The Optimizational Design Of The External Prestressing Reinforcement Method In Continuous Rigid-frame Bridge

Over the past two or three decades,continuous rigid-frame bridge because of its outstanding advantages widely used in practical engineering.However,after a long period of operation,the construction of continuous rigid-frame bridge for a variety of reasons generally apper varying degrees of box girder cracking and midspan deflection phenomenon.The beam's cracking and deflection influence each other,resulting in a vicious circle,seriously affected the performance of bridge,making tens of thousands of continuous rigid frame bridge into the road tra ffic card neck section,so the reinforcement and maintenance of such bridges become an urgent problem to be solved.On the active bridge is currently the most important reinforcement methods are: external prestressing reinforcement method,bonding steel plates reinforcement method,bonding the carbon fiber board reinforcement method,section enlargement method,bridge reinforcement layer method,changing the structural system method,additional longitudinal reinforcement method and so on.The external prestressing reinforcement is a positive and effective active reinforcement method,it can increase the structure's carrying capacity,improve the midspan deflection and increase the compressive stress reserves of the main beam,this method particularly suitable for the reinforcement of continuous rigid frame bridge which usually are long-span bridges.This paper briefly introduces the common diseases of continuous rigid frame bridge and analyzes the causes of its disease.The main components of the external prestressing reinforcement system,the design points of the reinforcement system and the reinforcement design of the external prestressed cable and the calculation of the prestressed reinforcement members are described.Considering that the linear and cable-force arrangement of the prestressed beam is important for the lifting of the bridge,it needs to optimize.At the same time in order to enhance the overall stiffness strength of the main beam and the reinforcement effect,is bound to put forward an effecti ve reinforcement program.Therefore,this paper focuses on its analysis.In this paper,a multi-span continuous rigid-frame bridge with a span of 96 m + 160 m + 96 m is used as a relying project to analyze the sensitivity of the bridge disease and its genes.The structural damage model was established by using Midas/civil finite element software.For its characteristics of the disease using the preferred external stress to reinforce it.The optimization of the pre-stressed beam layout and its reinforcement program carried out a systematic analysis.The analysis shows that the optimization of the arrangement of the external prestressing is beneficial to reduce the main tensile stress,improve the cross-centerline of the bridge and increase its flexural capacity.The reinforcement method of single in the external prestressing has its limitations.The reinforcement method of single the external prestressing has its limitations,but the disease bridge has complex force and diverse diseases,and only the reinforcement scheme with the combination of external prestressing reinforcement and other reinforcement methods can improve the bearing capacity comprehensively.Effectively solve the bridge of the current disease,to extend the service life of the bridge.