超大直径筒仓仓顶现浇混凝土施工悬吊支撑桁架安全分析

以旋转盘口式扣件钢管桁架支撑体系为研究对象,针对筒仓施工中支撑平台可能出现的局部拉索或杆件失效,利用ANSYS软件建立剩余结构有限元模型并进行数值分析。考虑两种最不利施工工况:局部拉索失效,分析局部受力杆件失效时结构的承载能力。分析结果表明:当第一圈拉力最大的悬吊钢绞线失效后,其余钢绞线通过应力重分布,使桁架竖向位移略有增加,钢绞线应力增大,但仍能提供桁架承担施工荷载;当桁架下弦杆中应力最大的杆件失效、桁架上弦杆和斜杆失效后,对结构影响都较小,不影响结构承担施工荷载,支撑体系具有较高的安全性。

THE SAFETY ANALYSIS OF SUSPENSION SUPPORT TRUSS ON TOP OF LARGE-DIAMETER SILO UNDER CONCRETE CONSTRUCTION

The steel-tube truss supporting system made of rotating-fastening members was studied,a FE model of the remaining structural model was established by ANSYS software to do experimental research and analyze local cable failure or member failure of the support platform during silo construction,which would occur. Two of the most unfavorable conditions of construction were considered,one was the bearing capacity of the structure when local cable failed,the other was local stressed member failure. The results showed that when failure occurred in the first lap suspension strand with maximum tension,the rest of the strand through the stress redistribution,truss vertical displacement increased slightly,strand stress increased,which could still provide truss to undertake construction load. There would be less impact after the members with largest stresses of the bottom chord,as well as the upper chord and the diagonals of the truss failed,which could not influence the ability of the structure to bear construction loads,hence the support system has a higher security.