Transverse Mechanical Performance Analysis Of UHPC-T Beam

Ultra-high performance concrete(UHPC)is a new cement-based composite material that offers extremely high compressive strength,durability,working performance and toughness,and does not require external materials.It is widely used in bridge engineering,such as T-shaped prefabricated beams and cast-in-place wet joint structures.The new concrete girder bridge has many advantages,including lightweight,no installation of bridge panels,fewer cast-in-place wet joints,and higher durability.It can effectively solve the problems of common concrete T-beam bridge,such as improving the bearing capacity and service life of the bridge.Through systematic theoretical analysis and numerical simulation,the transverse mechanical characteristics of UHPCT girder bridge are comprehensively discussed in order to provide more accurate results.The key points of this study include:(1)The mechanical properties of UHPC materials were studied,and the cube compressive strength,cube splitting tensile strength,axial compressive strength,elastic modulus and bending bending strength of prisms were obtained through experiments.The experimental results show that the mechanical properties of UHPC material are excellent,and the mechanical properties of UHPC material are greatly improved compared with ordinary concrete materials.This paper has certain research significance for the simulation of UHPC-T beam.(2)In order to meet the needs of the current UHPC-T girder bridge,we consider the actual engineering cases at home and abroad,and put forward a new design section size,aiming at maintaining the 30 m maximum span and maximum bearing capacity of the premise,effectively improve the performance of concrete T beam and economic benefits.The results show that although the section size of UHPC-T beam is smaller than that of ordinary concrete T-beams,it has higher elastic ultimate bearing capacity and anticracking strain capacity,and its dead weight is 16% lighter than that of ordinary concrete T-beams,so its service life is longer than that of ordinary concrete T-beams.(3)The purpose of this study is to investigate how different thickness of bridge panels,transverse reinforcement and diaphragm affect the transverse mechanical properties of UHPC-T beams.It is found that the transverse mechanical properties of UHPC-T beams can be significantly improved by strengthening the diaphragm while increasing the transverse reinforcement section area of the bridge.Based on the current bridge standard and theoretical deduction,a new method of cross checking calculation for UHPC-T girder is proposed.(4)By using UHPC wet joint technique,the finite element structure model of bridge was constructed to explore the mechanism of force transfer.Meanwhile,the thickness of wet joint and the length of cantilever were also studied in order to obtain better mechanical characteristics of bridge structure.It is found that the wet joint of UHPC is a method to transfer the load by using the U-shaped end hook of transverse steel bar.Since the depth of the wet joint and the length of the cantilever will have an important effect on the bearing capacity and deformation of the bridge,we recommend that the depth of the diamond-shaped wet joint be set at 120 mm.In addition,it is recommended to set the aspect ratio of the cantilever plate between 6.10 and 9.16.(5)Using functional variational method,the analytical solution of shear lag effect of UHPC-T beam is derived,and its effective distribution width can be calculated.Because the effective width is quite close to the finite element calculation results,the calculated results are accurate,so it can be effectively applied in bridge engineering design to achieve the best results.(6)By establishing the finite element model of UHPC-T girder bridge,the overall mechanical characteristics of the bridge can be deeply explored,so as to better meet the requirements of use.Through the simulation analysis,the UHPC-T girder bridge panel has almost no crack risk when subjected to the action of vehicle load.Using UHPC-T girder bridge,the unique wet joint and diaphragm make the load between the bridge can be transferred effectively,which shows that UHPC-T girder bridge has excellent performance of transverse load transfer.