Research On The Bending Safety Performance Of Prefabricated Cap Beams With Large Cantilever

At present,the concept of prefabricated assembly of bridges is expanding from the upper structure to the lower structure,and it is developing rapidly in the direction of fully prefabricated bridges.The range of prefabricated components gradually covers the main beam,pier,abutment,foundation,anti-collision wall,cap beams and so on.The prefabricated construction process has been adopted more and more in Europe,America and Japan due to its convenient and rapid construction,stable and reliable quality,and little impact on traffic and environment.The rapid construction of the domestic cap beams started late.In the application of actual engineering,although a large number of new methods and new processes have been put into use,the research on the cap beams has not yet become a systematic status.With reference to the construction technical standards of the US NCHRP,it is urgently needed.According to the needs of the project,the experimental study on the mechanical properties of prefabricated joints and cap beams joints is carried out.The main work carried out on this basis is as follows:1.The cap beams is part of the rapid construction of the bridge project,and the construction technology method is continuously innovated.Aiming at the rapid construction method of cap beams in China,the system is comprehensively classified,and nine types of prefabricated assembled cap beams construction methods are summarized.Detailed construction steps are explained for these construction methods.The analysis and evaluation results show that it is urgent to study the mechanical behavior of prefabricated assembled cap beams and give the best suggestions for construction technology.2.Two assembly schemes of small shear key and large shear key are proposed for the prefabrication of the cap beams.On this basis,three test pieces are designed.Test parameters include the type of shear key and the type of force.The force type refers to uniform loading and eccentric loading.For the force characteristics of the large cantilever cap beams,the large cantilever prefabricated cap beams was loaded during the normal use phase.3.Through the analysis of experimental phenomena and test data,the test results of crack development,failure mode and bearing capacity of each test piece are analyzed.Finally,based on comparative analysis of test phenomena and results of different types of test pieces,research The influence of the size of the key teeth and the type of force on the bending resistance of the test piece is summarized,and the law of the bending failure of the cap beams is summarized.4.Through the study of the force characteristics,failure modes and calculation methods of the large cantilever cap beams,the structural characteristics of the large cantilever cap beams are analyzed.Based on this,the ABAQUS large-scale finite element software is used to carry out numerical simulation analysis on the construction process.In the operation of the bridge,the force of the cap beams is analyzed,and the dimensions of the prestressed cap beams and the calculation of various parameters are studied,which provides reference for the design and application of the large cantilever prestressed cap beams.