Analysis On Bending Performance Of C70 Concrete Simple Support Box Girder

The high performance of high strength concrete can meet the requirements of span and load capacity in bridge engineering.The high durability,good workability,good volumetric stability and economic rationality of its performance are particularly important for the development of bridges.In this paper,the bending strength of high-strength concrete small box girder is studied on the full-scale C70 high-strength prestressed concrete test beam.The bending failure mode,bearing capacity and bending resistance of the beam are analyzed.In this paper,the bending test of the concrete small box girder with C70 strength grade is carried out,and the bending performance of the test beams with C50 strength grade is analyzed and compared.The test beams is analyzed and calculated by finite element method.The main work done is as follows:1)The first part of the article summarizes the application status of high-strength concrete at home and abroad and the problems in the application,and puts forward the research significance and research background of this paper.In the end of the first part,the article summarizes the research objectives and contents.2)The second part puts forward the relevant theories of the experiment,including the material properties,ductility,nonlinear assumption and crack width calculation theory.The material test and the results are summarized.3)In the third part,the loading test of full-scale beam is summarized.And the article analysed the designed parameters,theoretical calculation value,the test point layout and loading method of the test beam.4)In the fourth part,the C50 prestressed concrete small box girder commonly is used as the control to analyze the stress,ductility and crack behavior of two main working conditions(cracking and failure conditions)in C70 test beam loading test.And the bending performance of C70 beam was evaluated.5)In the fifth part,the influence of C70 prestressed concrete small box girder with different prestressing stresses on the bending behavior and the mechanical performance of the beam is discussed.The distribution of the strain in the section and the distribution of the crack in the ductility and load are analyzed.The partial prestressing and full prestressed concrete small box girders were evaluated on the bending performance.This paper studies the bending stability of C70 prestressed concrete box girder under normal use conditions and the ultimate bearing capacity of C70 prestressed concrete box girder.And the mechanical behavior of the beam in the loading test is analyzed and compared.