S350冷轧薄板冷弯超薄壁型钢构件设计可靠度分析

Design Reliability Analysis of Cold-Formed Thin-Walled Steel Members with S350 Hard-Rolled Steel Sheets

基于国内厚度不大于2mm的S350冷轧薄钢板材性数据、冷弯薄壁型钢构件几何尺寸数据及已完成的轴压、偏压、受弯构件承载力试验数据,对厚度不大于2mm的S350超薄壁冷弯型钢构件的材料强度不定性、几何特性不定性、计算模式不定性进行了分析。采用JC法,按现有规范的抗力分项系数计算了各类基本构件在不同可能荷载组合下的可靠指标,并根据可靠度分析结果,提出了对现有规范承载力计算值的建议修正方法。结果表明:对于厚度不大于2mm的S350超薄壁冷弯型钢构件,当翼缘宽厚比满足规范要求时,按现有规范的抗力分项系数计算得到的轴压构件可以满足目标可靠度的要求,偏压构件的可靠指标低于目标可靠指标,受弯构件的可靠指标略低于目标可靠度。按建议方法计算偏压构件的承载力时,偏压构件的可靠指标大于目标可靠指标。最后给出了厚度不大于2mm的S350超薄壁冷弯型钢构件的强度设计指标建议值。

Based on the data including the yield strength,the dimensions of sections and the load-carrying capacity of existing experiments on axially-compressed members,eccentrically-compressed members and bending members,the uncertainty of material strength,geometric characteristics and calculation mode of S350 cold-formed thin-walled steel with thickness no more than 2 mm was analyzed.Then,the JC method was used to check the required reliability index of S350 cold-formed thin-walled steel sections with thickness no more than 2 mm using the resistance partial factor in current codes under different load combinations.In addition,a modified method of the calculated values of the load-carrying capacity was recommended based on the result of design reliability analysis.The results show that,using the recommended resistance partial factor in current codes,the reliability indexes of the axially-compressed members and the bending members with width-thickness ratio within the limitation of current codes can well meet or are close to the target reliability index,but the eccentrically-compressed members fail to reach the target reliability index.However,the reliability indexes of the eccentrically-compressed members were higher than the target reliability index when the modified method was used.Finally,the recommended design strength value of S350 hard-rolled steel members with thickness no more than 2 mm was proposed for structural design.