小半径曲线刚构-连续梁桥单箱双室主梁合理构造设计研究

Study of Rational Structural Design for Double-Cell Single Box Main Girder of Curved Rigid Frame-Continuous Girder Bridge with Sharp Radius

为了解小半径曲线刚构-连续单箱双室箱梁桥弯扭耦合作用效应,指导主梁合理构造设计,以莫桑比克某跨海大桥北引桥(小半径多跨曲线刚构-连续单箱双室箱梁桥)为研究对象,采用MIDAS Civil软件建立该桥整体模型,采用ANSYS软件建立局部实体模型,计算不同顶板厚度箱梁的扭转受力性能,分析弯扭作用下箱梁断面各部位剪力分布规律。结果表明:箱梁约束扭转产生的翘曲正应力相对弯曲正应力较小,设计时可忽略不计;顶板整体加厚可降低顶板扭转剪应力和翘曲正应力,可分别降低24%、33%;扭矩对两侧边腹板剪力存在差异影响,对内侧边腹板影响较大,不利影响达40%,弯桥设计时腹板厚度应按受力最不利的内侧腹板控制。

To examine the bending-torsion coupling effect of the curved rigid frame-continuous girder bridge that has sharp radius and has the main girder formed of the double-cell single box beams and guide the rational structural design of the main girder,the north approach of a seacrossing bridge in Mozambique was cited as an example.The bridge is a curved multi-span rigid frame-continuous girder bridge with sharp radius and with double-cell single box beams.The MIDAS Civil software was used to establish the overall model of the bridge and the ANSYS software was used to establish the local solid model of the bridge,to calculate the torsion resistant ability of the box beams with top plate of various thickness and analyze the shear force distribution law in different parts of the box beam section under the action of bending and torsion.The results show that the warping normal stress induced by the torsion resistant force of the box girder is relatively smaller than the bending normal stress,which can be omitted in the design.Increasing the thickness of the overall top plate can reduce the torsional shear stress and the warping normal stress by24% and 33%,respectively.The torsional moment has differential influences on the shear forces in the edge webs on the two sides,and has big influence on the inner edge webs,with an adverse impact reaching up to 40%.Hence,the inner webs with the most unfavorable load bearing condition should be the governing factor in the design of the thickness of the webs of the curved bridge.