纵向曲线箱形梁结构底板横向应力分析

Analysis of Transverse Stress in Base Plates of Longitudinally-Curved Box Girder Structure

为了解小半径曲线箱梁结构底板受力特性,以底板纵向微段为分析对象,结合其传力机理,对该类结构底板横向应力的计算方法进行研究。依据径向力学平衡,将底板轴向力转变为径向等效荷载,并参照单室箱梁下翼缘正应力分布形式,推导出箱梁底板横向应力计算公式。以中马友谊大桥19号V型墩为工程背景,分别采用本文方法和有限元法计算了底板横向正应力,结果显示:箱梁底板横向正应力大小与曲率半径、底板刚度、腹板刚度有关;曲线外形引起纵横向应力耦合,受力复杂,该类结构底板横向正应力较大;本文方法相对有限元求解横向应力偏大,但相差较小。

To examine the load bearing behavior of base plate of sharp-radius box girder structure,the longitudinal micro-segment of the base plate was taken as the analytical objective.The calculation method to transverse stresses in the base plates of such structure was studied,taking into account the load transfer mechanism.According to radial equilibrium,the axial force in the base plate was transformed to radial equivalent load,and the calculation formula of transverse stresses in the base plates of box girder was derived,referencing the normal stress distribution pattern of lower flanges of single cell box girder.The V-shaped pier No.19 of the China-Maldives Friendship Bridge was taken as the engineering background.The method proposed in this paper and the finite element method were used to calculate the transverse normal stress in the base plate.The results show that the values of transverse normal stresses in the base plate of box girder are related to the curvature radius,and stiffness of base plate and webs.The curve geometry induces longitudinal and transverse stress coupling,making the load bearing condition complicated,as a result,the transverse normal stress in the base plate of such structure is big.Compared with the finite element method,the transverse stresses gained by the method proposed in this paper are relatively bigger,but the difference is small.