温度效应下的板桁结合钢桥局部分析

板桁结合结构钢桥在日照作用下,因桥面板和主桁升温速度不同而存在较大的温差,这种温差的存在对桥面板与桁架连接部位以及横梁与桁架连接的部位造成不利的影响。以重庆市东水门长江大桥为工程实例,运用有限元分析软件Midas FEA对实桥建立三个节段有限元模型,采用板单元,温度荷载加为单元温度,对局部温差作用进行了分析。结果表明:桥面板应力主要影响位置在横梁的两侧0.3 m内,其应力符号相反;温差19℃时,引起板应力最大2.9 MPa,横梁剪应力在22.8 MPa波动;温差30℃时,应力5.35 MPa,剪应力高达32.52 MPa。根据结构钢材考虑的温差,可知本工程设计的结构在目前考虑的温差效应是安全的,在施工拼装的过程中,应严格控制局部温差。

Analysis of local plate-truss composite of steel bridge based on the temperature effect

When plate-truss composite structural steel bridge is exposed to much sunshine , there will be a big temperature difference between the deck and the main truss , which poses great risks to the joints between bridge deck and plate girder , as well as the joints between bridge beam and truss .The study , takes East Gate Yangtze River of Chongqing as a project example , builds a three-segment finite model of the real bridge by u-sing finite analysis software Midas FEA .We use plate unit and temperature load to make a localized analysis of the temperature difference .The results show that 1 ） the main affecting position by the reactive stress of the bridge plate is within the sides of 0.3 meters, and the force is opposite; 2） the maximum plate stress is 2.9 MPa at the temperature difference of 19℃, and beam shear stress is about 22.8 MPa;and the maximum plate stress is 5.35 MPa at the temperature difference of 30 ℃ and beam shear stress is as high as 32.52 MPa.Based on the structural steel temperature difference , this project design proves to be safe in view of the present temperature difference and it is proposed that in construction assembling process , the local tem-perature should be strictly controlled .