预应力钢箱梁的非线性分析

为提高预应力钢筋梁的计算精度，对预应力钢箱梁的两个受力阶段作了全过程非线性分析，建立了预应力钢箱梁的非线性分析模型，采用平衡原理和能量原理分别推导出预应力钢箱梁在预加力阶段和荷载阶段的控制微分方程，用上述方程进行理论计算所获得的数据，如钢梁的跨国挠度、底板应变均与预应力钢箱梁模型的实验结果符合良好，表明了建立的模型和所推导的控制微分方程的有效性和正确性，对影响钢箱梁刚度的因素诸如预加力的大小，预应力钢索的跨中垂度等进行了详细讨论，讨论结果表明，当外荷载较小时，预加力对钢箱梁刚度影响较小，当外荷载较大时，预加力对钢箱梁刚度影响较大，钢索在跨中的垂度越大对钢箱梁刚度的提高越大。

Nonlinear analysis of steel box girder with prestressed tendons

To improve the calculation accuracy, nonlinear analysis was conducted to the prestressing and loading stages of a steel box girder with prestressed tendons A nonlinear analysis model was established for the steel box girder with prestressed tendons. The governing differential equation for the steel box girder during prestressing stage was derived following the equilibrium principle and the governing differential equation for the steel box girder during loading stage was derived following the energy principle The theoretical calculations for the mid span deflection and bottom plate strain of the steel girder were found to be in good agreement with the experimental results This indicates that the model and the governing differential equations presented in this paper are correct and efficient Factors that could have effect on the stiffness of the steel girder, such as the magnitude of prestressing force and the vertical position of tendons at the mid span are discussed in detail The discussion results show that when the applied load is relatively small, the effect of the prestressed force on the stiffness of the steel box girder is small; and when applied load is relatively large, the effect is large When the vertical distance at mid span between tendons and neutral axis of the girder is increased, the stiffness of the girder is also increased