[This article belongs to Volume - 55, Issue - 01]
Gongcheng Kexue Yu Jishu/Advanced Engineering Science
Journal ID : AES-18-01-2023-497

Title : Prediction of long-term behaviour and Prestress loss of Balanced cantilever PSC box girder bridges
Sabarigirivasan.L, N.Umamaheswari,

Abstract : Long-term impacts on prestressed segmentally erected balanced cantilever bridges frequently result in greater deflections than predicted. Creep and shrinkage which occurs in the concrete deck of Prestressed Concrete (PSC) box girder bridges, can lead to a considerable redistribution of loads as well as an increase in bending moments across continuous supports, resulting in a rise in deflections. Since the cantilevers and the middle part have a peculiar static arrangement, creep deflections in this situation are constantly evolving, notably at the extremities of the cantilevers and the middle part. Traffic movement on the bridge will be made more difficult with these extreme deflections, which can lead to a collapse of the structure. In the current study, prediction models of PSC bridges using Free Cantilever Method in view of the long-term effects were proposed and discussed. The static systems of the structures were changed to achieve this goal by introducing different grades of concrete and steel tendons, which play a major role in creep, shrinkage and progressive cracking of concrete deck. Creep and shrinkage evaluations are considered as the critical factors in simulation and analysis of free cantilever bridge, particularly in the case of cast-in-place segmental bridges that demands for extensive prestressing. MIDAS Civil software was used to create 3-D finite element (FE) models of the specified bridges, which includes the implications of static and dynamic load applications, creep and ageing of concrete. It is possible to simulate construction phases, the effects of time-dependent material displacements and improvements to the bridge's structural system using the stage process approach. It is necessary to modify equations available in practice when utilising the free cantilever technique to construct bridges in order to account for time-dependent deformation and stress redistribution. Results from the current approach and numerical analysis are in good agreement with each other.