一种考虑剪滞效应的斜支承连续箱梁挠曲扭转分析方法

通过在支承坐标系下考虑约束条件,提出一种适用于斜支承连续箱梁挠曲扭转分析的薄壁箱梁单元。该单元具有10 个自由度,可方便地考虑斜支承连续箱梁的剪滞效应和扭翘变形。选取挠曲剪滞微分方程和约束扭转微分方程的齐次解作为单元位移函数,推导出单元刚度矩阵各元素的具体表达式。从剪滞翘曲应力的轴向平衡条件出发,建立双室箱形断面的剪滞翘曲位移函数,并给出了剪滞翘曲几何特性的一般计算公式。用所编制的电算程序SSCBA 对一个3 跨斜支承双室连续箱梁模型进行计算,计算值与实测值和ANSYS 壳单元结果均吻合较好,证实该箱梁单元是可靠的。计算表明:在跨中偏心荷载作用下,斜支承连续箱梁的剪滞翘曲变形和约束扭转翘曲变形对应力分布具有显著影响。

A METHOD CONSIDERING SHEAR LAG EFFECT FOR FLEXURAL-TORSIONAL ANALYSIS OF SKEWLY SUPPORTED CONTINUOUS BOX GIRDER

An element for thin-walled box beams is proposed for the flexural-torsional analysis of skewly supported continuous box girder considering the constraint condition in the supporting coordinate system.The element has ten degrees of freedom and can conveniently simulate shear lag effect and torsional-warping deformation of skewly supported continuous box girder.The element stiffness matrix is derived by taking the homogeneous solutions of the governing differential equations for flexural shear lag and restraint torsion as the element displacement functions.The shear lag warping displacement function for the twin-cell box section is established through the axial equilibrium condition of the shear lag warping stress.General formulas for the geometrical properties of cross section concerning the shear lag warping are presented.The program SSCBA is developed and used to analyze a skewly supported three-span continuous box girder model with twin-cell cross section.The calculated results are in good agreement with the experimental results and the calculated results from shell element of ANSYS.It is shown that the warping deformations of shear lag and restraint torsion affect remarkably the stress distribution in a skewly supported continuous box girder under eccentric load at the mid-span.