Experimental Research On The Mechanical Characteristics Of Long-span Steel-concrete Continuous Girder Bridges And The Shear Performance Of Composite PBL Shear Keys

The long-span steel-concrete continuous girder bridge is a new type of combined bridge developed in recent years.The main girder of the side span and mid-span fulcrum part adopts the prestressed concrete beam body with relatively large self-weight and rigidity.The middle part adopts a lighter weight steel beam and is connected with the concrete beam body by means of shear keys to form a steel-concrete continuous beam.This structural form can effectively reduce the self-weight of the mid-span structure,reduce the height of the bridge,and increase the clearance under the bridge;the large-span steel girder can further improve the ductility of the structure,avoid the cracking of the mid-span girder,and effectively extend the service life of the bridge;at the same time,the support point The combination of the cantilever pouring of the prestressed concrete beam section and the manufacturing and installation process of the large-span steel box beam can greatly shorten the construction period.The composite PBL shear key is composed of the stud shear key and the PBL shear key,which can better improve the force performance of the shear key,improve the fatigue resistance and seismic performance of the structure,and extend the service life of the structure.Relying on the engineering background of the Hanzhuang Canal Bridge under construction of Xintai Expressway,this paper carried out experimental research on the mechanical characteristics of long-span steel-concrete continuous girder bridges and the shear performance of composite PBL shear keys,and the following research results were obtained:(1)Analysis of the mechanical characteristics of a long-span steel-concrete hybrid continuous beam bridge.Use Midas/civil software to establish the finite element model of the Hanzhuang Canal Bridge,analyze the stress characteristics of the entire bridge during the construction and use phases,and provide a basis for bridge construction control;at the same time,draw the control design of the steel-concrete joint section during the construction and operation phases The internal force value and the internal force value meet the requirements.(2)Experimental study on the shear performance of the composite PBL shear key.In view of the influence of shear key setting penetration steel bar specifications and stud arrangement density on the anti-shear bearing capacity performance,2 sets of 6composite PBL shear key test models were designed and produced to carry out shear key roll-out tests;at the same time,the composite PBL shear key model The experiment carried out finite element analysis to study the good synergistic force characteristics of studs and steel bars,and to verify the accuracy of the test results.(3)According to the finite element analysis and the test results,the results of the finite element simulation and the test results have basically the same changing trends and laws.In the comparison with the stud arrangement density as the changing parameter,the maximum shear capacity is compared with The standard test piece is increased by 32.8%.In the comparison with the diameter of the penetrating steel bar as the change parameter,the maximum shear capacity is increased by 0.35% compared with the standard test piece.It is concluded that the increase of the stud arrangement density in the test is compared with that of the standard test piece.The shear capacity of the specimen is increased by 32.5%,and the increase in the diameter of the penetrating steel bar increases by-0.17% compared with the standard specimen.