施工超载对桥梁结构安全性和耐久性的影响

On Influence of Construction Overload to the Safety & Durability of Bridge Structure

超载对桥梁结构的安全性和耐久性的影响是致命的,应对施工过程中的超载现象引起重视。按公路桥梁设计规范中对荷载的规定,给出了公路-Ι级和公路-ΙΙ级汽车车道集中荷载与跨径的关系式及曲线。为便于计算比较,通过计算弯矩,将集中荷载换算成等代均布荷载,得出了换算公式。列出了跨径为5～50 m的简支梁由集中荷载换算的等代均布荷载数据及曲线。结果显示,对于设有人行道并采用石材铺面的城市桥梁,特别是改造工程,必须验算恒载作用,注意是否出现超载现象;当上部结构采用预制架设时,在设备过孔、梁上运梁等过程中,都有可能导致梁结构的超载,成为控制设计的重要工况。

Overload will result in deadly influence on the safety and durability of bridge structure,so it shall be paid enough attention during the construction period.According to the specified load of roads & bridges design code,the relations and curves between vehicle lane(Class I & Class II of Highway) concentrated loads and spans are given.For easy calculation & comparison,concentrated load is converted into equivalent uniform distributed load and the conversion formula is obtained through calculating bending moment.The equivalent uniform distributed load data(converted from concentrated load) and curves of the simply supported beams with spans from 5 m to 50 m are carried out.The results can show that 1) for urban bridges with pedestrian lane and stone pavement especially for reconstruction projects,the dead load must be checked with paying attention to overload issue;2) when upper structure using prefabricated erection,during process of equipment through holes and transporting beam above beam,the overload of beam structure will appear probably,which will become one of important working conditions of control design.