Experimental And Theoretical Study In Negative Moment Zone Of GFRP Profile-UHPC Continuous Composite Beam

Continuous composite beam bridges are more and more widely used in bridge engineering because of its greater rigidity,higher span capacity,smaller structure height and driving comfort.However,at present,steel-concrete continuous composite beams also face some problems,such as corrosion of steel under severe conditions,concrete cracking in negative bending moment area,etc.FRP,UHPC and other high-performance materials are gradually applied with the continuous development of civil engineering.The GFRP profile-UHPC continuous composite beam,which is made by replacing steel with GFRP profile and normal concrete with UHPC,will have good mechanical properties and durability.At present,there are few literatures on GFRP profile-normal concrete continuous composite beam at home and abroad,and there is no literature on GFRP profile-UHPC continuous composite beam.Therefore,the study on GFRP profile-UHPC continuous composite beams have important academic significance and engineering application value.In this paper,1 GFRP profile-normal concrete continuous composite beam and 8 GFRP profile-UHPC continuous composite beams are tested.The mechanical properties of the negative moment zone of GFRP profile-UHPC continuous composite beam are studied by changing the concrete type,concrete thickness,shear key spacing,reinforcement area and loading mode.The failure modes of GFRP profile-UHPC continuous composite beams are discussed.The main factors influencing the flexural behavior of continuous composite beams and the cracking of concrete in the negative moment zone are studied.And the bending failure mechanism of GFRP profile-UHPC continuous composite beam is revealed.The mechanical properties of GFRP profile-UHPC continuous composite beam are studied theoretically,and the test results are compared with the theoretical results.Finally,the model of GFRP profile-UHPC continuous composite beam is established by ABAQUS software,and the numerical simulation analysis of GFRP profile-UHPC continuous composite beam is carried out.The results show that:(1)GFRP profile-UHPC continuous composite beam has good mechanical properties,and its bearing capacity and crack control are significantly higher than GFRP-concrete continuous composite beam.With the increase of the height of UHPC,the ultimate bearing capacity and stiffness of GFRP profile-UHPC continuous composite beams are greatly improved.With the decrease of bolt spacing,the failure modes of GFRP profile-UHPC continuous composite beams change from the compression failure of the lower flange of GFRP profile at the middle support to the vertical shear failure of the profile at the middle support.If the bolt shear keys are arranged above the middle support,the decrease of bolt shear key spacing can control the development of cracks in the negative moment area.The increase of tensile reinforcement area in negative moment area of GFRP profile-UHPC continuous composite beam can improve the ultimate bearing capacity of continuous composite beam and reduce the crack width in the negative moment area.The loading mode will significantly affect the mechanical performance of GFRP profile-UHPC continuous composite beam.(2)The crack load in the negative moment zone,the bending capacity and shear capacity of the middle support section,the mid-span deflection of GFRP profile-UHPC continuous composite beam and the crack width in the negative moment zone are calculated.The errors between the test value and the theoretical calculation value are small,which provides certain theoretical support for the popularization and design of GFRP profile-UHPC continuous composite beam.(3)Based on the test,the material properties of GFRP profile-UHPC continuous composite beam are defined,and the ABAQUS finite element model of GFRP profile-UHPC continuous composite beam is established.Comparing the numerical simulation results with the test results,the numerical simulation results are in good agreement with the test results.Finally,the parametric analysis of GFRP profile-UHPC continuous composite beam is carried out to provide guidance for the design of GFRP profile-UHPC continuous composite beam.