预应力活性粉末混凝土箱梁抗弯性能试验

为研究预应力活性粉末混凝土(RPC)箱梁的正截面受力性能,进行了2片预应力RPC箱梁的抗弯性能试验,研究了RPC箱梁的受力变形特征以及顶板横向预应力对其抗弯性能的影响。结果表明:预应力RPC箱梁具有良好的变形能力,其极限变形可超过跨径的1/50;RPC箱梁正常使用阶段的裂缝宽度和短期刚度可参照《纤维混凝土结构技术规程》（CECS 38:2004）的相应公式计算,其中的钢纤维影响系数可分别取为0.4和0.2;RPC箱梁顶板内的横向预应力对截面抗弯承载力的影响较小,但会使受压区混凝土的应变分布更加均匀,从而减弱箱梁顶板受压的剪力滞效应并增加构件的延性;试验中对顶板内施加2.95 MPa的横向预压应力（仅为RPC棱柱体抗压强度94 MPa的3.1%）后,可使箱梁受压翼缘的有效分布宽度增加约10%,构件延性指标增加约3%。试验结果验证了提出的预应力RPC箱梁正截面抗裂和抗弯承载力的计算公式。     

短深大板梁承载性能与破坏模式研究

短深大板梁常在钢结构工业厂房中用于支撑重型设备,这类构件跨高比通常在5左右。由于腹板跨高 比较大,其抗剪承载能力对构件的整体承载力性能有很大影响。然而,现有设计方法对剪力比大于0.5的构件 考虑不足。为此,设计完成了4个短深大板梁试件的静力加载试验,并验证了相应的有限元模拟方法。试验及 有限元分析结果表明,大板梁主要有两类破坏模式,分别称做“弹塑性整体失稳破坏”和“腹板局部失稳破 坏”。由于板梁构件具有明显的局部-整体相关性,现有的截面分类设计方法及其遵循的“单一板件准则”针 对其适用性较差。结合钢结构构件设计的发展,将构件分类设计方法拓展到了短深大板梁的范围。建议首先 根据构件的设计参数预测构件的破坏模式,然后采用相应的承载力计算方法进行设计。     

组合梁翼板的有效宽度分析

组合梁混凝土翼板有效宽度取值的合理与否对于组合梁的承载力和挠度分析非常关键。各国规范对其取值相差比较大,且一般都是考虑弹性阶段工作状态时采用,对于目前广泛用于楼盖内力分析中塑性内力重分布的方法,并不适用。为此,作者通过3根正弯矩简支组合梁和一根负弯矩组合梁进行试验,并与已有实验数据相比较,发现有效宽度的取值在弹性阶段和塑性阶段时,各国规范都偏保守,对其合理的取值提出了建议,可供工程设计参考。     

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.     

组合扁梁楼盖水平荷载作用下承载性能分析

为了研究组合扁梁楼盖在水平荷载作用下的承载性能和有效宽度,采用有限元分析软件建立了钢—混凝土组合扁梁整体楼盖三维实体有限元模型,并进行了相应的计算分析.计算结果表明:钢—混凝土组合扁梁楼盖具有较大的水平刚度和较好的空间作用,组合扁梁楼盖在水平荷载情况下有效宽度较竖向荷载作用时小.建议进行组合扁梁整体楼盖试验,进一步研究其有效宽度取值.     

Elastic distortional buckling of continuously restrained I-section beam-columns

Doubly symmetric steel I-section members with thin webs and stocky flanges that have their tension flange restrained fully against translational and lateral rotational buckling deformations and elastically against twist rotation during buckling by the flexibility of a continuous restraint have been shown in previous studies to buckle in a so-called restrained distortional buckling (RDB) mode, involving distortion of the web of the I-section in the plane of its cross-section. These bifurcative buckling modes must necessarily occur in the negative moment region of composite T-beams and in half-through girder bridges. The present paper describes the elastic RDB analysis of a simply supported doubly symmetric I-section beam-column subjected to combined uniform axial force and moment gradient. The study adopts an energy method of analysis. The numerical solutions are used to develop a simple method of predicting the elastic RDB loads of beam-columns for use in design.     

Web openings in horizontally curved composite plate girders

The paper is concerned with the effects of circular or square web openings on the ultimate strength of horizontally curved composite plate girders. Finite element analysis using the computer package LUSAS has been employed to investigate the behavior and ultimate strength capacity of the girders with web openings of different proportions. The opening sizes and their locations within the web panels have been studied in detail, and the results are presented in the form of load–deflection and load–opening size plots. An approximate method to determine the ultimate strength capacity of horizontally curved composite plate girders accounting for the presence of web openings and composite action between the steel girder and concrete slab is presented. The accuracy of the method is established by comparing the predicted strength with the corresponding values predicted by the finite element method.     

Verformungsbezogene mittragende Breite niedriger Verbundträger

Effective width due to deflections of composite girders with shallow height. Due to the high slenderness of composite girders with shallow height their deflection behaviour is of great importance. In many cases the cross sectional dimensions are determined by the limitation of the deflections. In contrary to high composite beams the deflection behaviour of these girders is influenced especially by the bending state and cracking behaviour of the concrete slab. Among others the deflection or the stiffness of the composite girders depend on the effective width of the slab. This article reports on investigations of the deflection behaviour and the effective width of shallow composite girders taking into account the bending state and the cracking of the concrete slab. At first it is shown that for the calculation of stresses a different value of the effective width has to be taken into account than for the calculation of deflections. On basis of extensive experimental, analytical and numerical investigations the influences on the effective width are analysed. A wide‐ranging parametric study leads to the development of an approach of the effective width for the calculation of deflections and a proposal for a quasi‐elastic calculation of the deflections of shallow composite girders. At this it turns out that the effective width due to deflections is influenced above all by the bending state of the concrete slab, its cracking behaviour, its ratio width to length, the ratio of the individual stiffness components of the composite cross section and the load level. On basis of the proposed approach for the calculation of the effective width the deflections of shallow composite girders can be determined realistically. This leads to a more economic design of composite shallow girders than until now.     

Horizontally curved composite plate girders with trapezoidally corrugated webs

This paper is concerned with horizontally curved composite plate girders with trapezoidally corrugated webs. Finite element analysis using the computer package LUSAS is employed to investigate the behaviour and ultimate strength capacity of the girders. The presence of web openings of different proportions and their effects on the behaviour and ultimate strength of the girders are also investigated. Parameters that affect the behaviour of these girders are slenderness of the web d/t, web panel aspect ratio b/d, width to the depth of corrugation ratio b_h/h and size of openings. Influence of these parameters on the collapse behaviour is examined. Results are obtained in terms of ultimate strength, failure mechanism and load-deflection curves from the finite element analyses and, some typical results are presented herein. An approximate method to compute the shear capacity of these girders is presented. Comparison of the results with those predicted using the finite element method established the accuracy of the proposed method.     

Experimental study on shear behavior of box section bamboo-steel composite beams

为研究以冷弯薄壁型钢和竹材人造板通过结构胶复合而成的箱形截面钢-竹组合梁的受剪性能,以梁截面的翼缘及腹板竹胶板厚度、型钢翼缘宽度和剪跨比等为主要参数,对6根钢-竹组合箱形梁进行受剪试验,观察各级荷载作用下组合梁的应变和挠度发展,分析其破坏过程和破坏机理,研究组合梁受剪性能的影响因素,探讨钢-竹组合箱形梁的受剪承载力及变形计算方法。研究结果表明：钢-竹组合箱形梁整体工作性能优良且组合效应显著,其受力过程经历弹性和弹塑性两个阶段,具有良好的延性和安全储备;增加翼缘和腹板处竹胶板厚度可提高组合梁的受剪承载力,减小剪跨比可有效提高组合梁的受剪能力,同时适当减小型钢翼缘宽度能使梁的受剪性能进一步增强;采用所提出的组合梁的跨中挠度计算公式得到的计算值与试验值吻合较好,组合梁受剪承载力的计算公式所得结果偏于保守。     

钢板混凝土组合墙体局部稳定性轴压试验研究

进行了4个应用于核电工程的钢板混凝土组合墙轴压试验,试验设计中主要考虑距厚比参数的不同。分析了构件的破坏机理、荷载-位移曲线、钢板的荷载-屈曲曲线。分析结果表明：钢板的屈曲对试件整体刚度影响不明显,栓钉能有效地保证钢板和混凝土协同工作;随着距厚比变小,试件极限承载力有所提高,钢板的屈曲应变变大。在试验分析基础上,给出了组合墙体的初始刚度和极限承载力的经验公式,导出了适合钢板弹性屈曲应变的理论公式。     

基于不同种类竹板的钢-竹组合梁受弯性能对比分析

冷弯薄壁型钢分别与重组竹、竹胶板通过结构粘结剂复合成工字形组合梁,以竹板厚度、梁截面高度、薄壁型钢壁厚及翼缘宽度为参数,对冷弯薄壁型钢-重组竹组合梁、冷弯薄壁型钢-竹胶板组合梁这两种试件进行弯曲性能试验,围绕组合梁破坏形态、整体性能差异、承载力能力及其影响因素、短期集中荷载作用下变形情况进行比较。结果表明,两种钢-竹组合梁试件整体工作性能均表现良好,组合效应突出,具有较高的承载力及良好的延性;冷弯薄壁型钢-重组竹组合梁破坏形态比较单一,与此相比冷弯薄壁型钢-竹胶板组合梁破坏形态则较为多样;组合梁抗弯承载力与材料力学性能密切相关,同时随着竹板厚度、梁截面高度、薄壁型钢壁厚及翼缘宽度的增加,承载能力有效提高,且在同等情况下冷弯薄壁型钢-竹胶板组合梁提高的幅度明显大于冷弯薄壁型钢-重组竹组合梁;两种组合梁按编号对应相比较,试验参数基本相同的条件下,冷弯薄壁型钢-重组竹组合梁的正常使用极限状态和承载能力极限状态下的承载力均高于冷弯薄壁型钢-竹胶板组合梁,平均提高约35%。     

集中荷载作用下钢-混凝土组合梁界面滑移及变形

报道了8榀集中荷载作用下钢-混凝土组合简支梁的滑移规律和变形的试验结果。利用Goodman弹性夹层假设,推导了钢-混凝土组合简支梁的界面滑移和挠度变形的理论计算公式。该理论公式既能描述组合梁的界面滑移规律,又可以计算界面滑移对组合梁变形挠度的影响。利用通用有限元软件对钢-混凝土组合梁的界面滑移与变形进行了非线性有限元分析,并将多项计算结果进行了比较。通过大量理论计算,探讨工程设计中合适的剪力连接度。本文所得的理论计算公式,将方便工程设计人员对钢-混凝土组合结构滑移和变形挠度进行计算,并为其极限承载力的有限元计算提供了理论基础。     

两边连接薄钢板剪力墙抗侧力性能研究

为了研究两边连接薄钢板剪力墙的抗侧力性能,以钢板高厚比(400、611)和高宽比(0.61、1.10、1.57)为参数,设计6个两边连接薄钢板剪力墙试件,对其进行水平低周反复荷载试验,研究试件的滞回性能、骨架曲线、承载力、耗能能力、刚度退化等性能。试验结果表明,随着钢板高厚比和高宽比的减小,试件的抗侧刚度、承载力和耗能能力明显提高,高宽比对承载力影响较大;各试件屈服时的位移角在1/200~1/160之间,极限位移角均大于1/50,位移延性系数均大于5,具有较好的延性,高宽比和高厚比对屈服位移角的影响较小。利用有限元方法对各试件进行数值分析,分析结果与试验结果吻合较好,随钢板高宽比减小,拉力带的有效宽度增加,承载力和抗侧刚度增大。     

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。     

Influence of group studs layout style on static behavior of steel-concrete composite small box girder models

设计制作4片具有不同栓钉布置方式的钢-混凝土组合小箱梁模型进行试验研究,并进一步采用有限元法,考虑组合梁材料的本构关系和接触问题等,对其从弹性荷载至极限荷载下的受力行为进行分析,得到从开始加载至极限荷载下各模型梁的荷载-挠度曲线、跨中钢梁底板应变随荷载的变化曲线和弹性阶段钢梁与混凝土板相对滑移的分布,以及组合梁的屈服荷载、极限荷载和破坏时混凝土板的应力云图等。与试验测试结果的对比表明,采用群钉布置的快速施工组合梁达到完全抗剪要求时,组合梁承载能力与焊钉数量和布置型式关系不大,按照文中建立的有限元模型能较好地分析预测快速施工不同群钉设计参数下钢-混组合梁的屈服荷载和极限荷载。     

交错桁架结构体系的极限承载力及其影响因素分析

本文基于非线性连续介质力学理论和内力屈服面塑性流动理论,推导出计算交错桁架结构体系极限承载力的二阶弹塑性刚度方程。在该刚度方程的构造中不仅考虑了单元截面上的轴力、剪力、弯矩、扭矩以及结构剪切变形的影响,还考虑了杆端塑性铰处内力之间的相互影响。数值计算表明本文方法具有良好的计算精度。最后,本文还在此基础上就结构高宽比、荷载偏心、柱子截面形式和平面桁架的形式等因素对交错桁架结构极限承载力的影响进行了探讨,结果表明当交错桁架结构体系达到其极限承载力时,杆件的塑性铰主要集中分布在下部楼层,设计时建议适当加大下部楼层的杆件截面,以保证结构具有足够的极限承载力。此外,在偏心荷载作用下,柱子截面形状对结构极限承载力的影响较大,其工形截面的影响要比箱形截面更为显著。     

钢-竹组合工字形柱偏心受压性能试验研究

为研究钢-竹组合构件偏心受压时的受力性能,设计制作了 36根钢-竹组合工字形柱并进行偏心受压试验.以偏心距、长细比、有无螺钉连接为主要参数,分析不同参数对组合柱破坏形态、承载能力、侧向挠度等的影响.依据采用偏心距增大系数的极限平衡法和引入参数影响系数的统一理论法推导了两种偏压承载力理论计算式.结果表明:钢-竹组合柱受力...     

密布预应力束锚具下混凝土局部受压承载力计算方法

针对广大结构工程师在应用规范公式计算密布预应力束锚具下混凝土局部受压承载力时所遇到的问题,利用已有试验数据,经大量试算和归纳,提出了计算密布预应力束锚具下混凝土局部受压承载力的“整体计算法”和“分别计算取和法”。计算分析表明,当仅有两个局压荷载且局压荷载净距与单个局压荷载分布长度之比不大于0.6及三个和三个以上局压荷载的相邻二局压荷载净距与单个局压荷载分布长度之比不大于0.5时,锚具下混凝土中峰值横向拉应力位于局压荷载合力的正下方,局部受压承载力计算应按“整体计算法”考虑。当仅有两个局压荷载且局压荷载净距与单个局压荷载分布长度之比大于0.6时,在两个局压荷载的下方分别出现了峰值横向拉应力,局部受压承载力计算应按“分别计算取和法”考虑。当三个和三个以上局压荷载的相邻二局压荷载的净距与单个局压荷载分布长度之比介于0.5～2.0之间时,在两个边端局压荷载下方出现了明显的横向峰值拉应力,各中部局压荷载下方横向拉应力分布较     

部分预应力混凝土梁正截面疲劳性能及计算方法

本文通过16根出现裂缝的先张法部分预应力混凝土试验梁及3根试验吊车梁的静力和疲劳试验,较系统地研究了此类梁的疲劳性能。文中剖析了在重复荷载作用下裂缝截面处钢筋应力的变化规律以及垂直裂缝的开展与闭合;提出了预应力钢筋应力的计算方法和裂缝的控制条件。