跨航道简支钢桁梁桥主桁节点与横梁连接性能研究

Study on Connection Performance Between Main Truss Joint and Beam of Simply Supported Steel Truss Bridge Across Channe

对于简支钢桁梁桥,主桁受力变形会引起桥面系的变形,进而使横梁产生面外弯矩,影响整体受力性能;同时横梁面内也承受较大的弯矩,使得横梁与主桁连接部位应力较大。为改善横梁面外受力与面内受力情况,提高主桁节点与横梁连接性能,首先建立整体模型并通过参数分析研究采用不同施工方法对横梁面外弯矩的影响;然后,基于局部模型分析了横梁与主桁连接部位的受力情况,并对比了不同构造措施对此连接区域受力的改善程度。研究表明:采用纵梁滞后安装、设置长圆孔等措施可以一定程度上降低恒载作用下纵梁与主桁纵向变形不一致导致的横梁面外弯矩,但是考虑活载效应后,各种措施降低效果有所减少;对于传统的横梁与主桁连接形式,由于横梁面内弯矩较大,腹板与主桁连接角钢会出现较大的应力,采用纵梁滞后安装、设置长圆孔等施工措施不能有效降低此应力,故成为结构的薄弱环节;在横梁上翼缘与主桁连接位置采用角钢连接的加强构造形式可以有效提高节点刚度,降低主桁与横梁连接部位的应力水平;采用整体节点的构造形式则可以有效避开横梁与主桁连接的受力薄弱位置,新的连接位置距离主桁一定距离,从而大幅度降低了连接位置的应力水平。

For a simply supported steel truss bridge,the stress deformation of the main truss will cause the deformation of the bridge deck system,and then cause the out of plane bending moment of the beam,which will affect the overall mechanical performance;at the same time,the beam also bears large bending moment,which makes the stress at the connection between the beam and the main truss larger.In order to improve the out of plane and in-plane stress of the beam and improve the connection performance between the main truss node and the beam,firstly,an overall model is established and the influence of different construction methods on the out of plane bending moment of the beam is studied through parameter analysis;then,based on the local model,the stress of the connection between the beam and the main truss is analyzed,and the improvement of the stress in the connection area by different structural measures is compared.The research shows that the out of plane bending moment of the beam caused by the inconsistent longitudinal deformation of the longitudinal beam and the main truss under dead load can be reduced to a certain extent by adopting the measures of lagging installation of the longitudinal beam and setting long circular holes,but the reduction effect of various measures is reduced after considering the live load effect;for the traditional connection form of cross beam and main truss,due to the large bending moment in the plane of cross beam,there will be large stress in the connecting angle steel between web and main truss.The construction measures such as lag installation of longitudinal beam and setting long round hole can not effectively reduce this stress,so it has become a weak link of the structure;the strengthening structure of angle steel connection at the connection between the upper flange of the beam and the main truss can effectively improve the joint stiffness and reduce the stress level at the connection between the main truss and the beam;the structural form of integral joint can effectively avoid the weak stress position of the connection between the beam and the main truss,and the new connection position is a certain distance from the main truss,which greatly reduces the stress level of the connection position.