铁路连续梁桥铅芯橡胶支座优化设计研究

基于最优化理论,以梁体顺桥向位移为约束条件,各墩底最大弯矩之和为目标函数,建立某3跨铁路连续梁桥铅芯橡胶支座(LRB)隔震体系优化设计模型。采用ANSYS中一阶优化方法,进行全桥铅芯橡胶支座动力控制参数优化设计研究。单条地震波输入优化分析表明:连续梁桥中墩和边墩LRB优化参数之间有明显差异,最大差距达42.18%。由于4组单条地震波激励下LRB参数优化解差距较大,进一步以4条地震波作为激励进行支座设计参数优化。结果表明:对于铁路连续梁桥,多条地震波激励下得到的目标函数最优解较单条地震波时更安全。故在实际桥梁减隔震设计中,减隔震支座参数宜采用多条地震波激励下得到的优化值,以确保连续梁桥结构在地震作用下的安全。

Study on Optimal Design of Lead-rubber Bearings for Railway Continuous Beam Bridges

On the basis of the optimization theory,the optimal design model of the seismic isolation system with lead-rubber bearings(LRB) for a 3-span railway continuous bridge was established,considering the longitudinal displacement of the beam as the constraint condition and the summation of the bending moments at the bottom of all piers as the objective function.The first order optimization method in ANSYS was used to realize the dynamic parameters optimal design of the lead-rubber bearings under four earthquake waves.Firstly,the optimal design was carried out with the single earthquake wave as the input.The results show that there are obvious margins between the optimal parameters of lead rubber bearings used on the middle piers and the side piers,and the maximum margin reaches 42%.Then,study on the optimal design with multiple earthquake waves as the input was carried out for the reason that the four groups of optimal solutions with single earthquake wave as the input were quite different.The results indicate as follows: For railway continuous bridges,optimal parameters with multi-earthquake waves as the input are much different from those with single earthquake wave as the input and the objective function with multi-earthquake waves as the input is larger than that with single earthquake wave as the input;in actual projects,optimal design with multi-earthquake waves as the input should be used to obtain the optimum solution and ensure the safety of bridge structures in earthquakes.