大跨度中承式钢箱桁架拱桥抗震体系研究

为研究大跨度中承式钢箱桁架拱桥合理抗震体系,以某主跨519 m的中承式钢箱桁架拱桥为背景,采用MIDAS软件建立全桥有限元模型,分析桥梁自振特性、非线性时程地震响应,对比采用拉索减震支座前、后2种抗震支承体系下的桥梁地震响应,并对拉索减震支座的自由程进行参数分析。结果表明:对于大跨度中承式拱桥,抗震体系设计应重点关注桥梁支座反力;由于主梁从主拱肋间穿过,降低了桥梁的抗扭刚度;采用拉索减震支座前、后,拱脚内力变化不大,桥梁支座横向水平力最大值由3027 kN降至915 kN,桥梁顺、横桥向位移响应也得到明显改善;该桥合理拉索自由程为5 cm。

Research on Seismic Protection System of Long-Span Half-Through Steel Box Truss Arch Bridge

Based on a half-through steel box truss arch bridge with a main span of 519 m,the appropriate seismic protection system for the long-span arch bridge of similar type is studied.The finite element model of the full bridge was established by MIDAS to analyze the characteristics of natural vibration and non-linear seismic response of the bridge.The seismic responses of the bridge with two types of seismic protection systems were compared,before and after the installation of cable-sliding friction aseismic bearings,and the unstrained lengths of cables in the bearings were analyzed.For the half-through arch bridge,the seismic design should focus on the reaction forces of bearings.Due to that the deck passes through the arch,the torsional stiffness the bridge of such type is relatively discounted,the internal forces of arch springs show slight change before and after the installation of cable-sliding friction aseismic bearings.The maximum horizontal reaction force of the bearing in the transverse direction is reduced from 3027 kN to 915 kN,and the displacement responses of the bridge in the transverse and longitudinal directions are evidently changed for the better.The rational unstrained length of the cables in the cable-sliding friction aseismic bearings for the example bridge is 5 cm.