Q460GJ钢抗弯设计强度和可靠性分析

Bending design strength and reliability analysis of Q460GJ steel

建筑结构用钢板因其优异的综合力学性能,已在多个国内重大工程中得到应用。Q345GJ钢的设计指标已列入相关国家和行业标准,且已有研究基于试验提出Q460GJ钢压弯设计强度,受弯设计强度亟待补充。基于27个Q460GJ钢受弯构件整体稳定承载力试验结果,统计获得其计算模式不确定性统计参数,结合既有研究中Q460GJ钢材料性能不确定性和几何参数不确定性的统计分析结果,获得Q460GJ钢受弯构件抗力不确定性统计参数。采用可靠性方法计算获得不同荷载组合、荷载比和可变荷载比下的抗力分项系数,分析其变化规律并建议抗弯设计强度取435MPa。对建议设计强度进行可靠性校核,结果表明:在建议设计强度指标下,Q460GJ钢受弯构件在绝大多数情况下的可靠指标大于3.2,满足《建筑结构可靠性设计统一标准》(GB 50068—2018)的要求。

Due to its excellent comprehensive mechanical properties,domestic steel plate for building structures have been used in many major building projects in China. The design strength of Q345GJ steel have been provided in relevant national standards and industry codes. Previous studies have proposed the design values of Q460GJ steel under compression-bending based on some experimental results,but the bending design values are not given and need to be further studied. The statistical parameters of the calculation mode uncertainty are obtained based on the test results of the global stability bearing capacity of 27 Q460GJ steel bending members. Based on the statistical results of the Q460GJ steel material properties uncertainty and geometric uncertainty in the previous study,the statistical parameters of resistance uncertainty of bending member welded by Q460GJ steel are obtained. The reliability method is used to calculate the partial factors for resistance under different load combinations,load ratios and variable load ratios. The changing laws of the partial factors for resistance are concluded and the bending design value is recommended to be 435 MPa. Finally,reliability check of the recommended design value is carried out,and the results show that the reliability index corresponding to the recommended design value is greater than 3. 2 in most cases,which meets the requirements of GB 50068—2018 “Uniform standard for reliability design of building structures”.