轨道交通(90+160+90)m矮塔斜拉桥设计

Design of (90+160+90)m Extradosed Cable-Stayed Bridge on Rail Transit

某轨道交通线路斜交跨越既有省道高架桥工程,采用跨径布置为(90+160+90) m预应力混凝土矮塔斜拉桥的结构形式,支承体系为塔梁固结、墩梁分离,主梁为单箱双室变高度预应力混凝土连续梁,桥塔为"A"字形钢筋混凝土结构,桥塔有效高度为20m,有效高跨比为1∶8;斜拉索采用1860MPa环氧涂层钢绞线,穿过桥塔上的分丝管索鞍,在主梁上锚固;支座采用大吨位波浪形钢阻尼减隔震支座,在解决桥梁抗震问题的同时,大大减小了下部结构的尺寸和配筋,提升了桥梁整体的景观效果。基于矮塔斜拉桥索梁活载比特性,确定了合理的斜拉索索力和主梁预应力的设置,通过车-桥耦合的动力分析,本桥的动力特性和列车过桥时的安全性、舒适性均满足规范要求。

The skewed rail transit line strides over the existing provincial highway viaduct and adopts a prestressed concrete extradosed cable-stayed bridge with spans of( 90 + 160 + 90) m. The supporting system is pylon-girder consolidation and pier-girder separation. The main girder is double-celled single-box prestressed concrete continued girder with variable heights. The bridge pylon uses A-shaped reinforced concrete structure,which effective height is 20 m. The effective height span ratio is 1 ∶ 8. 1860 MPa epoxy coated steel wires are used for stay cable,those are anchored to the main girder after passing through the split tube cable saddle area on the pylon. The wave shaped steel damping of large tonnage seismic isolation bearing solves the seismic problem of bridge,at the same time,it reduces the size and reinforcement of the substructure greatly and improves the overall landscape effect of the bridge. Base on the live load ratio characteristics of extradosed cable-stayed bridge,it determines the reasonable cable force of stay cable and prestress of main girder. According to the vehicle bridge coupling dynamic analysis,not only the dynamic characteristics of the bridge,but also the safety and comfort of the train when crossing the bridge meet the specification requirements.