铝合金桁架桥受施工顺序影响的力学性能研究

摘要

为研究施工顺序对桁架桥的受力影响,对结构安全性进行评估.以某铝合金人行天桥为例,利用MIDAS软件进行施工阶段全过程分析,对比分析施工顺序不同时铝合金桁架桥的结构效应差异,定量分析了铝合金桁架桥的力学性能变化.计算得到了施工顺序改变前后该桁架桥的跨中挠度值、挠度差值和各杆件应力值及其应力差值.结果表明,缺失部分斜腹杆情况下安装主梁,然后桥面附属结构全部安装完成以后再安装缺失腹杆时,桁架桥的跨中竖向挠度最大增加1.46mm,上弦杆应力最大增加11.44MPa,下弦杆应力最大增加8.50MPa,竖腹杆应力最大增加6.53MPa,斜腹杆应力最大增加5.34MPa,约半数以上杆件的应力均发生了变化,结构的杆件不按正常的顺序施工时会降低桁架桥的承载能力.%In order to examine the influence of the construction sequence and evaluate structural safety,fullrange analysis of an aluminum truss bridge was carried out by using MIDAS software.Influence of structural due to construction sequence were studied to find out the changes of its mechanical properties.Mid-span deflection,bars' stress and their differences in value owing to the construction sequence were calculated.The results showed that if the missing diagonal web members are installed after the main girder structure and bridge deck attachment structure,the maximum mid-span vertical deflection would increase 1.46mm,the maximum stress in the top chord would increase 11.44MPa,the maximum stress in the bottom chord would increase 8.50MPa,the maximum stress in the vertical web member would increase 6.53MPa,the maximum stress in the diagonal web member would increase 5.34MPa.And about half of the stress of the rods are changed.The bearing capacity of the truss bridge is reduced when the rods are not installed in the normal order.