沪蓉高速公路铁罗坪大桥设计

Design of Tieluoping Bridge on Shanghai-Chengdu Expressway

铁罗坪大桥主桥为预应力混凝土双塔双索面斜拉桥,跨径布置为(140+322+140)m。该桥主梁基本断面形式为边主梁;桥塔为H形,总高190.397m,塔柱采用空心五边形断面,在上塔柱锚固区采用U形预应力束加强,桥塔墩基础由24根2.4m的桩基组成;每个桥塔两侧布置19对斜拉索,斜拉索采用低松弛镀锌高强钢丝。从温度作用、汽车荷载作用、成桥阶段稳定系数方面对2种结构体系(墩塔梁固结体系和飘浮体系)进行比选,最终选择了对结构受力更为有利的墩塔梁固结体系。采用MIDAS Civil软件分别对该桥静、动力特性、抗风稳定性及地震反应进行分析,分析结果表明结构受力均满足规范要求。该桥主梁采用悬臂浇筑施工,合龙顺序为先边跨、再中跨。

The main bridge of the Tieluoping Bridge on Shanghai-Chengdu Expressway is a prestressed concrete cable-stayed bridge with double pylons, double cable planes and with span arrangement （140＋322＋140） m. The basic section of the main girder of the bridge is the section of edge main girders and the pylons are the H-shape ones, each being 190. 397 m in total height. The columns of a pylon were designed as the hollow pentagonal sections and in the anchorage zones in the upper parts of the columns, the U-shape prestressing strands were employed to reinforce the zones. A foundation for the pylon piers is composed of 24 nos. of 42.4 m piles. On both sides of a pylon, 19 pairs of stay cables, made up of the low relaxation and high-strength galvanized steel wires, were arranged. Two kinds of the structural systems of the rigid fixity system of pier, pylon and girder and the floating system were compared from aspects of the temperature action, truck load action and stability coefficients of the completed bridge and eventually, the rigid fixity system that is more advantageous to the structural force conditions of the bridge was chosen. The software MIDAS Civil was used to respectively analyze the static and dynamic behavior, wind resistant stability and seismic response of the bridge. The results of the analysis indicated that the structural force conditions could meet the relevant requirements in the codes. The main girder of the bridge was constructed by the cantilever cast-in-situ method and the sequence of closure of the bridge proceeded from the side spans first and the contral span late.