特性,对一系列悬浮模块在轨道梁上移动引起的动力响应进行数值仿真计算,分析了轨道梁阻尼比、跨数、重量和列车运行速度对轨道梁变形特性的影响规律。分析结果表明:结构阻尼对梁系统动力特性影响较小;基频不变的条件下,简支梁质量变化对梁动力系数的影响很小;随着速度提高,冲击系数总体上呈波动上升趋势,但在正常运行速度下并未出现明显的共振现象。本文的研究结论为轨道梁合理设计参数的选取提供了理论依据。     

焊接钢吊车梁裂缝发展机理的试验研究

通过 3根模型梁试验及有限元分析 ,研究了焊接钢吊车梁在偏心集中荷载作用下 ,裂缝区域应力分布规律 ,提出吊车梁腹板剪应力和主拉应力分别循环是导致裂缝扩展的根源     

The collapse of welded aluminium plate girders—an experimental study

Twenty-two tests conducted to study the collapse behaviour of welded aluminium girders are described. The girders are of varying proportions, have transverse or longitudinal web stiffeners and are subjected to different combinations of shear and bending loads. It is observed that, although shear sway mechanisms similar to those for steel girders do develop, the webs of aluminium girders may fracture in the heat affected zones adjacent to the perimeter welds. These fractures develop at some stage during the formation of the collapse mechanism and are the consequence, rather than the cause, of failure. It is shown that the tension field theory, originally developed for steel girders, may overestimate the shear-carrying capacity of aluminium girders and it is concluded that the theory requires some modification before it can be applied with confidence to aluminium girders.     

浅议附加横向钢筋的设置问题

该文阐述了附加横向钢筋的设置作用、原因及计算方法,通过分析比较"主次梁搭接"与"梁上托柱"的两种情况下集中荷载对主梁产生的影响,得出"梁上托柱"结构设计时不需要设置附加横向钢筋。     

小跨高比混凝土简支箱梁静力性能试验研究

山地城市排水干管埋地箱涵由于滑坡导致地基塌陷而成为简支箱涵,支承方式的改变导致管道结构存在破坏风险.为此,文章对简支下小跨高比埋地箱梁进行了模型静力加载试验,分析了小跨高比埋地箱涵在简支条件下的破坏形式、抗剪性能以及剪力滞效应,讨论了现行有关设计规范对于箱涵抗剪承载力计算之不足.研究表明,竖向均布荷载作用下,小跨高比箱...     

Experimental and analytical studies on bearing capacity of bolt connected composite plate girders

Composite plate girders bearing the enormous concentrated loads from boilers are common members in thermal power plants. Because of their large scale and sustaining distinct loads, the section of these girders is made of two parts combined with high strength bolts. Experimental investigations on two I-section plate girders, two homogeneous composite girders, and two hybrid composite girders, are implemented. Bearing capacity and member ductility are compared among the three kinds of specimens. To reveal the mechanism of composite plate girders, force method built upon the linear elastic theory is employed, according to deformation coordination among the components. The elastic stress distribution predicted by the analytical method is validated against test data. Based on the internal force distribution derived, the elastic effective width method in current specifications and the plastic effective width method proposed in other published literature are employed herein to predict the critical load. Conclusions can be made that bearing capacity of composite girders is superior to the I-section ones, and hybrid composite plate girders can further balance the economic and mechanical efficiency of constructions. Additionally, several proposals for application are offered.     

Der Einfluss von Zwischenhölzern auf das Biegedrillknickverhalten zweiteiliger Brettschichtholzträger

The influence of intermediate links on the lateral torsional buckling of two‐part glued laminated girders. The lateral torsional buckling behaviour of two‐part laminated girders can be influenced very advantageously by means of intermediate links. The reason for it represents mainly the shearing connecting of the two elements in their longitudinal direction. Furthermore the intermediate links cause an elastic torsional coupling which is the reason why the lateral torsional buckling of the single parts of the girder also is determined by vertical displacements besides the usual torsions and horizontal displacements which require further deformation energy. In this paper the bifurcation loads are determined for a girder with different types of the intermediate links by means of a finite element analysis. In addition nonlinear elasticity calculations according to theory of second order are carried out to get the forces and moments of the links. The results of the investigations demonstrate that connections between the two parts of the girder are the reason that the buckling loads rise significantly. The arithmetical consideration of the connections at the supports alone shows already very positive consequences on the buckling behaviour of the girder.     

局部火灾下钢框架中上翼缘无侧移工字梁的极限状态计算

本文根据钢框架中工字梁在梁下局部火灾下将产生较大温度轴压力，其受力状态发生改变的事实，建立了钢框架中上器无侧移工字形梁的下器侧移失稳挠曲微分方程，应用能量法近似求解获得了验算梁下翼缘侧向稳定的计算长度，并结合我国现行钢结构设计规范建立了梁下翼侧移失稳的极限状态方程。此外，本文还建立了局部火灾下梁形成三铰机构而破坏的极限状态方程。这两个极限状态方程可直接用于钢框架工字梁的抗火设计与计算。     

Innovative steel-UHPC composite bridge girders for long-span bridges

Steel and steel-concrete composite girders are two types of girders commonly used for long-span bridges. However, practice has shown that the two types of girders have some drawbacks. For steel girders, the orthotropic steel deck (OSD) is vulnerable to fatigue cracking and the asphalt overlay is susceptible to damage such as rutting and pot holes. While for steel-concrete composite girders, the concrete deck is generally thick and heavy, and the deck is prone to cracking because of its low tensile strength and high creep. Thus, to improve the serviceability and durability of girders for long-span bridges, three new types of steel-UHPC lightweight composite bridge girders are proposed, where UHPC denotes ultra-high performance concrete. The first two types consist of an OSD and a thin UHPC layer while the third type consists of a steel beam and a UHPC waffle deck. Due to excellent mechanical behaviors and impressive durability of UHPC, the steel-UHPC composite girders have the advantages of light weight, high strength, low creep coefficient, low risk of cracking, and excellent durability, making them competitive alternatives for long-span bridges. To date, the proposed steel-UHPC composite girders have been applied to 14 real bridges in China. It is expected that the application of the new steel-UHPC composite girders on long-span bridges will have a promising future.     

横向弯曲波折腹板组合板梁研究

采用LUSAS程序进行有限元分析,研究了横向弯曲波折腹板组合板梁的极限承载力和力学性能,分析了腹板开孔面积对该梁承载力和力学性能的影响。影响该梁力学性能的主要参数有:腹板长细比d/t、腹板长宽比b/d、波折宽深比bh/h及孔尺寸,分析这些参数对结构倒塌性能的影响。分析得出了组合板梁的极限承载力、破坏机理及荷载-位移曲线,并列出了一些典型结果。提出了该梁剪切承载力的近似计算方法,并利用有限元结果,验证该方法的准确性。     

高性能钢梁混杂设计方法及整体稳定性分析

阐述高性能钢梁的混杂设计概念,通过必要实例说明高性能混杂钢梁的优点,并运用ANSYS有限元程序,分析焊接H型混杂简支梁在跨中集中荷载作用下的整体稳定性。     

非规则梁桥纵向地震反应及碰撞效应

针对我国西部山区典型的非规则梁式桥梁 ,采用非线性时程地震反应分析方法 ,探讨了纵向地震作用下非规则梁桥相邻联的非同向振动特性和伸缩缝处的碰撞效应。结果表明 :当梁式桥相邻联周期相差较大时 ,纵向地震作用下 ,会导致伸缩缝处相邻梁体较大的相对位移和碰撞 ,碰撞导致低墩地震反应增大 ,对结构抗震不利。还提出了减小相邻联非同向振动和伸缩缝处碰撞效应的措施和方法     

Transversally stiffened plate girders subjected to patch loading. Part 1. Preliminary study

In this paper, an experimental programme of six steel plate girders subjected to patch loading as well as results of forty eight numerically-tested prototypes are presented. Results of ultimate load capacity as well as structural responses from these girders are provided. In addition, experimental and numerical values of ultimate load capacity are compared with those predicted by EN1993-1–5. With such results, the response of transversally stiffened steel plate girders is discussed throughout the paper. Particular emphasis is given to the influence of the transverse stiffening on the ultimate load capacity of the girders. It is observed that girders with largely spaced transverse stiffeners present a considerably different response from girders with closely spaced transverse stiffeners. The structural response for the former case has been thoroughly studied in the last decades whereas little attention has been paid for the latter. Further analysis of this particular topic is provided in a companion paper.     

The influence of longitudinal web stiffeners upon the collapse behaviour of plate girders

This paper describes eighteen tests carried out to study the influence of longitudinal web stiffeners upon the collapse behaviour of plate girders. The results of tests in which the stiffeners proved adequate are compared with those involving inadequate stiffeners and with tests on unstiffened girders. It is observed that, whereas girders with adequate stiffeners, in common with unstiffened girders, develop a stable failure mechanism, girders with inadequate stiffeners show a sharp drop from the maximum load, followed by the formation of a failure plateau at a reduced load level. Ultimate load capacities predicted by a tension field mechanism approach show satisfactory agreement with experimental values and current British and American design proposals are observed to provide conservative estimates of capacity.     

Hybrid steel plate girders subjected to patch loading, Part 2: Design proposal

The resistance of plate girders subjected to patch loading has been studied thoroughly for the case of homogenous girders. The particular case of hybrid girders has been generally treated identically than for homogenous specimens. In this paper, the current EN1993-1-5 formulation is evaluated and some peculiarities concerning the treatment of hybrid girders subjected to patch loading are pinpointed. It is numerically demonstrated that the moment capacity of the flanges does not play any role in the resistance of plate girders to patch loading as predicted in EN1993-1-5. Accordingly, a design proposal which corrects the current EN1993-1-5 formulation is presented at the end of the paper.     

厦门日圆大桥钢管拱整体吊装施工工艺

厦门环湖里大道日圆大桥为结构新颖的钢管拱—连续预应力混凝土箱梁组合体系,其钢管拱吊装是主桥施工的关键。着重介绍了钢管拱吊装的施工工艺。     

Investigation on the Collapse Behavior of Diagonal Stiffened Composite Plate Girders Subjected to Shear Loading

In this study, a new analytical method is presented to estimate the shear capacity of diagonally stiffened steel–concrete composite plate girders. This method is formulated based on tension field action in steel girder web and failure mechanism of concrete slab deck. To validate the accuracy of the proposed method, the obtained results are compared with three-dimensional finite element analysis of composite plate girders with different configuration of stiffeners. The results of analytical and numerical investigations indicate that the proposed method can accurately estimate the ultimate shear capacity of composite plate girders. In addition, it is shown that the diagonal stiffeners on one hand can reduce the buckling effects of shear panel of girders and on the other hand can increase the strength of elastic shear buckling and ultimate shear capacity of girders well in comparison with the unstiffened thin steel plate girders.