Numerical Analysis And Load Test Of Externally Prestressed Continuous Rigid Frame Bridge In Operational Stage

With the rapid development of highway system in China and the advancements in bridge cantilever construction technology,long-span prestressed concrete continuous rigid frame bridge has become an increasingly popular choice for engineers.Minimal bridge expansion joints needed,smooth bridge deck floor,improved flexural strength along longitudinal direction,improved torsional stiffness along transverse direction,and good resistance to seismic loading are the advantages of this bridge type.However,due to the lack of vision into future predictions and the lack of timely update of the old specifications and regualtions,or the existence of errors during construction,the bridge structure is likely to experience capacity overload during service time and the flexure at the main span of the continuous rigid frame bridge will reach its ultimate value.Therefore,it is necessary to study all possible causes of this deflection and methods of reinforcements that can restore the bearing capacity of the bridge.This paper focuses on the deflection of a continuous rigid frame bridge in Heilongjiang,and studied the flexural load capacity calculation of bridge after external prestressing reinforcement,the increase in prestress,the loss in prestress,as well as constructed the FEM of the original bridge,damaged bridge and the reinforced bridge and analyzed the reinforcement effect through load testing.The main content of this article includes:Demonstrated calculation method and calculated the flexural strength after external prestress reinforcement,the stress increment of external prestress,the loss of external prestress and the elongation length of external steel wire ropes;Obtained factors that are most influential on deflection of continuous rigid frame bridge by analyzing prestress loss,stiffness reduction,shrinkage and creep,shear deformation,external prestress loss,and capacity overload;FEM of the bridge before reinforcement,after damaged and after reinforcement was constructed respectively and analyzed based on the reinforcement design scheme and using deflection as control;Loading tests were conducted for the bridge before reinforcement,atfter reinforcement and after 6 years of operation to evaluate the performance of external prestressing reinforcement technique.