Abstract
Structural stainless steel requires appropriate recognition of its beneficial properties such as material nonlinearity and significant strain hardening. The recently proposed Continuous Strength Method (CSM) exploits those benefits through a strain based approach for both stocky and slender cross-sections, and is shown to yield a higher level of accuracy and consistency, as well as design efficiency, in the capacity predictions of stainless steel cross-sections. Although there have been extensive and comprehensive studies on SHS, RHS, round tubes and H-sections stubs, but research into cold-formed stainless steel equal-leg angle section stubs remains scarce. In this paper, the scope of the CSM is extended to cover the design of cold-formed stainless steel equal-leg angle section stubs. Developed FE models included material nonlinearities as well as initial geometric imperfections. A comprehensive parametric study has been carried out covering a wide range of slenderness with different cross section geometries for the considered angle stubs. Cross-section resistances obtained from the numerical study were used to assess the performance of the current Continuous Strength Method (DSM) guidelines and EC3 when applied for stainless steel equal-leg angle section stubs; obtained comparisons showed considerable conservatism. A modified design method for cold-formed stainless steel equal-leg angle section stubs is proposed herein following CSM techniques, which provides considerably more accurate predictions for the considered cold-formed stubs. Reliability of the proposed design equations is also presented showing a good agreement with both experimentally and numerically obtained results.
Highlights
使用EN 1990 - Annex D[35]的方法进行标准统计分析 以评估本文推荐的CSM设计公式的可靠性。表3给出了分 析中使用的关键参数,其中n是FE结果的总数, kd,n 是数 据数量n的设计值(极限状态)分位系数,b是基于每组数据 的最小二乘拟合的FE结果与本文推荐公式计算结果的平 均比值。 Vδ 是相对于承载力模型的试验和FE模拟的变异 系数, Vr 是包含模型和基本变量不确定性的组合变异系 数,γ M 0 是截面承载力的安全分项系数。根据[36]的建议, 奥氏体不锈钢的材料超强系数为1.3,材料强度的变异系 数为0.06。几何性质的变异系数取推荐值0.05。可以看出, 对于不锈钢冷弯等肢角钢截面,具有CSM设计承载力函数 的安全分项系数 γ M 0 略大于EC3[3]中推荐的奥氏体不锈 [1] SEI/ASCE8-02, Specification for the Design of Cold-Formed Stainless Steel Structural Members [Z], in, American Society of Civil Engineers (ASCE), Reston,2002
the scope of the Continuous Strength Method (CSM) is extended to cover the design of cold-formed stainless steel equal-leg angle section stubs
A comprehensive parametric study has been carried out covering a wide range of slenderness with different cross section geometries
Summary
使用EN 1990 - Annex D[35]的方法进行标准统计分析 以评估本文推荐的CSM设计公式的可靠性。表3给出了分 析中使用的关键参数,其中n是FE结果的总数, kd ,n 是数 据数量n的设计值(极限状态)分位系数,b是基于每组数据 的最小二乘拟合的FE结果与本文推荐公式计算结果的平 均比值。 Vδ 是相对于承载力模型的试验和FE模拟的变异 系数, Vr 是包含模型和基本变量不确定性的组合变异系 数,γ M 0 是截面承载力的安全分项系数。根据[36]的建议, 奥氏体不锈钢的材料超强系数为1.3,材料强度的变异系 数为0.06。几何性质的变异系数取推荐值0.05。可以看出, 对于不锈钢冷弯等肢角钢截面,具有CSM设计承载力函数 的安全分项系数 γ M 0 略大于EC3[3]中推荐的奥氏体不锈 [1] SEI/ASCE8-02, Specification for the Design of Cold-Formed Stainless Steel Structural Members [Z], in, American Society of Civil Engineers (ASCE), Reston,2002. SEI/ASCE-8[1]和AS/NZS4673[2]给出的截面长细比限值 2.不锈钢设计规范的截面承载力设计方法 为 0.673 , 大于该值时必须考虑有效截面 。 欧 洲 规 范 3(EC3)[3]将不锈钢截面分为四个级别,其中4级是细长截 面。中国规范CECS-410[4]虽未对截面分类,但对所有设 计截面必须判断是否全截面有效。有效宽度法中,毛截面 面积减小为有效截面,且需基于有效尺寸重新计算所有几 何特性,以考虑局部屈曲引起的承载力降低。有效截面几 国际主流不锈钢设计规范包括美国规范[1]、澳大利亚 /新西兰规范[2]、欧洲规范[3]和中国规范[4]。欧洲规范经 过多次修订后是国际上最新的不锈钢设计规范。然而,所 有这些设计规范都按照传统的有效宽度法来处理细长截 面的局部屈曲。 最近提出的连续强度法(CSM)不对截面分类且通过 连续设计曲线利用材料应变硬化的有利影响。Gardner和 Nethercot[5,6]首先将该方法应用于不锈钢管截面。Gardner
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