Research On The Effect Of Post-tensioned Prestressed Box Girder Storage Period That Based On ABAQUS

This paper takes the prestressed box girder in actual engineering construction as the research object,carries out relevant technical research on the prestressed box girder,and obtains the technical means of scientific detection and evaluation of the performance of the precast box girder after the storage period and the storage of the girder.Use parameters.With reference to the research methods and conclusions of domestic and foreign scholars on the shrinkage and creep of concrete,a reasonable prestressed box girder model was established through Abaqus;the shrinkage and creep of concrete and the stress relaxation of steel bars were considered to analyze the stages of tensile stress,natural storage,and opening to traffic.Force and deformation of lower prestressed box girder.By analyzing the internal force distribution and change of the box girder at each stage,and the change of deflection,the following results are obtained:(1)The existing modified effective modulus calculation model and creep model calculation can be well applied to the simulation of actual bridge components.The calculation formula considering the joint effect of concrete shrinkage and creep and steel beam creep can be used to define the finite element Concrete creep causes stress loss,and the series function based on logarithmic function can be used to fit the theoretical value of steel beam relaxation in the current code.(2)Adjusting the structure and parameters of the steel reinforcement frame can well check the deflection and force deformation errors during the storage period of the steel bundles.This paper adjusts the model steel frame to reduce the model error from the initial 8.5% to 1.2%.(3)If the storage period of the box girder exceeds 106 days,the deflection of the box girder needs to be controlled.For every offset of 1mm mid-span deflection,a concentrated force of 25 k N must be applied to the mid-span.With the extension of the storage period,the deflection of the box girder increases from fast to slow.After the storage period reaches 300 days,the deflection stabilizes and no longer increases.(4)With the growth of the simulation life of the box girder model,the concrete creep and the stress loss of the steel beam will reach the limit.The fluctuation of the sinusoidal load on the deflection of the box girder will gradually decrease.Due to the effect of the wheel load,the bending The moment and shear force distribution curves will be bent obviously at the wheel load distribution.