Research On Flexural Performance Of GFRP-UHPC Composite Beam

In the new era,the people’s ever-growing needs for a better life make a higher level demands for our country’s infrastructure construction with the further improvement of China’s overall national strength.In recent years,a large number of new materials and new structural forms have emerged in the field of civil engineering.The concrete-FRP profile composite beam combines the excellent tensile properties of FRP profiles and the strong compressive properties of concrete.The combination of these two materials make full use of their excellent properties,which will bring this type of combination a bright application prospects in civil enginnering.This paper studies the flexural bearing capacity of ultra-high performance concrete-GFRP I-shaped composite beams,and conducts theoretical and experimental analysis.The specific research contents are as followings:1.8 Concrete-GFRP I-shaped composite beams bending test are made in this paper,2of which using 60 MPa normal concrete and 2 using 100 MPa high strength concrete as well as 4 using 150 MPa ultra-high performance concrete in total.Test parameters in this thesis include concrete strength grade,concrete section size,bolt distance etc..The test results show that the concrete strength grade is positively related to the flexural bearing capacity of composite beams,but the effect of concrete height on the flexural bearing capacity of composite beams is greater than that of concrete strength grade.The CFRP cloth on the section web can effectively improve the overall flexural bearing capacity of the composite beam,and the improvement effect is related to the CFRP reinforced with GFRP.The bolt distance also has an effect on the flexural bearing capacity of the composite beam with a result that closer distance causes a higher bearing capacity with a poor ductility.2.3 single concrete beam or single GFRP profile beam are tested using four point bending method.1 single concrete used 150 MPa UHPC,1 single GFRP profile beam using1 lay of CFRP reinforcement and 1 sigle GFRP profile beam without CFRP reinforcement.The test results show that paving a layer of CFRP cloth can effectively improve the flexural bearing capacity of GFRP I-shaped profiles,and the effect of CFRP reinforcement of GFRP would influence the bearing capacity.3.FEM simulation is carried out in this paper based on the test results in order to verify the applicability of the FEM model,which is used to run the parameter analysis to study the impact of the strength grade of concrete,concrete section dimensions including height and width,bolt distance etc..The results illerstrate that concrete strength grade will affect the bearing capacity of composite beams with a lower influence when concrete strength gets higher.The height of concrete section has a greater affect on the flexural bearing capacity of the composite beam than the increase of the concrete strength grade.The number of bolts will make a little influence of bearing capacity,but more bolts will cause the higher flexural bearing capacity of the composite beam.