习题01(计算部分).docx

例5-1工字形截面200x320x8x6,求绕强轴、弱轴的屈服弯矩、塑性弯矩和截面两边缘塑性区高度占截面高度1/8时的弹塑性弯矩。已知屈服强度fy=235沁人解：(1)求屈服弯矩7200x3203-194x3043I=91939499mm4x12=2x8x2003+304x63=10672139mm4yWyM1291939499=574622mm316010672039=106721mm3100=574622x235=135036170NmmexM=106721x235=25079435Nmmey(2)求塑性弯矩W=2x200x8x156+!x6x3042=637824mm3px4W=1x(2x8x2002+304x62)=162736mm3py4M=637824x235=149888640NmmpxM=162736x235=38242960Nmmpy或根据表51求其近似值M=yM=1.12x135036170=15124