Finite Element Analysis And Construction Monitoring Of Continuous Rigid Frame Bridges With External Prestressing Reinforcement

With the rapid development of traffic and transportation,a great increase in the application of long span prestressed concrete(PC)continuous rigid frame bean bridges.The advantages of this bridge type are:expansion joint not required,comfortable driving experience,ease of construction without the bearings,integrity maintenance,great stiffness and uniform distribution of stress.However,most of the PC continuous rigid frame beam bridges have experience member deterioration of some degree such as deflection at midspan,concrete cracking and stiffness reduction after many years of operation,which seriously affect the safety and durability of the bridge.The external prestress reinforcement is an active and effective method of active reinforcement,which can effectively improve the ultimate strength,stiffness and crack resistance of the structure.The external prestress reinforcement is convenient in construction,high in efficiency and highly cost-effective,thus has been widely applied in practical reinforcement projects.With the development of bridge reinforcement technology,construction methods have became more and more meticulous and complex.Therefore,the importance of real-time tracking and monitoring in bridge reinforcement construction process has become more prominent.This paper takes a continuous rigid frame beam bridge as the engineering background.According to its bridge type and construction characteristics,the software MIDAS/CIVIL was used for finite element modeling and theoretical and numerical analysis.The optimal construction method for the bridge was determined and the adaptive control method was used in construction control of the bridge.The main contents are as follows:1.The development of external prestressing reinforcement technology at home and abroad,and the main theoretical results accomplished along with the evaluation of' the bridge were discussed in detail.The design theory of external prestressing reinforcement structure system,tension stress control,effective prestress loss and external prestressing arrangement were also elaborated in detail.2.The latest advances of construction monitoring and research at home and abroad were discussed.The fundamental theory,construction control methods,numerical analysis theory,and parameter identification methods of external prestress reinforcement method were explained.3.The structural bearing capacity of the original bridge was verified,and the deflection fitting method was used to predict the actual damage state of the bridge,which acts as the theoretical and numerical basis for reinforcement calculation design.At the same time,the reinforcement process of the steel plate posting and external prestress were analyzed though finite element modeling.It is concluded that the reinforcement of the external prestress was able to improve the bearing capacity and deformation condition of the bridge effectively.4.Analyzed the influence of different tendon arrangements and tensioning methods on the stress and deformation of the reinforced bridge,mainly from the perspective of the prestressed cable steering device and the simultaneous stretching of symmetrical but different spans,and the optimal construction scheme were derived.Different tension stresses and their impacts on displacements of beams and piers were also analyzed.5.Through the construction process and the load bearing characteristics of the bridge,the finite element model of construction control was constructed to determine the optimal bridge reinforcement design.The structural stress characteristics and deformation status of the key construction stage were analyzed,and the field construction control was carried out according to the theoretical and numerical results.The structural stress,curvature,and cable force after the reinforcement construction was compared and contrasted.Satisfactory construction control results were obtained.