时速350 km高速铁路40 m跨度预应力混凝土简支箱梁徐变上拱控制设计研究

Design Research on Creep Camber Control for 40 m Span Prestressed Concrete Simply Supported Box Girder on High Speed Railway at 350 km/h

高速铁路跨度40 m简支箱梁由残余徐变上拱控制结构设计。在全预应力体系范围内研究了采用降低跨中底缘压应力、提高预应力合力中心高度、缩短底板预应力束长度、增加梁高、提高混凝土强度等级、推迟二期恒载上桥时间、细化二期恒载分级等7种方法降低梁体残余徐变上拱的效果及适用性。受施工条件、技术经济性等因素限制,建议不采用前5种控制方法,而采用推迟二期恒载上桥时间和细化二期恒载分级的方法来控制40 m跨度简支箱梁残余徐变拱度。

For residual creep camber controls the design of high speed railway simply supported box girder with span of 40 m,o n the condition of full prestressed system,the effects and applicabilities of seven methods to reduce the residual creep camber were researched, such as reducing the compressive stress of girder bottom atthe middle span,increasing the centre heightof prestressed force, shortening the prestressed tendon length in bottom board, increasing the girder height, improving the concrete grade,delaying the construction of subsidiary facilities and refining the classification of secondary dead load.The results show thatthe firstfive control methods are notsuitable due to the limitfactors of construction conditions and technical economy.Both of the lasttwo methods are adopted to reduce the residual creep camber of simply supported box girder with span of 40.