Test And Analysis Of Shear Behavior Of Beam Without Web Reinforcement Enhanced By Vertical Prestressing

Concrete girder bridges are a common type of bridge.One of the more prominent problems for box girder bridges with a wide range of applications is the cracking of concrete box girder.The occurrence of oblique cracks in the web is typical.For the cracking problem of the web,this paper proposes a structure that applies the vertical prestress to enhance the shear resistance of the rectangular beam without the abdominal reinforcement,and improves the resistance of the reinforced concrete box girder web.Provide a reference for shear performance studies.In this paper,the experimental and finite element software will be used to analyze and discuss the application of vertical prestressed rectangular beams without web reinforcement.When the analysis results are in perfect agreement,the fullness of the vertical prestressed tunnel grouting,the tension of the prestressed tendons and the spacing of the prestressed tendons are used as parameters to simulate the finite element and shear Performance is coMPared.The specific research contents are as follows:the concrete rectangular beam without vertical prestressing tendons and vertical prestressing tendons is used as a model test to study the deflection of the beam during the shearing process,the crack development,and the concrete in the compression zone.The tensile strength of strained and oblique section concrete,and the final failure form of the beam body;through the experimental data,the force characteristics of reinforced concrete rectangular beams under different parameters are studied.The main contents include load-displacement relationship curve,cracking load,and positive section.And the fracture characteristics and failure modes of the oblique section;Through the three-dimensional finite element software MIDAS/FEA,building and analyzing the models,and the results are coMPared with the experimental results.The collected data repeatedly adjusted the parameters in the finite element model.When the simulation results of the finite element software and the test results were in good agreement,parametric analysis of the model using software to obtain Provide a basis for the shear bearing performance of box girder during actual construction.The main conclusions of this paper:(1)The application of vertical prestress can greatly improve the ultimate shear capacity of beams without web reinforcement.Compared with ordinary beams without web reinforcement,the application of vertical prestress to the shear capacity of test beams is increased by about 120%;(2)Applying vertical prestressing in the body can change the failure mode of the rectangular beam without the abdominal reinforcement,and can increase the ductility of the beam to a greater extent;(3)The fullness of grouting has a certain effect on the shear capacity and ductility of the beam.Compared with the four groups of underfilled beams,the ultimate bearing capacity of full-filled beams is increased by about 4.3%.In addition,research shows that underfilled grouting can cause Premature cracking of the beam and weakening the shear performance of the beam;(4)Different prestressing forces have an effect on the shear performance of the beam.Increasing the tension of the prestressing tendons can improve the crack resistance of the beam,slow the generation of oblique cracks,and improve the shear resistance of the beam to some extent.Carrying capacity;(5)Different prestressing distances have a greater impact on the shear performance of the beam.With the increase of the prestressing distance,the shearing performance of the beam is gradually reduced.About 3%,which shows that proper reduction of the prestressing distance can improve the shear performance of the beam.