斜拉桥扁平空腹钢箱梁悬拼施工时的截面变形

湛江海湾大桥主桥是一主跨为480m的双塔空间双索面混合梁斜拉桥,钢主梁采用扁平空腹流线型钢箱梁,标准梁段横隔板和纵隔板均为桁架式.在悬臂拼装施工过程中,吊机作用梁段与被吊梁段受力不同,在两段梁的接口处存在较大的变形差异.文中采用混合单元建立被吊梁段与吊机作用梁段的三维有限元模型,分析了悬臂拼装阶段钢箱梁拼接口的相对变形,研究了纵横隔桁架刚度等参数对变形的影响.分析表明,大跨度斜拉桥采用全空腹钢箱是可行的,相对变形的大小取决于箱梁的整体刚度和吊机的横向着力点.

Section Deformation of Flat Hollow Steel Box Girder of Cable-Stayed Bridge During Cantilever Erection

The Zhanjiang Bay bridge with a main span of 480 m is a two-pylon cable-stayed bridge with spatial double-cable planes and hybrid girders. The steel girder of the bridge is flat hollow streamline steel box girder with truss-form diaphragms and internal webs. As the loads on the segment being lifted differ from those on the segment supporting the crane, the two segment splices are of various section deformations during the cantilever erection. In order to reveal the relative deformation of box girder sections during the cantilever erection, the 3D finite element models of the segment being lifted and supporting the crane are established via the mixed element method. The influences of several parameters including the truss stiffness on the deformation are then analyzed. The results indicate that the flat hollow steel box girder with truss-form diaphragms and internal webs is feasible to long-span cablestayed bridges, and that the relative deformation of the box girder is governed by the transverse location of craneacting point and the global stiffness of the steel box girder.