上海S3公路跨大治河桥设计

Design of Shanghai S3 Highway Bridge across Dazhi River

上海S3公路在大治河处采用“主线高速系统+地面系统”的敷设形式。为减少用地面积,降低工程投资,大治河桥设计采用一体化建设、一跨过河的双层简支桁架桥。该桥跨径109 m,采用双层桥面布置,桥宽33.7 m。上部结构横桥向设置4榀桁架,采用三角桁,上、下弦杆及腹杆均采用箱型截面,桁架间采用工字型钢横梁联系,上、下层桥面系采用正交异性钢桥面板。下部结构采用2个分离式的双层门式框架,基础采用钻孔灌注桩;支承体系采用球型钢支座并联叠层橡胶恢复力元件组成的新型组合型减隔震体系。桥面铺装采用浇筑式沥青混凝土,钢结构防腐涂装采用长效型配套体系。采用Midas Civil建立空间有限元模型进行计算分析,结果表明:该桥受力良好,安全可靠,满足规范要求。该桥每平方米桥面用钢指标控制在0.469 t/m^(2),低于同类型桥梁。该桥的设计经验可为同类工程提供参考。

The laying form of "expressway system + ground system in main line" is adopted at Dazhi River in Shanghai S3 Highway. In order to reduce the land area and the engineering investment, the double-deck simple-supported truss bridge of integrated construction and one-span river crossing is adopted in the design of Dazhi River Bridge. The bridge span is 109 m, the double-deck layout is adopted and the bridge width is 33.7 m. Four trusses are arranged in the transverse direction of the bridge superstructure. The trusses are the triangular trusses. The box-shaped section is adopted for all the upper and lower chord rods and belly rods. I-shaped steel beams are used among the trusses. The upper and lower decks are made of orthotropic steel. Two separated double-layer portal frames are used for the substructure, and the cast-in-place piles are used for the foundation. The supporting system is a new type of composite seismic isolation system composed of spherical steel bearing parallel the laminated rubber restoring force elements. The bridge deck is paved with the cast asphalt concrete. The long-term supporting system is adopted for the anticorrosion coating of steel structure. MIDAS Civil is used to establish a spatial finite element model for calculation and analysis. The results show that the bridge has good stress, is safe and reliable, and meets the requirements of the code. The steel index of the bridge deck per square meter is controlled at 0.469 t/m^(2), which is lower than that of the similar bridges. The design experience of this bridge can provide reference for the similar projects.