基于影响矩阵的斜拉桥合理成桥状态索力优化

Comparisons and Analysis of Calculation Methods of Reasonable Cable Force of Cable-stayed Bridge Based on Influencing Matrix

斜拉桥合理成桥状态的确定是设计的关键环节,同时也是后续获取斜拉桥合理施工状态的前提条件。在总结3种基于影响矩阵原理确定斜拉桥合理成桥状态计算方法(未知荷载系数法、最小应变能法和最小弯曲能法)的基础上,以某市政110 m跨径的稀索体系人行斜拉桥为项目依托,建立三维空间有限元模型,结合自编程优化其成桥索力。对比分析3种方法(5种优化目标)优化后的斜拉桥成桥状态索力、弯矩和位移结果,获取各优化计算方法下斜拉桥的力学规律,确定斜拉桥成桥索力最优计算方法,为今后国内外同类桥梁的设计提供借鉴。结果表明:针对稀索体系人行斜拉桥,采用以无约束弯曲能最小为优化目标的计算方法可获取最优索力,斜拉桥成桥后“塔直梁平”、内力均匀、受力合理;采用以3组约束应变能最小为优化目标的计算方法可获取较优索力,斜拉桥成桥索力均匀程度、受力状态仅次于前者;以3组约束弯曲能最小为优化目标和以无约束应变能最小为优化目标的计算方法效果最差,设计时不建议采用这两种优化方法。

The determination of reasonable completion state of cable-stayed bridge is the key link of design,and also the precondition of obtaining the reasonable construction state of cable-stayed bridge.On the basis of summarizing three calculation methods(unknown load coefficient method,minimum strain energy method and minimum bending energy method)for determining the reasonable completion state of cable-stayed bridge based on the principle of influence matrix,a three-dimensional spatial finite element model is established based on the project of a 110 m span thin cable system pedestrian cable-stayed bridge,and the cable force is optimized by self-programming.The results of cable force,bending moment and displacement of cable-stayed bridge after optimization of three methods(five optimization objectives)are compared and analyzed.The mechanical law of cable-stayed bridge under each optimization calculation method is obtained,and the optimal calculation method of cable-stayed bridge completed cable force is determined,so as to provide reference for the design of similar bridges at home and abroad in the future.The results show that for the pedestrian cable-stayed bridge with sparse cable system,the optimal cable force can be obtained by using the calculation method with the minimum unconstrained bending energy as the optimization objective.After the completion of the cable-stayed bridge,the tower is straight and the beam is flat,the internal force is uniform and the stress is reasonable;the calculation method with the minimum constraint strain energy as the optimization objective can obtain the optimal cable force,and the cable force uniformity and stress state of the cable-stayed bridge are only secondary Compared with the former,the calculation method with the minimum of three groups of constrained bending energy and the minimum unconstrained strain energy as the optimization objective is the worst,so these two optimization methods are not recommended for design.