外立面脚手架施工方案

5+2.63+11.24Р =19.22NР2.活载(作业层施工荷载)的标准值QkР Qk=n laqkР由表5-16查得施工荷载按2 KN/m2 ,两层同时存在,并考虑内挑300偏心部分全部作用于一根立杆qk=2×(1.2/2+0.3)=1.8 KN/mРQk=1.4×1.8×2=5.04 KNР3.风荷载的标准值qwkР qwk=laωkР ф=0.4Р ωk=0.7us uzω0Р离地面5m时 us=1.3ф uz=0.8(B类)Р qwk=1.4×1×0.7×1.3×0.4×0.8×0.35=0.143KN/mР离地面46.8m时 us=1.3ф uz=1.63(B类)Р qwk=1.4×1×0.7×1.3×0.4×1.63×0.35=0.29KN/mР脚手架的整体稳定Р1.计算轴心力设计值N’Р N’=1.2(Gk + Qk)Р验算底部截面时,Р N’=1.2×( 19.22+ 5.04)=29.11 KNР验算46.8m处截面时,Р N’=1.2×( 7.98+ 5.04 )=15.62 KNР计算风荷载弯矩MwР Mw=0.12 qwkh2Р离地面5m时=0.12×0.143×1.8×1.8=0.056KNmР离地面46.8m时=0.12×0.29×1.8×1.8=0.113KNmР确定稳定系数ΨР μ=1.53 则λ=kl0/I=1.155×1.8×1.53/0.0158=201Р查表,得Ψ=0.179Р验算稳定РN’/ΨA+ Mw/W≤fc≤0.205 KN/mm2Р双立杆稳定Р 29.11/(0.179×489×2)+56/5080Р =0.166+0.011Р =0.177KN/mm2≤0.205KN/mm2(合格)Р单杆稳定Р15.62/(0.179×489)+113/5080Р =0.178+0.022Р =0.2≤0.205KN/mm2(合格)。