基于联合静动力修正模型的斜拉桥换索方案

Cable Replacement Scheme of Cable-Stayed Bridge Based on Joint Static and Dynamic Modification Model

采用梁格法建立了双主梁有限元模型,以联合静动力法实测结果构造了多目标优化函数,采用非支配排序遗传算法进行求解,对运营多年的某混凝土斜拉桥进行了模型修正。基于此,对该桥梁进行了换索的敏感性分析,并通过对多种换索方案进行比较,确立了最优的换索方案。研究结果表明:模型修正后的静力位移和自振频率计算值与实测值吻合较好,能更好地反映出结构实际工作状态;对平行钢丝斜拉索斜拉桥,混凝土主梁下缘拉应力超限是首要考虑的问题,换索存在较大风险,换索前需采用必要的加固措施。

A finite element model of double main beams was established by the grillage method,and a muti-objective optimization function based on joint static and dynamic measurement results was constructed and the function was solved by non-dominated sorting genetic algorithm.The model modification of a concrete cable-stayed bridge that had been in operation for many years was carried out.On this basis,the cable replacement sensitivity was analyzed,and the optimal cable replacement scheme was determined through the comparison of various cable replacement schemes.The research results show that the calculated values of static displacement and natural frequency after model modification are in good agreement with the measured values,which can better reflect the actual working state of the structure.For parallel steel wire cable-stayed bridges,the overrun tensile stress at the lower edge of concrete main beam is the primary consideration.And there is a relatively great risk in cable replacement,and the necessary reinforcement measures should be taken before cable replacement.