Research On Structure And Mechanical Characteristics Of Bridge Prefabricated Assembly Diaphragm

The diaphragm of T-beam bridge is a force transfer member set between T-beams in order to enhance the lateral stiffness of the bridge and maintain the integrity of the bridge structure.It transfers the load to each longitudinal beam through deformation coordination and plays the role of load distribution.The traditional process is to use the cast-in-place way to connect the diaphragm with the main beam on the spot.This method requires a lot of welding and cast-in-place operation after the beam body is set up,which consumes a lot of time and manpower.This obviously runs counter to the concept of high efficiency and environmental protection.In recent years,in order to avoid the disadvantages of traditional construction methods,the prefabricated diaphragm construction method of standardized design and factory production has been gradually adopted in the diaphragm construction of urban bridges.This has strong applicability for the construction of small and medium-span T-beam,I-beam and small box girder bridge.Compared with the cast-in-place concrete diaphragm at the construction site,it can not only ensure the construction quality,but also improve the bridge construction efficiency in an all-round way,which is in line with the construction concept of economic and environmental protection.This paper is based on the prefabricated light simply supported T-beam bridge technology research project of Anhui Traffic Planning Institute and the concrete precast diaphragm connection performance research project of Tongji University.Based on theoretical parameter analysis,model loading test and numerical simulation,this paper focuses on the transverse load distribution of T-beam bridge and the structural optimization and stress of precast prefabricated diaphragm.It mainly includes the reasonable structure form and size selection of precast prefabricated H-shaped steel diaphragm and precast prefabricated concrete diaphragm,etc.The main work of this paper includus the following:(1)Through the use of large-scale finite element software Ansys and Midas civil,the transverse relationship between multiple T beams is simulated and analyzed by solid element and spatial grillage method,and the influence of different modeling methods on the calculation of transverse load distribution is studied.The study shows that the distribution of the reaction force of each T-beam support is the connotation of the lateral distribution of the load.(2)The finite element software Ansys is selected to analyze the parameters of steel diaphragm,and the reasonable thickness and height of H-shaped diaphragm and K-shaped steel diaphragm are studied according to the changes of deflection and stress.The rationality and safety of prefabricated steel diaphragm are verified from the stress of T-beam structure and diaphragm itself.According to the reasonable size recommended by the study,the influence of steel diaphragm design on the lateral load distribution of T-beam is analyzed and compared.(3)Using UHPC as the wet joint material between the diaphragm and the main beam,the load test of the prefabricated diaphragm is carried out,and the mechanical behavior of the diaphragm and the wet joint is studied in order to test the safety and rationality of this structure in an all-round way.(4)The Ansys finite element model of the test member is established,and the deflection and stress of the main beam and the stress state of diaphragm and UHPC joints during loading are analyzed,and the test results are compared.According to the traditional diaphragm force theory,the internal force of the prototype 40m span T beam bridge in the normal use stage is calculated,and the feasibility of the prefabricated diaphragm is compared and verified.