The Local Analysis And Rational Design Of PC Continuous Rigid Frame Box Girder Based On Strut-and-Tie Model

As a common type of bridge in bridge construction of China,Continuous rigid frame bridge has advantages in the convenience of cantilever construction,bigger flexural rigidity and better seismic behavior,with the structure characteristics which piers and beams are solidified.Continuous rigid frame bridge has been widely applied in bridge engineering.The box girder as bridge superstructure also has plenty of advantages,such as improving torsional rigidity of sections and better ability under negative moment and better adaptability of modern methods in the bridge construction.Although continuous rigid frame bridge has a huge number of advantages and broading application prospect,most of the designers complete reinforcement design on the basic of their experience due to the lack of current standard,when they designed the local members of cntinuous rigid frame bridge superstructure.In this thesis,the local members of bridge superstructure were designed in the light of an engineering example of cntinuous rigid frame bridge,according to the strut-and-tie model which has been adopted by current standard in foreign country.And co MPared with original design,a more reasonable design method for local members was introduced.The main works of this dissertation are described as follows.(1)The present research status of strut and tie,the calculation criterion of strut and tie model and the basic method of constructing strut and tie model are introduced.(2)The beam element model of the full bridge and the solid model of the block section of the pier are established.The concept of the model deviation coefficient is put forward,and the exact range of the D region in the top block of the PC continuous rigid frame pier is determined,and the three-dimensional solid model of the D region is established.(3)Using the stress trace method,the strut and tie models of upper plate,web plate,bottom plate and diaphragm plate in the D zone and anchorage zone are established.And the internal forces of each rod are solved.(4)According to the strength calculation theory of the strut and tie model,and according to the location of the bar,the reinforcement method based on the strut and tie model is obtained.(5)Compared design result of strut-and-tie model with original design result,a more reasonable design method for local members is obtained.And a more reasonable design method is obtained for PC Continuous rigid frame bridge.