Study On Wide-box Spatial Effect Of Long-span PC Continuous Rigid-frame Bridge

Because continuous rigid-frame bridge had many advantages,such as stressing definitely,construction costing less than other bridge,application range wide, construction technical maturity and maintenance work less, this bridge style had been widely used in china for recent thirty years.However, no matter at home or abroad, investigations found that some long-span continuous rigid-frame bridges appeared cracks and excessive deflection on the box girders during the using time.Obviously,the reasons to explain these diseases were complicated, lack spatial analysis of the bridge was one of the important reasons. this paper carried out the following researches depending on the Shuitu bridge in Chongqing:â‘ The span of Shui-tu Bridge was large(main span 245m),the cross-section of the box gieder was wide(16.75m), in order to avoid possible diseases that appear during construction or usage time,set up spatial finite element model of the bridge, analysized the spatial effect characteristics of the bridge in construction and normal usage stage.â‘¡Accordance with the wide box cross-section question of long-span continuous rigid-frame bridge, used a plane finite element software to redesign Shui-tu bridge by changing the width of the box cross-section.Set up a spatial finite element model which box girder width was 20.50m based on the Shui-tu bridge.By contrast the shear lag effect and bottom slab horizontal normal stress of the two model,summarized the wide box girder spacial effects characteristics of long-span continuous rigid-frame bridge, gave the limits standard of the wide box girder.â‘¢Accordance with the diseases on bottom slab of long-span and wide-box continuous rigid-frame bridge, summarized the destroying type on the bottom which induced by radial force and analyzed the reasons that led to the bottom destroyed.Derived formula for calculating the radial force.Analyzed the effects of the prestress reinforcement position error,local bending and straight instead of curve etc. on the radial force.Then three types preventive measures effect were compared,at last,gave advice to prevent diseases on the bottom of long-span and wide-box continuous rigid-frame bridge.