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Unfavorable geometric imperfections in steel plate girders subjected to localized loads
Thin-Walled Structures ( IF 6.4 ) Pub Date : 2021-01-12 , DOI: 10.1016/j.tws.2020.107412
S. Kovacevic , N. Markovic , D. Sumarac , R. Salatic

Recent experimental studies have shown that the current EN1993-1-5 patch loading resistance model underestimates the ultimate strength of steel plate girders in certain cases, especially for longitudinally stiffened steel plate girders and longer patch load lengths. In addition to this resistance model, the design standard allows the use of finite element analysis for the ultimate limit state. The existing design recommendations for an adequate ultimate limit state design are found insufficient. In the current paper, the imperfection sensitivity analysis of steel plate girders subjected to patch loading is performed. The paper presents a nonlinear finite element parametric study designed to determine the influence of a variety of geometric imperfections on the patch load resistance of longitudinally unstiffened and stiffened steel plate girders. Experimentally measured, buckling mode-affine, and hand-defined sinusoidal geometric imperfections were varied in the study in combination with varying patch load lengths and relative stiffnesses of the longitudinal stiffener.

The ultimate strength of longitudinally unstiffened and stiffened steel plate girders increases as the patch load length is increased for all the geometric imperfections considered. For relatively small patch load lengths, the relative stiffness of the longitudinal stiffener has no significant influence on the ultimate load regardless of the geometric imperfection. For longer patch load lengths, the ultimate strength is highly dependent on geometric imperfections. The influence of the web panel aspect ratio is shown to be negligible for smaller patch load lengths regardless of the geometric imperfection, while for longer applied loads, the impact of this ratio is dependent on the geometric imperfection.

Unfavorable geometric imperfections in steel plate girders subjected to patch loading are governed by the patch load length and the relative stiffness of the longitudinal stiffener. Different unfavorable geometric imperfections were found for different patch load lengths and relative stiffnesses. Local geometric imperfections defined in the upper web sub-panel yield lower ultimate strengths than global geometric imperfections (defined over the whole web depth). The lowest patch load resistances were returned for geometric imperfections that resembled the deformation at collapse (collapse-affine geometric imperfections). Although the concept of collapse-affine geometric imperfections seems impractical for design purposes (a geometrically and materially nonlinear analysis must be conducted before collapse-affine geometric imperfection shapes are determined), the use of these imperfection shapes is recommended.



中文翻译:

承受局部载荷的钢板大梁中不利的几何缺陷

最近的实验研究表明,当前的EN1993-1-5补片加载阻力模型在某些情况下低估了钢板梁的极限强度,尤其是对于纵向加劲的钢板梁和较长的补片加载长度。除了此阻力模型外,设计标准还允许对最终极限状态使用有限元分析。发现适当的极限极限状态设计的现有设计建议不足。在当前的论文中,进行了受贴片荷载作用的钢板梁的缺陷敏感性分析。本文提出了一个非线性有限元参数研究,旨在确定各种几何缺陷对纵向未加劲和加劲的钢板梁的贴片承载力的影响。

对于所有考虑的几何缺陷,随着补片载荷长度的增加,纵向未加筋和加筋的钢板梁的极限强度会增加。对于相对较小的补片载荷长度,无论几何缺陷如何,纵向加劲肋的相对刚度都不会对最终载荷产生重大影响。对于更长的贴片负载长度,极限强度在很大程度上取决于几何缺陷。对于较小的补丁加载长度,无论几何缺陷如何,腹板纵横比的影响都可以忽略不计,而对于较长的施加负载,该比例的影响取决于几何缺陷。

承受补强载荷的钢板大梁中不利的几何缺陷取决于补强载荷的长度和纵向加劲肋的相对刚度。对于不同的贴片载荷长度和相对刚度,发现了不同的不利几何缺陷。在上部腹板子面板中定义的局部几何缺陷产生的极限强度低于整体几何缺陷(在整个腹板深度上定义)的极限强度。对于类似于塌陷变形的几何缺陷(塌陷仿射几何缺陷),返回了最低的贴片载荷阻力。

更新日期:2021-01-12
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