1. 怎么验算屋面压型钢板符合设计的要求
屋面板压型钢板的验算
屋面材料采用压型钢板,檩条间距为0.9M,
设计活荷载0.75KN/M2, 恒载0.2KN/M2, 基本风压2.59 KN/M2,
选用830型PU发泡板,板厚0.426mm, 截面形状及尺寸见:
Wx=4.02Cm3=4020mm3 Ix=7.98Cm4=79800mm4
分析:
(1) 内力计算: 压型钢板采用单波线荷载
qx1=0.75KN/m2 x1mx1.5=1.125KN/m qx2=2.59KN/m2 x1mx1.5=3.885KN/m qx=0.2KN/m2x1m x1.35=0.27KN/m
q=1.125KN/m+3.885KN/m+0.27KN/m=5.28KN/m 按简支梁计算压型钢板跨中最大弯距 Mmax=1/8qL2
=1/8 x 5.28KN/M x( 0.9m)2=0.594KN.M
(2) 截面几何特性
由830型PU发泡板,板厚0.426mm得知: Wx=4.02Cm3=4020mm3 δ=Mmax/Wx
=0.594kN.M/4020mm3
=0.594x103x1x103mm/4020 mm3
=147.76N/mm2<[w]=215N/mm2 满足要求 (3) 强度验算 (a) 正应力验算 δ= Mmax/Wx
=0.594KN.M/79800mm3=74.436N/mm2<[w]=215N/mm2 满足要求 (b) 剪应力验算 Vmax=1/2qL
=1/2 x 5.28KN/m x 0.9m=2.376KN (c) 腹板最大剪应力: δ=V/∑ht
= 2.376KN x 103/( 2 x25mm x 0.5mm) =2.376 x 103 / (2 x 25 x 0.5)
=95.04N/mm2 < [ f ]=120N/mm2 满足要求 (4) 钢度验算
按单跨简支板计算跨中最大挠度 Wmax=5qxL4 / 384EIx
=5 x 0.27KN/N /1.4 x 0.9M x 1012 / (384 x 2.06 x 105 x79800 mm4) =0.13mm < [w] = L/300 = 3.4mm 满足要求 通过以上计算,可知满足设计要求.