大跨径连续钢桁架拱桥设计与分析

Design and Analysis of a Long-span Continuous Steel Truss Arch Bridge

宝鸡市植物园渭河大桥为(65+158+65)m的三跨连续钢桁架拱桥,桥宽30m。主桁材质为Q345qD,由边跨平弦桁梁和中跨钢桁架拱组成,横向两榀桁架间距24m,采用整体式节点,腹杆与上下弦杆焊接连接,无预应力系杆。横向联接系采用两节间一组的间隔布置稳定系统,提高了桥梁.上方空间的通透性。桥址位于高烈度区,采用了摩擦摆式减隔震支座+弹塑性钢阻尼元件耗能的减隔震体系。地震响应分析显示,减隔震体系有效的减小了下部结构所承受的地震力,达到了设防标准。横梁计算表明,车辆荷载横向局部加载应考虑折减系数,依据车道布载系数折减偏小,本桥六车道折减系数取0.9,保证了结构的安全性。

The Weihe River Bridge in Baoji Botanical Garden is a three-span(65m+158m+65m)continu-ous steel truss arch bridge with a bridge width of 30m.The main truss was made of steel Q345qD,and it is composed of two side spans with flat chord truss girder system and one mid span with steel truss arch system.The spacing between the two transverse trusses is 24m.Integral joints are used,the web members are welded to.the upper and lower chords,and there are no prestressed tie rods.The transverse connection system uses a spaced arrangement with a group of two sections as an interval,which improves the permeability of the space a-bove the bridge.Since this bridge is in a seismic high-intensity area,the friction pendulum vibration and isola-tion bearings,and the elastic-plastic steel damping element are used for energy dissipation.The seismic re-sponse analysis results show that the seismic isolation system effectively reduces the seismic force on the sub-structure and meet the fortification criteria.The calculation results of the crossbeam show that the reduction fac-tor should be considered for the lateral local loading of the vehicle load.According to the lane distribution fac-tor,the reduction factor of this six lanes bridge is taken as 0.9 to ensure the structure safety.