高烈度地区不对称刚构-连续梁桥减隔震设计研究

Study of Vibration Mitigation and Isolation Design for Asymmetrical Combined Rigid-Frame and Continuous Beam Bridge in High Seismic Intensity Region

为研究不对称刚构-连续梁桥的减隔震技术,以高烈度地区某(53+130+85)m预应力混凝土不对称刚构-连续梁桥为背景,拟定2种减隔震方案(方案一为非固结墩、台采用单向活动球型钢支座;方案二在方案一基础上,在连续梁侧墩、台处增设液体粘滞阻尼器),优化粘滞阻尼器参数,采用MIDAS Civil软件建立全桥有限元模型,输入3条50年超越概率2.5%的地震波,对比分析2种方案下结构的减隔震效果。结果表明:液体粘滞阻尼器的速度指数α取0.2,阻尼系数C取1800 kN·(m/s)^(-0.2),减隔震效果最佳;与方案一相比,在连续梁侧增设优化参数后的液体粘滞阻尼器(方案二)后,墩底纵向弯矩、墩梁相对位移和梁端位移等得到控制,2号固结墩墩底弯矩降低约50%,1号墩墩梁相对位移减小约54%;方案二可有效地提高桥梁结构抗震性能,减隔震效果明显,作为该桥减隔震方案。

The seismic mitigation and isolation techniques for the asymmetrical combined rigid-frame and continuous beam bridge are studied in this paper,based on the case of a PC bridge of similar type.The bridge has three spans of 53,130 and 85 m,to which two seismic strengthening solutions are proposed.Solution 1 suggests the utilization of unidirectional spherical steel bearings that would not result in fixed girder-pier and girder-abutment connections,and solution 2 advises the addition of fluid viscous dampers at the piers and abutments of the bridge on the base of solution 1 and the parameters of the viscous dampers should be optimized.The finite element model of the overall bridge was established by MIDAS Civil,to which 3 seismic waves with 2.5%probability of exceedance in 50 years was applied,and the seismic mitigation effects of the two solutions were compared.The results show that the fluid viscous damper can display the best seismic mitigation effect,when the speed indexαand damping coefficient C are set at 0.2 and 1800 kN·(m/s)^(-0.2),respectively.Compared to solution 1,when fluid viscous dampers are added to the continuous beam side of the bridge(solution 2),the pier-base longitudinal bending moment,pier-girder relative displacement and girder-end displacement can be effectively controlled,with bending moment in the base of fixed pier No.2 decreased by 50%and the relative displacement between pier No.1 and beam decreased by 54%.Solution 2 can effectively enhance the seismic performance of the bridge,which achieves significant seismic mitigation effect and can be adopted for the bridge.