U型加劲肋加固的高强钢面板体系的面内极限抗压强度

通过非线性有限元分析(FEA)研究使用U型加固件纵向加劲的面板的极限抗压强度。对112个由各种细长参数的面板和柱以及加固件组成的模型进行分析。模型包括了普通钢材和高强钢的弹塑性应变硬化本构关系。有限元分析中也包括了初始几何缺陷和残余应力。将有限元分析得出的结果与欧洲规范3EN1993-1-5、FHWA-TS-80–205和其他可用公式计算出的强度进行比较。基于分析结果,可得出一个针对使用普通钢材或高强钢(HPS)加劲板系统的新的强度预测公式。结果表明:当柱的长细比较大时,使用欧盟规范3EN1993-1-5和FHWA-TS-80–205可能导致设计过于保守;而采用所提出简化形式的公式可更精确地预测强度,从而得出更经济的设计。     

Stiffened steel plates under uniaxial compression

The stability of steel plates stiffened with tee-shape sections under uniaxial compression and combined uniaxial compression and bending was investigated using a finite element model. The emphasis of the work presented in this paper was to find the parameters that uniquely describe the strength and behaviour of stiffened steel plates. A finite element model, validated using the results of tests on full-size stiffened plate panels, was used to investigate the scale effect for five dimensionless parameters. The parameters investigated were: the transverse slenderness of the plate, the slenderness of the web and flange of the stiffener, the ratio of torsional slenderness of the stiffener to the transverse slenderness of the plate, and the stiffener-to-plate area ratio. Average magnitude residual stresses and initial imperfections were assumed for this study.A parametric study covering a wide range of dimensionless parameters indicated that stiffened steel plates do not fail by stiffener tripping unless a bending moment is applied to create flexural compressive stresses in the stiffener. Although plate buckling and overall buckling were found to lead to a very stable post-buckling behaviour, the interaction between these two buckling modes was found to give rise to a sudden loss of capacity following initial plate buckling. The plate transverse slenderness, the stiffener slenderness-to-plate slenderness ratio, and the stiffener-to-plate area ratio were found to have a significant effect on this behaviour.A comparison of the numerical analysis results with API and DnV design guidelines indicates that the guidelines predict stiffened steel plate capacity with various degrees of success, depending on the governing mode of failure. Neither guidelines address the potential interaction-buckling phenomenon.     

Experimental studies on stiffened plates under in-plane load and lateral pressure

An experimental study on stiffened plates subjected to combined action of in-plane load and lateral pressure is described in the paper. Details of the experiments and finite element analyses of the specimens tested are presented along with the results. Measurements of initial imperfection in the specimens have been made and included in the analyses. Results show that lateral load carrying capacity of stiffened plate drops with increase in axial load and vice-versa. It is found that plate slenderness ratio has significant influence on the ultimate load capacity of stiffened plates subjected to both in-plane load and lateral pressure. Increase of plate slenderness ratio results in a decrease of ultimate load capacity of stiffened plate. The accuracy of the finite element modelling is established by comparing the results with the corresponding experimental values.     

混合钢U肋加劲板受压整体稳定承载力数值模拟与计算方法

建立受压混合钢U肋加劲板梁单元有限元模型并进行整体稳定分析,通过在梁单元模型中施加等效应力模拟U肋和被加劲板的不同强度,以5种不同强度组合的U肋加劲板试验试件的破坏模式和荷载-位移曲线对数值模拟方法进行验证。采用经试验验证的有限元模型,变化U肋高度、U肋与被加劲板强度与厚度、构件长度,得到混合钢U肋加劲板整体稳定系数,并与各国规范的柱曲线进行比较。结果表明:在压力荷载作用下,由于非等强钢U肋加劲板中钢材强度较低部分较早达到屈服,这将使得构件整体偏心受压,从而导致构件整体稳定系数均小于1; 等强钢M345-U345柱子曲线位于JTG D64—2015中的a,b类柱子曲线之间,并随着相对长细比的增大逐渐向b类柱子曲线靠近; 非等强钢柱子曲线在相对长细比较小时均低于等强钢M345-U345柱子曲线,而在相对长细比较大时的走势基本一致,其中M345-U420和M420-U345两条柱子曲线与JTG D64—2015中的b类柱子曲线接近; M345-U390和M390-U345两种柱子曲线随着相对长细比的增大逐步与等强钢M345-U345柱子曲线重合接近。     

在应力梯度下边缘加劲板的试验和设计

薄钢板结构有3种典型类型:非加劲(无边缘加劲板),加劲(有充足边缘的加劲板)和部分加劲(有部分边缘加劲板)。当被用于冷弯薄壁型钢时,在承受均匀压力和应力梯度下,钢板可能发生弹性屈曲,有6种可能的荷载组合条件。除了应力梯度作用下的部分加劲构件,对所有类型的钢板都进行了试验研究并提出了设计公式。阐述了当部分加劲板的加劲单元尺寸从零到足够产生加劲作用时,在应力梯度作用下部分加劲板的试验情况。研究了单一加劲和复合加劲的边缘加劲类型。利用有效宽度概念,提出了部分加劲构件在应力梯度作用下的设计公式。在此基础上提出了适用于所有构件在任意荷载条件下的有效宽度公式。     

Empirical formulations for estimation of ultimate strength of continuous stiffened aluminium plates under combined in-plane compression and lateral pressure

The present research was undertaken based on the results obtained by the same authors in a sensitivity study on the buckling and ultimate strength of continuous stiffened aluminium plates. Empirical expressions are developed for predicting ultimate compressive strength of welded stiffened aluminium plates used in marine applications under combined in-plane axial compression and different levels of lateral pressure. Existing data of the ultimate compressive strength for stiffened aluminium plates numerically obtained by the authors through the previously performed sensitivity analysis are used for deriving formulations that are expressed as functions of two parameters, namely the plate slenderness ratio and the column (stiffener) slenderness ratio. Regression analysis is used in order to derive the empirical formulations. The formulae implicitly include effects of the weld on initial imperfections, and the heat-affected zone.     

Numerical investigations on dynamic performance of stiffened box steel bridge piers

The aim of this paper is to carry out extensive numerical investigations about the effect of various structural parameters on the dynamic performance of stiffened box steel bridge pier under a strong earthquake ground motion. The considered structural parameters are the local slenderness ratios of stiffener and stiffened wall as well as the global slenderness ratio of the pier. In the present study, all investigated piers are made of high tensile steel with high yield ratio. The non-linear time history analyses are carried out using in-house Finite Element Program DYNAPSS, recently developed by the first author. This program is verified by comparing its results with the results obtained by the general FE program. In this program, the geometrical nonlinearity is considered on the bases of Total Lagrangian formulation, while the non-linearity of structural steel material is considered through implementation of modified multisurface cyclic plasticity model by which real characteristics of high tensile steel material such as, Plateau, Massing type of Bauschinger??s effect, disappearing of Plateau and cyclic strain hardening, are accurately modeled. The results are closely examined in respect with the damage index criterion. From this study, it is found that the increase in slenderness ratios of stiffener does not only increase the damage index, but also may lead to the full collapse. Furthermore, the damage index increases with the increase of local slenderness ratio of stiffened wall and the global slenderness ratio. Also, it is found that when the loacal buckling is not the dominant eigen mode and the pier behave as a single degree of freedom, the natural period has destructive effects when it is close to predominant period of the earthquake. Finally, contour plots of damage index values are presented. These contour plots may be greatly useful for the design of stiffened box steel bridge piers, where, critical values of structural parameters corresponding to certain value of damage index could be determined.     

Ultimate shear strength of intact and cracked stiffened panels

The present paper focuses on the ultimate shear strength analysis of intact and cracked stiffened panels. Several potential parameters influencing the ultimate shear strength of intact panels are discussed, including the patterns and amplitudes of initial deflection, the slenderness and aspect ratios of the plates, and the boundary conditions defined by the torsional stiffness of support members. An empirical formula for the ultimate shear strength of intact stiffened panels is proposed based on parametric nonlinear finite element analyses in ANSYS. Furthermore, the ultimate shear strength characteristics of cracked stiffened panels are investigated in LS-DYNA with the implicit method. Three types of cracks are considered, namely vertical crack, horizontal crack and angular crack. A simplified method is put forward to calculate the equivalent crack length. And the formula for the ultimate shear strength of cracked stiffened panels is derived on the basis of the formula for intact stiffened panels.     

Longitudinally stiffened hybrid steel plate girders subjected to patch loading

Hybrid girders subjected to patch loading have been analyzed in a detailed fashion for the case in which the plates that assemble the girders are transversally stiffened. Scant work, however, is available for the case in which the girders are hybrid and, simultaneously, longitudinally stiffened. The driving force for developing the present research work is to complete the knowledge of the patch loading field for the particular structural alternative of a hybrid steel plate girder assembled with a longitudinal stiffener. In the current paper, a numerical database of 255 simulations on longitudinally stiffened steel girders subjected to patch loading developed by the authors is presented. The results obtained are used for assessing the resistance of longitudinally stiffened hybrid steel plate girders subjected to patch loading. Some discrepancies between the numerical and EN1993-1-5 results are pinpointed. A design proposal which enhances the current EN1993-1-5 formulation is given at the end of the paper.     

Empirical formulations for predicting the ultimate compressive strength of welded aluminum stiffened panels

The present study was undertaken by the support from Ship Structure Committee (http://www.shipstructure.org), a North American-based interagency research and development committee, in association with SR-1446 project, and also from Alcan Marine, France. Empirical expressions are developed for predicting the ultimate compressive strength of welded aluminum stiffened panels used for marine applications. Existing data of the ultimate compressive strength for aluminum stiffened panels experimentally and numerically obtained by the SR-1446 project is used for deriving the formulations which are expressed as functions of two parameters, namely the plate slenderness ratio and the column (stiffener) slenderness ratio. The formulae implicitly include the effects of weld induced initial imperfections, and softening in the heat affected zone.     

Influence of corrosion on the ultimate compressive strength of steel plates and stiffened panels

This study concentrates on a comparison between steel plate and stiffened panels subject to localised corrosion. A finite element analysis is used to investigate the effect of random corrosion on the compressive strength capacity of marine structural units. Variables include the extent of corrosion; slenderness ratio and aspect ratio. A corrosion prediction model is incorporated to determine the thickness reduction with time. Corrosion-induced volume loss results in a greater reduction of ultimate strength for slender plates compared to stiffened panels, up to 45%, showing the structural element selection can strongly influence the accuracy of the estimated corrosion damage effect.     

带肋圆管截面钢桥墩的延性影响因素研究

为研究带肋圆管截面钢桥墩在水平反复荷载作用下的延性影响因素,首先通过与试验结果对比,确认有限元分析方法的有效性,然后对承受水平反复荷载作用下的圆管钢桥墩进行一系列参数研究,详细讨论钢桥墩径厚比、纵向加劲肋数量以及纵向加劲肋长细比等对钢桥墩极限承载力和延性性能的影响。研究结果表明,随着钢桥墩径厚比和纵向加劲肋长细比的减小,圆管钢桥墩的延性性能得到很大改善。与配置4根纵向加劲肋相比,配置6根肋后的延性提高效果并不明显,而配置8根肋可以显著提高钢桥墩的延性性能。     

钢板剪力墙低周反复荷载试验研究

本文进行了6个13比例钢板剪力墙的低周反复荷载试验,重点研究了钢板墙极限承载力和滞回性能,为钢板墙结构利用屈曲后强度及抗震设计提供试验依据;本试验揭示了边柱局部屈曲、加劲肋布置形式、加劲板刚度和板高厚比对钢板墙滞回性能的影响。试验结果表明,边柱不出现局部屈曲是钢板墙发挥极限承载力的重要保证;厚板和较强的加劲肋对提高钢板墙滞回曲线的饱满度和滞回环面积是有利的;三种钢板墙以交叉加劲板的承载力和滞回性能最佳,十字加劲板次之,钢板墙结构耗能能力依赖于钢板与边柱的弹塑性变形和钢板面外鼓曲变形。试验曲线与应用弹塑性大挠度有限元法计算的滞回曲线吻合良好;利用屈曲后强度的钢板墙受剪承载力,其试验值与本课题建议公式及有限元值计算结果基本一致。     

Experiments of edge-stiffened plates in uniform compression

There is a large body of literature on the experimental behaviour of steel plates under a variety of loading and edge support conditions. Typically the longitudinal plates edges were either laterally restrained (stiffened) or laterally unrestrained (unstiffened). There are no such plate experiments reported in the literature of plates with a longitudinal edge stiffened with an edge-stiffener (partially stiffened). This paper presents 30 plate tests of plates simply supported on three sides, with the remaining (longitudinal) edge stiffened with an edge-stiffener. The edge-stiffener was increased in size from zero (unstiffened plate) to a size sufficient to create a stiffened edge (stiffened plate). Edge-stiffeners of an intermediate size resulted in partially stiffened plates. The behaviour of partially stiffened plates is fully documented with the aid of a 3D photogrammetry system, and the adequate size of edge-stiffeners required in order to create a stiffened plate edge are discussed. Edge-stiffener types investigated are simple lips, simple inclined lips and complex lips. Design procedures for partially stiffened elements previously inferred from numerical studies are shown to accurately and reliably determine the plate strengths, and further validate the procedure for use as a general strength approach in current international cold-formed steel specifications.     

不同加载角度下T形带肋和多室钢管混凝土构件受弯性能研究

为研究不同加载角度下T形带肋和多室钢管混凝土构件的纯弯性能,以加载角度(0°、63°、90°、117°和180°)为试验参数,进行了 11个T形钢管混凝土构件(包括5个带肋、5个多室和1个无肋)的纯弯试验,获得了破坏形态、弯矩-挠度曲线、应变、受弯承载力和抗弯刚度.建立了不同加载角度下T形构件有限元模型,考虑了残余应力...     

全加劲两侧开缝钢板剪力墙弹性屈曲研究

采用有限元方法对全加劲两侧开缝钢板剪力墙在面内水平荷载作用下的弹性屈曲临界荷载、屈曲模态进行了研究。对影响其弹性屈曲性能的参数进行了分析,包括两侧和中部加劲肋与墙板的刚度比、两侧和中部加劲肋宽厚比以及墙板高厚比和边长比。给出了全加劲两侧开缝钢板剪力墙加劲肋的弹性屈曲设计参考公式,为开缝钢板剪力墙的应用提供依据。     

Behavior of beam web panel under opposite patch loading

Elastic buckling is studied for a panel with various boundary conditions including simple supports, fixed supports and elastic restraints. The panel is subjected to opposite patch loading. Following a review of existing work on the effects of localized compression, also known as patch loading, a study is conducted to take into account the restraints provided by the flanges of the I beam in a realistic manner. This study is based on a finite element model implemented in the CAST3M software. A new equation is proposed to calculate the buckling critical coefficient for a beam web panel considering the rotational stiffness provided by the flanges. The model is then applied to longitudinally stiffened web panels which are subjected to opposite patch loading.A parametric analysis is performed to determine the transition from a global buckling mode to a local buckling mode where the sub-panels on each side of the stiffener behave separately. The numerical results show that the flexural rigidity of the stiffener is the appropriate parameter that governs the buckling mode. From these results, a formula is proposed to calculate the buckling critical coefficient of stiffened web panels.     

锈蚀箱梁极限强度试验中板变形量的分析

根据垂直弯曲荷载下3个锈蚀箱梁板的压应力试验结果,分析初始和倒塌后的板变形量。研究初始缺陷和腐蚀对倒塌后最终变形的影响,得出不同的荷载响应、初始缺陷和板高厚比之间的关系。分析初始缺陷、板高厚比和倒塌后最终变形,建立高厚比准则以计算倒塌后变形。     

Analysis of plate deflections during ultimate strength experiments of corroded box girders

The objective of this work is to analyze the initial and post-collapse plate deflections based on measurement records of the experiments of three corroded box girders subjected to pure vertical bending loading inducing a compressive stress on deck. The effect of initial imperfections and corrosion degradation on the final post-collapse deformation shape has been investigated and a relationship between different loading responses, shape of initial imperfections and plate slenderness has been derived. Analyzing initial imperfections, plate slenderness and final post-collapse deformations, a slenderness criterion has been established to predict the post-collapse deformation shape.     

圆钢管空间滞回试验及材料本构模型

在多种方案对比的基础上,设计圆钢管空间滞回试验,该试验中的加载装置适用于空间三向加载;试验考虑了构件不同长细比、不同空间加载方案的情况,据此设计加载、监测及数据采集系统;通过试验得到不同长细比、不同加载方案下的圆钢管荷载位移滞回曲线,考察这些试验数据随参数变化的规律;编制基于通用有限元软件ABAQUS的用户材料子程序,对试验进行数值模拟,确定各圆钢管试件材料本构方程中的参数,并通过最小二乘拟合方法,获得圆钢管考虑损伤累积的本构方程。通过所编制的接口程序进行理论与试验对比分析表明,数值计算曲线与试验曲线吻合良好,证明该本构方程是准确的,所编制的程序也可用于深入的理论研究工作。