梁拱组合人行天桥三维地震响应特性分析

Analyses of Three-dimensional Seismic Response Characteristics of Beam-arch Combination Pedestrian Bridge

梁拱组合人行天桥是典型的空间结构,由于跨越结构重心高度高于桥面,其地震响应特性将与常规人行天桥存在较大差异。为了探究梁拱组合人行天桥的地震响应特性,以某梁拱组合人行天桥为研究对象,运用Sap2000建立了空间动力计算模型,采用非线性时程法详细研究了该梁拱组合人行天桥的地震响应特性及其影响因素。结果表明:竖向地震对梁拱组合人行天桥产生不利影响,必须考虑竖向地震的三维地震响应分析才能充分反映其地震响应特性;跨越结构相对位移响应较大,墩的响应较小,墩的抗侧移能力发挥有限;跨越结构地震稳定性较差,地震中容易发生倾覆落梁;梯道、支座滑动性能和跨越结构重心高度是跨越结构地震稳定的重要影响因素。

Beam-arch combination pedestrian bridge is a typical spatial structure, and as the center height of its gravity always above deck, there will have a big different to the seismic response characteristics of conventional pe- destrian bridges. In order to explore the seismic response characteristics of beam-arch combination pedestrian bridge, taking a beam-arch combination pedestrian bridge as the research object, finite element dynamic analysis model was established by Sap2000, with nonlinear time history analysis method, effects of vertical seismic and other factors on the seismic responses of the pedestrian bridge were researched and seismic problems of the same bridges were revealed. Results show that vertical earthquake exert an adverse effect on the seismic performance of pedestri- an bridge and three-dimensional seismic response analysis must be conducted to accurately reflect its seismic re- sponse. The relative displacement response of the across structure is bigger and the response of piers is smaller. The seismic stability of the across structure is poor, and it prone to overturn and beam falling-off. Staircases, slid- ing performance of bearings and the center height of across structure＇ s gravity are important influencing factors of the seismic stability of the across structure.