工字钢的选择与校核.docx

分析(1)确定危险截面(1)计算简图(2)绘弯矩图 根据 =也虬< a计算例题5-3某车间欲安装简易吊车，大梁选用工字钢。已知电葫芦白重Fi 6.7kN?起至量 f = 50kN,跨度I = 9.5m.材料的许用应力 Q=140MPa,试诜择工字钢的型号。(6.7 + 50)x10, x9.5W. 2- =.'<7140x10"= 962x10 up =962 cm'(4)诜择工字钢型号36cl字钢(5)讨论W: = 962 cm3(7 = 67.6kg/mT型截面傍饮梁，城面尺寸如图示.b.,=30MPa,匠=60MPa,试校核梁的强度.分析:非对称截面，要导找中竹轴位苫作弯矩图，寻找需要校核的藏面要同时满足bg <h , crCfnax <ac解：CD求藏面形心80x20x10 + 120x20x80 _yr = 52 mm80x20 + 120x20(2)求藏面对中性轴/的惯性矩80x20312+ 80x20x42?20xl203H12+ 20x120x28"|OAVUAVA I 5 I|. M +.加!. + g T2 5kNmbg=27.2MPa<(3) 作穹炬图(4) B截面校核_ 4x10x52x10 g7.64x1 (T=27.2x 1 tfPa=27.2MPa<q_4xltfx88xlQ-5Zg 7.64x1 甘=46.1xl(Pa=46.1MPa<(7 QO(梁满足强匝要求6c(气皿=46呷IPav匠匕 (5) C裁面要不要彼核_ 2.5x103x88x1Q3:7.64x10=28.* "Pa = 28.8MPa<crJ