Fine Finite Element Analysis And Construction Monitoring Of Frame Pier-Continuous Box Girder Bridge

The stress distribution of prestressed concrete box girder bridge constructed by cantilever segmental method is relatively complex,the finite element model of bar system cannot calculate the real stress of the bridge structure.This paper taked the seventh frame pier-continuous beam bridge of chaoyang overpass main bridge as the engineering background,and studied the stress distribution of frame pier-continuous box girder bridge constructed by cantilever segmental method,the main research contents are as follows:(1)This paper used finite element software Midas/civil and Midas/FEA to establish the finite element model of bar system and the fine simulation finite element model for the frame pier-continuous beam bridge,and calculated the stress during construction stage and the bridge-forming stage.It is found by comparing the calculated results of stress:(1)The stress value calculated by the fine simulation finite element model are all greater than those calculated by the finite element model of bar system;(2)The section stress distribution law calculated by the fine simulation finite element model is quite different from the stress distribution law calculated by the finite element model of bar system in both the transverse and the web height of the box girder;(3)The stress value calculated by the fine simulation finite element model not only reflects the shear lag effect of the box girder,but also includes the local stress under the segment anchor.(2)This paper used Midas/FEA built the fine simulation finite element model to analyze the spatial stress of pier beam of zero block of the frame pier continuous beam bridge in the construction stage and the using stage.Through the analysis of the spatial stress for the frame pier beam,the following is put forward:(1)A certain amount of vertical prestressed bars should be arranged on both sides of the beam in the consolidation area to control the main tensile stress in the using stage;(2)A simplified method for calculating stress of frame pier beam.(3)According to the stress characteristics of the frame pier beam in the construction stage,the tension sequence of prestressed steel of pier beam in the construction is determined.(4)In the cantilever construction stage of box girder,the unbalanced bending moment may cause the torsion of frame pier beam.This paper formulated the balanced method of applying weight,and gived the monitoring measures.(5)By monitoring the stress in the construction of frame pier continuous beam bridge,and comparing the measured data with the theoretical calculated values,it is found that the calculated results of the fine finite element model are closer to the measured values.And it is verified that the stress calculated by the fine simulation finite element model can reflect the actual stress of the structure more accurately.