压弯钢板延性系数及面向抗震设计的截面分类研究

Ductility factors of steel plates subjected to non-uniform compression and section classification for seismic design

对简支边界条件的压弯矩形钢板进行了考虑几何和材料非线性、残余应力、初始几何缺陷的非线性分析,得到弯矩-边缘纤维压应变曲线和弯矩-曲率曲线,按照两种曲线上延性系数的定义确定不同通用宽厚比下板件的延性系数,拟合了压弯板延性系数计算式。分析表明,按曲率定义延性小于按边缘纤维压应变定义的延性。另外根据面向抗震设计的钢构件截面分类的方法,利用结构延性需求与截面延性需求的关系和得到的截面延性需求的计算式,区分结构影响系数中是否包含超强系数,对各类截面板件的宽厚比进行分界,并拟合了宽厚比分界与结构影响系数的相关计算式。

Considering geometric and material nonlinearities, residual stress and initial geometric imperfections, simply supported steel plates under bending and compression were analyzed. The bending moment-edge compressive strain curves and moment-curvature curves were obtained. Based on the definitions of ductility factors, the relations between ductility factors and normalized slenderness of plates were obtained from the two kinds of curves and approximate formulas for both ductility factors were proposed. The analysis reveals that the ductility factor determined from the moment-curvature curve is less than that from the moment-strain curves. According to the classification of steel cross-sections for seismic design, the paper tentatively proposed the limiting values of width-to-thickness ratio. The limiting values were obtained by using the relationship between the system ductility and the cross-sectional curvature ductility, and based on whether or not an overstrength factor was included in the structural performance factor. A formula was suggested to relate the limiting values of width-to-thickness ratio to the structural performance factor.