.75mmР满足要求Р四、次梁验算Р当可变荷载Q1k为均布荷载时:Р计算简图:Р(图10)?可变荷载控制的受力简图1Р由可变荷载控制的组合:Рq1=0.9×{1.2[G1k+(G2k+G3k)h]a+1.4Q1ka}=0.9×(1.2×(0.3+(24+1.1)×120/1000)×300/1000+1.4×2.5×300/1000)=2.018kN/mР由永久荷载控制的组合:Рq2=0.9×{1.35[G1k+(G2k+G3k)h]a+1.4×0.7Q1ka}=0.9×(1.35×(0.3+(24+1.1)×120/1000)×300/1000+1.4×0.7×2.5×300/1000)=1.869kN/mР取最不利组合得:Рq=max[q1,q2]=max(2.018,1.869)=2.018kN/mР当可变荷载Q1k为集中荷载时:Р由可变荷载控制的组合:Рq3=0.9×{1.2[G1k+(G2k+G3k)h]a}=0.9×(1.2×(0.3+(24+1.1)×120/1000)×300/1000)=1.073kN/mРp1=0.9×1.4Q2k=0.9×1.4×2.5=3.15kNР(图11)?可变荷载控制的受力简图2Р由永久荷载控制的组合:Рq4=0.9×{1.35[G1k+(G2k+G3k)h]a}=0.9×(1.35×(0.3+(24+1.1)×120/1000)×300/1000)=1.207kN/mРp2=0.9×1.4×0.7Q2k=0.9×1.4×0.7×2.5=2.205kNР(图12)?永久荷载控制的受力简图Р1、强度验算Р(图13)?次梁弯矩图РMmax=0.651kN·mРσ=Mmax/W=0.651×106/(64×103)=10.179N/mm2≤[f]=11N/mm2Р满足要求Р2、抗剪验算Р(图14)?次梁剪力图РVmax=3.365kN
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