Study On Mechanical Behaviors Of Prestressed Concrete Curved Box-Girder Bridges

The curved bridges are widely used in freeway, highway in mountain areas, and interchange bridges in urban for the advantages of beautiful line style, reduction of use of land and good conditions for vehicles. At present, the America, Canada and other countries have developed relevant specifications or codes for curved bridges, but the design and construction specifications of curved bridges in China have not yet been made. The America has carried out fairly systematical researches on steel I-girder curved bridges and concrete box-girder curved bridges. In recent years, some scholars in China have also made many achievements on theories of curved bridge, but there are still many problems in engineering applications. For the status of "widely used, many problems, weak researches and without specificatons" of curved bridges, the background of this paper is the research project of "Structural Mechanics Behavior and Design Methods of Curved Continuous Bridge". The prestressed concrete curved box-girder bridges are used to be research objects for the total paper, the main respects of the work as follows:The first chaper mainly introduced the development status in applications of the curved bridge projects, theoretical researches, numerical analysis, experimental studies and summarized the problems which arise in the design and construction stage of curved girder bridges.The second chapter established single girder models, grillage models and spatial shell element models by use of the ANSYS parametric design language (APDL) provided by ANSYS to analyze how to build a rational finite element model for curved bridges.The third chapter built finite element models of a total of 12 prestressed concrete curved continuous girder bridges with three span arrangements (30+30+30m, 30+40+30m, 40+50+40m) and four bridge widths (B=8.5m, 12.5m, 16.5m and 24.5m) according to the engineering practice and then studied the relationship of displacements, internal forces and supporting forces with the main geometric parameters under dead loads and vehicle loads.The fouth chapter derived the prestressed equivalent loads calculation formula of the curved bridge and developed the prestressed equivalent load calculation program. Then, taking curved bridges with two bridge widths (B=8.5m, B=16.5m) as example, the parameter analysis on prestressing action was conducted. Two methods were given to solve the problem that the torsion angle and torque was too large with the symmetric layout of steel bundles for the continuous curved girder bridges with small curvature radius.The fifth chapter firstly conducted the parameter analysis of curved girder bridges under the uniform temperature actions. Then the surface temperature field computing theory for concrete curved box-girder bridges was introduced and the surface temperature computing program of curved girder was developed using Visual C++. Finally the hot-structure coupling effects were studied under the thermal action of sunshine by the help of the ANSYS finite element analysis software.