Experimental Study On Flexural Capacity Of Ultra-High-Performance Concrete (UHPC) Beams

Ultra-High Performance Concrete(UHPC)is a new cement-based composite material with significant advantages such as high strength,high toughness and good durability,which is perfectly in line with the current concept of environmental protection and sustainable development.Especially in the field of bridges,UHPC provides stable support for bridges to achieve long life,large span and lightness with its outstanding performance advantages,With the addition of steel fiber,the cracks of UHPC components can be better limited.When studying the flexural capacity of UHPC components,the tensile effect of UHPC needs to be considered.However,the opinions of scholars at home and abroad on how to calculate the tensile contribution of the cracked part of UHPC have not been unified,thus further research is necessary.Taking the reinforced UHPC-T-shaped beams as the research object,this paper introduces the whole process of design,construction and experiment,studies the failure mode,load-deflection curve,crack and other bending properties of UHPC beam under different reinforcement rate conditions,establishes the calculation formula of bending resistance of UHPC beam,and uses the material test data to carry out finite element simulation.The main research contents of this article are as follows:1.Five UHPC beams was designed and manufactured,and the experimental research was carried out with the longitudinal reinforcement ratio as the test parameter.The results show that the cracking load of the component is less affected by the longitudinal reinforcement ratio,while the yield load and limit load increase to varying degrees with the increase of the reinforcement ratio.2.The test data was analyzed and the cracking moment,bending stiffness,crack width,minimum reinforcement rate and limit reinforcement rate was calculated;The calculation method of flexural capacity of UHPC-T beams in Chinese and foreign specifications was checked;The ultimate flexural capacity formula of the UHPC-T beams was derived.The calculation results are basically consistent with the measured value of the test,and checked the 60 UHPC beams in the Chinese and foreign literature,the gap between the calculated value and the test value is small.3.ABAQUS software was used to carry out finite element analysis of the static loading process of the beams with the material test data.The damage form,load-deflection curve and crack pattern are basically consistent with the test results,which verifies the effectiveness of the model.And increase the steel bar grade to study the impact of the steel bar grade on flexural performance of UHPC beams.The results show that when the HRB400 steel bar is replaced with HRB500 steel bar,the bending capacity is increased by about 22% while reinforcement rate remains unchanged.Increase the compressive strength and tensile strength of UHPC respectively,and the flexural capacity of UHPC beams are slightly improved.