0-7)=2.116×10-3m=2.12mm>L/400=300/400=0.75mm按照横梁间距L=0.3m计算,弯曲应力满足要求,可挠度不满足要求。因此,需将横向方木间距加密到0.2m。截面惯性矩I=1/12×b×h3=1/12×1.22×0.0183=5.929×10-7f=5q×L4/(384E×I)(胶合板弹性模量E值查表得4000)=5×47.6×0.24/(384×4000×103×5.929×10-7)=0.418×10-3m=0.418mm<L/400=200/400=0.5mm能满足要求。(2)方木计算①弯曲应力计算纵向方木间距较横向大,这里只计算纵向方木。纵向单根方木每跨所受的荷载为q=(F腹板、横隔梁②+F4+F5)×0.6=(47.6+6)×0.6=32.16KN/m跨中弯矩:M=1/8×q×L2=1/8×32.16×0.6×0.6=1.4472KN·m截面模量:W=1/6×b×h2=1/6×0.1×0.1×0.1=1.67×10-4m2弯曲应力:σ=M/W=1.4472/1.67×10-4=0.8665×104KN/M=8.665Mpa(查材料数据表可知满足要求)②剪应力计算剪力Q=1/2×q×L=1/2×32.16×0.6=9.648KN中性轴以上截面对中性轴的惯性矩Sm=b×h/2×h/4=10×10/2×10/4=125cm3惯性矩:I=1/12×b×h3=1/12×10×10×10×10=833cm4剪应力:τ=Q×Sm/(Ib)=9.648×103×125×103/(833×104×10)=14.48Mpa(查材料数据表可知满足要求)③挠度计算f=5×q×L4/(384×E×I)(胶合板弹性模量E值查表得8500)=5×32.16×6004/(384×8500×833×104)=0.766mm<L/400=600/400=1.5mm,
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