Experimental Study On The Eccentric Compressive Stub Columns Of BFRP And Hybrid Steel Fiber Reinforced Concrete

Fiber reinforced polymer(FRP)bars have the advantages of light weight,good corrosion resistance and high tensile strength.It is an effective way to solve the problem of steel corrosion by using FRP bars instead of ordinary steel bars in concrete structures.However,due to the low elastic modulus of FRP bars,the problems of large deformation,wide crack and brittle failure exist in the use of FRP reinforced concrete structures.Industrial steel fiber(ISF)has obvious effect on the strength and toughness of concrete,which can limit the development of concrete cracks and improve the brittleness of concrete.However,the cost of ISF concrete is high and the construction is difficult.Recycled steel fiber(RSF)is extracted from waste tires,which has the advantages of high tensile strength and low cost.Hybrid Steel Fiber(HSF)concrete is made by replacing ISF with RSF.Basalt Fiber Reinforced Plastic(BFRP)bars are combined with hybrid steel fiber concrete to form BFRP and HSF reinforced concrete.While solving the corrosion problem of rebar,the mechanical properties of structure are significantly improved and the utilization ratio of bearing capacity of BFRP bars is increased.In order to study the eccentric compressive stub columns of BFRP and HSF reinforced concrete,this paper has done the following research:(1)Based on the 1.0% ISF reinforced concrete,the HSF reinforced concrete is made by replacing the ISF with 0%,25%,50%,75% and 100% RSF respectively.The basic mechanical properties of hybrid steel fiber reinforced concrete are tested.(2)Through the eccentric compression test of 14 stub columns of BFRP and HSF reinforced concrete,the failure mode,crack development process,crack load,extreme load,lateral displacement,strain of BFRP bars and concrete and other mechanical properties and change rules of the test columns with 0%,25%,50%,75%,100%replacement ratio of RSF and 80 mm,40mm,20 mm and 0mm eccentricity respectively are obtained.The results show that the failure of the columns is caused by the crushing of the concrete in the compression zone,and the cracking load and the ultimate load increase with the increase of the replacement ratio of the RSF,and increase with the decrease of the eccentricity.(3)In this paper,ABAQUS software is used to simulate and analyze the test process of the stub columns of BFRP and HSF reinforced concrete,and the simulation results are basically consistent with the test results.Based on the current structural design code in China and the test results,considering the tensile strength of HSF reinforced concrete,the ultimate load of the stub columns of BFRP and HSF reinforced concrete is theoretically derived,and the calculation method of ultimate load is proposed.The results show that the calculated ultimate load is in good agreement with the test results.