基于平面框架模型的肋式转向结构简化计算方法

Simplified Calculation Method of Rib Deviator Based on Planar Frames

针对肋式转向结构的受力分析和配筋设计，提出了一种基于平面框架模型的简化计算方法，将转向块所在的箱梁节段转化为平面框架模型，其中顶板、腹板、底板转化为三自由度梁单元，转向结构网式划分为等效梁格．由于顶板、腹板的纵向长度对转向结构受力影响很小，因此取为与转向结构同宽，此时平面框架模型如同倒置的简支T梁，平面框架模型中的底板纵向长度可以通过比拟规范中T梁的有效分布宽度确定，与空间网格模型、ANSYS实体模型的相比，简化方法在绝大多数情况下误差仅为5％-20％，且结果偏于安全．最后，将简化方法应用到国内的两座实桥中并与实桥配筋进行对比，发现实桥转向结构配筋量远大于计算值，配筋偏于安全．此简化方法同样适用于配置双层甚至多层转向管道的转向结构的配筋设计．

A simplified calculation method based on planar frames is proposed for mechanical analysis and reinforcement design of rib deviator. In the planar frame model, top deck, bottom deck and webs of box girder are represented by 3 dof beams, while the rib deviator is equivalent to vertical and horizontal girders. Longitudinal lengths of the top deck and webs can be set the same as the thickness of the rib deviator for its tiny effect on the analysis. Then the planar frame model can be treated as an upside-down T-shape beam, so the longitudinal length of the bottom deck can be obtained by analogy of the effective distribution width of T-shape beam. Compared with spatial grid model and ANSYS solid model, the planar frame model has a good coherence with only 5 %-20 %error in most cases and the solutions are conservative. In the next part, the application results of the simplified calculation method to two practical bridge structures show that the realistic reinforcement amount of the rib deviator is much larger than that by theoretical solution. The simplified calculation method can also be applied to two-layer or multilayer ducts deviators.