Numeric Analysis Of Spatial Stress In Pier Top Block Of Long Span Continuous System Bridges

In long span prestressed concrete continuous bridge and continuous rigid frame bridge, the pier top block -as the starting point and foundation in cantilever construction-contains lots of prestressed ducts, and its stress state is very complex. Researches on the tracing simulation of duct stress are less. This paper based on the large space structure finite element program ANSYS, with the background of super large bridge on Baihe river, takes systematic study on distribution of spatial stress over the pier top block.The method is given through trial calculation to divide the complicated spatial structure grids like the pier top block and to simplify the numerical models. The effect of prestressed duct upon the distribution of spatial stress over the pier top block is analyzed and a method resembling simulated circular ducts is proposed. Considering Saint-Venant principle, the length selection of the numerical model of the pier top block is suggested.The paper analyses the space stress of pier top block of Baihe super-long bridge in the construction course,and compared with the measured stress,and the reliability of the numerical simulation method for pier top block was validated.The lognitudinal tangent stress, oblique fissure principal stress and principal compressive stress of pier top block and the variational rule of lognitudinal tangent stress in the landscape orientation of top slab, vertical of web, landscape orientation of Bottom Slab and periphery of diaphragm were studied and stress distribution of pier top block in the construction was obtained.The proposal of the disoisal of stress measure points in the stress monitoring of the bridge was advanced.The weak regional of the pier top block and stress distribution were obtained by analysis of the longitudinal direct stress, principal tensile stress, principal compressive stress under the regular service limit state of long - and short-term load combinations. The structure corresponding measures of component size , reinforcement design and construction of the pier top block were also obtained by analysis of the top-pier-block in construction stage .The conclusion of this article provided some references about calculation and analysis, construction, designing and construction monitoring of pier top block of long span prestressed concrete continuous bridge and continuous rigid frame bridge.