Study On The Torsion Of Prestressed Concrete Continuous Curved Box Girder And Reinforcement Method

Continuous prestressed comcrete curved box girders have been widely applied in a huge cloverleaf junction of arterial traffic projects. However, the diseases due to torsion deformation of the curved box-girder may not only have a heavy influence on the bearing capacity of the structure but also lead to safety accidents.In order to study the influence of the torsion deformation of a curved box girder on its structure nature, the status quo, machaniccs nature, design principles and calculation methods of curve bridges are reviewed, with special reference to continuous prestressed comcrete curved box girders.A case history, pertaining to the evaluation, analysis and reinforcement of the diseases due to the torsion deformation of the curved box girders of Beihailu cloverleaf junction (bridge) in the Tianjin Economic-technological development area, is presented, in terms of followings:(1) site investigation on the diseases, (2) finite element method (FEM) analysis on the influence of the gravity, centrifugal effect, brake and temperature forces, position of bearings, on the bridge mechanical features, (3) loading test on the static and dynamic parameters of the bridge to evaluate its the mechanical nature, integral stiffness as well as performance in practice.Based on the results above mentioned, the nature of the deficiency and its reason of the Beihailu bridge is proposed, and the influence of the deficiency on the uasage and bearing capacity of the bridge is accordingly assessed. The analysis results are applied to the bridge reinforcement design.The measures of the brdge reinforcement and its optimization are described from blueprint to being put in practice. The effect of the reinforcement measures is also presented following up the scent for five years.