Study On The Influence Factors Of Long Term Performance Of The Cantilever Segmental Prestressed Reinforced Concrete Cantilever Beam Bridge

With the advantages of rapid construction progress and high quality of construction,the segmental cantilever beam bridge is widely used in engineering field.But with the passage of time,a number of problems have also been exposed to the segmental cantilever beam bridge,and the most serious problems are that the cross deflection is too large and there are too many cracks in the web.This paper is based on S-bridge,which is across the Hai-river.It is a segmental prestressed reinforced concrete cantilever beam bridge,and we’ll explore the influence of various factors on the long-term performance.The main research contents include the following aspects:Firstly,several models of creep and shrinkage of concrete are compared based on ones’ theory.Here,we select B3 creep model as calculating model for this bridge,and modify B3 creep model to achieve the purpose of continuous calculation,then verify the modified B3 creep model with the existing test data and it is proved to be correct.JTG D62-2004 shrinkage model is selected to be the calculating model for the contraction,and verify the model to be appropriate with the existing test data;The stress relaxation in United States and Canada norms is selected to be the calculating model for the contraction.Secondly,the large general finite element software ABAQUS is adopted to analyze the modeling the bridge.The type of separated modeling is selected,the con crete element and the prestressed bar element are respectively established,and the ini tial prestress is applied directly by applying initial stress;The static load of the bridg e include the dead load,the load of the crane beam,the lane load.The spring eleme nt is used to simulate the jointed connections.The shrinkage and creep model,and t he relaxation model of the prestressed tendons which are selected before,are writte n in the FORTRAN subroutine,then embedded it in ABAQUS.Results of the long-t erm performance of S-bridge are conform to the expectations.Thirdly,the factors that affect the long-term performance of the cantilever bea m bridge are analyzed,and the sensitivity of the bridge is analyzed by the method of c ontrol variables.The results show that: increasing the length of 0# block,reducing th e number of joints,improving the quality of the joints,and improving the initial stress of the prestressed bar can improve the long-term performance of the segmental cant ilever bridge,and can get a good linear.At the end of the thesis,the construction of th e bridge in design,construction and post maintenance is given: in the design,the 0# bl ock length should be increased as far as possible,the number of joints should be red uced,and the initial stress of the prestressed tendons should be increased.During con struction,the construction quality of 0# block should be emphasized,the constructio n quality of the joints and the deviation of the installation deviation should be emphas ized,and the tension of the prestressing tendons are emphasized as well;In post m aintenance,the joint of 0# block to 1# block and 1′# block should be checked an d maintained in particular.