【摘要】 目的对比研究某斜拉弯桥不同的有限元分析模型,给出该桥合理的有限元分析模型,为该桥的长期监测和安全评估提供基础.方法分别采用板壳单元、即考虑弯曲又考虑剪切变形的梁格单元以及考虑弯曲但不考虑剪切变形的梁格单元处理某斜拉弯桥的钢箱梁.对比分析3种不同有限元分析模型的计算结果,确定出该斜拉弯桥合理的有限元模型.结果桥面钢箱梁分别采用3种有限元分析模型计算时,不同模型给出的下游侧拉索应力值差别较大,上游侧拉索及背索的应力值差别较小.采用即考虑弯曲又考虑剪切变形的梁格单元与采用板壳单元模型时,计算给出的主塔弯矩值以及桥面下游纵向腹板处上顶板和下底板的等效应力值较为接近.结论钢箱梁采用即考虑弯曲又考虑剪切变形的梁格单元与钢箱梁采用板壳单元模型,都可以作为该桥合理的有限元分析模型.当钢箱梁横隔板间距不远大于梁高时,不能忽略梁剪切变形的影响,此时采用考虑弯曲但不考虑剪切变形的梁格单元模拟钢箱梁不合理.更多还原

【Abstract】 The establishment of the reasonable finite element model is studied for a cable-stayed curved bridge in order to provide the basis of long term monitoring and safety evaluation for the bridge.The shell element and beam-gird element are used to simulate steel box girder of the bridge.Two kinds of beam-gird elements are used for the finite element model respectively.One(Timoshenko beam)takes both the bending deflection and shear deflection into consideration.The other(Euler-Bernoulli beam)considers the bending deflection but neglects the shear deflection.The states of stresses are analyzed for the main members of the bridge under the dead weight for the three models of this bridge respectively.The reasonable finite element model for this bridge can be given by comparing the calculation results obtained from the three different finite element models.The corresponding stress values of downstream cable given by the three different models are quite different,but the corresponding upstream cable and back-stays stress values are close to one another.The bending moments of the main tower and the equivalent stresses of the top and bottom wings just at the outer downstream steel web,obtained from the model of Timoshenko beam element,are closer to those of the shell element model rather than the Euler-Bernoulli beam model.The conclusions are that the shell element model and Timoshenko beam element model are the reasonable models for simulating steel box girder of the bridge.The Euler-Bernoulli beam model is unreasonable because the distances between the diaphragms are not so much bigger than the height of the steel box girder that the effect of shear deflection can not be neglected.更多还原