建筑工程技术-力学试题3.图示简支梁为矩形截面,许用应力〔a〕=10Mpa,试校核梁的强度

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  • 最大应力在梁中间处,最大弯矩:

    Mmax =q(L^2)/8 = (4kN/m)x(6m^2)/8 = 18kNm

    对z轴抗弯截面模量:

    Wz = b(h^2)/6 =(0.2m)x(0.3m^2)/6 =0.003m^3

    最大拉应力:

    σmax = Mmax/Wz = 18kNm/0.003m^3 = 6000kPa =6MPa < 10MPa

    答:梁的抗弯强度足够.