Experimental And Numerical Research On Mechanical Performance Of UHPC-T Beam

This article focuses on T-beam research.First,the UHPC-T-beam specimens are tested for the flexural bearing capacity and numerical simulation is carried out;then the finite element model of the T-beam bridge is established,and the vehicle-rail-bridge coupling analysis is carried out.The main research contents are as follows.（1）Designed and fabricated 5 UHPC-T beams with high-strength steel bars and conducted bending load tests.The flexural performance of UHPC T-beams equipped with high-strength steel bars under different reinforcement ratios is studied,and the contribution of steel fibers to the flexural strength and flexural toughness of T-beams is comparatively studied.The influence of UHPC materials with different substrate components on the flexural performance of T beams under the same steel fiber content is studied.Finally,the failure modes and failure modes of the test beams under different mix ratios and different reinforcement ratios are compared and analyzed.（2）Carry out numerical simulation based on material test data.A comparative analysis with the test data verifies the reliability of the test;the flexural load test of the specimen is simulated,and the parameter analysis is carried out.The results show that the amount of steel fiber has a greater impact on the tensile strength of concrete;the change of UHPC base material composition has little effect on the bending performance of the member,while the addition of steel fiber has a greater impact on the failure mode of T-beam;The flexural rigidity and flexural strength of the ascending section of the T-beam increase with the increase of the reinforcement ratio of the high-strength steel bars;the change in the diameter of the steel bar has no effect on the bending cracking load of UHPC when the number of longitudinal bars remains unchanged.（3）The theory of multi-body dynamics and the principle of track irregularity are briefly introduced.The multi-body system of the vehicle is established with reference to the parameters of the motor car body,and the track irregularity is defined.Based on the UHPC-T-beam numerical simulation modeling strategy and referring to the structural parameters of a single-track 32 m T-beam bridge,a T-beam finite element model was established and modal analysis was performed.The rail finite element model is established,the elastic track is generated in the multi-body dynamics software,and the vehicle-rail-bridge coupling system is established based on the T-beam finite element model.（4）The vehicle-rail-bridge coupling model was simulated under four working conditions: 200km/h,250km/h,300km/h,and 350km/h.The dynamic response data of the model was summarized and compared.analysis.The results show that as the train speed increases,the peak value of the vertical dynamic response of the bridge mid-span node gradually decreases.The lateral dynamic response peak gradually increases,and resonance occurs at a certain speed.The dynamic response of the bridge structure calculated in this paper is in compliance with the limit specified by the national standard.rail-bridge coupling system is established based on the double T-beam model and the box-girder model.