A Research Of Mechanical Properties Of Eccentrically Loaded Coral Concrete Column With CFRP Bars Reinforced

With a great quantity of buildings gradually spring up in coastal islands of our country,the demand of construction raw materials is increased steadily.But most islands are far away from the mainland,if the raw materials of concrete are transported for long distances,it will waste a lot of costs and time.Coral concrete is made of coarse and fine aggregate,and mixed with sea water.Its raw materials can be obtained on the spot except for cement.Meanwhile,the Fiber Reinforced Polymer(FRP)bars are used as structural reinforcement,which is not only qualified for the bearing capacity of members,but also can solve the durability problems effectively such as serious corrosion of steel bars due to the chlorine salt.However,many current researches on FRP bar-coral concrete members are only focused on their adhesion,durability and bending performances,the compressive performances of members are rarely studied.Moreover,the FRP bar and coral concrete are new materials of special constitutive relations and mechanical behaviours,so whether the traditional theories of ordinary reinforced concrete compression members,or the existing findings of FRP bars reinforced concrete columns is not suitable to analyze the mechanical performances of coral concrete columns with FRP bars reinforced.In this paper,the CFRP bars are used as reinforcement of coral concrete columns,and the eccentrically loading performances of specimens are studied.The specific research contents are as follows:(1)The compression properties tests on the CFRP bars were carried out.Based on the effects of slenderness ratios and diameters,the failure patterns,compressive strength,peak strain and compression elastic modulus of CFRP bars were measured and analyzed,then the stress-strain curves and load-displacement curves of the specimens were plotted.(2)The eccentrically loading tests on CFRP bars-coral concrete short columns were carried out.Parameters such as the ultimate bearing capacity,longitudinal stress of CFRP bar,concrete surface stress in the midst of the columns were measured and analyzed.The failure patterns and mechanisms were discussed and compared with ordinary reinforced concrete columns.Subsequently,based on the characteristics of these two materials and the failure patterns of columns,the quantitative analysis of the mechanical properties of CFRP longitudinal reinforcement was put forward,which benefited to the calculation method of CFRP bars-coral concrete short columns.(3)The numerical analysis on CFRP bar-coral concrete eccentrically loaded columns were carried out by ANSYS.Based on the characteristics of CFRP bars and C30 coral concrete,the material units were selected appropriately,and the nonlinear analysis model of eccentric members was properly established.Then relied on this model,the effects of eccentricities,slenderness ratios,longitudinal reinforcement ratios and stirrups spacings on the mechanical behaviors of eccentric members were calculated and discussed.(4)The method for calculating the bearing capacity of CFRP bar-coral concrete eccentrically loaded columns was put forward.Based on the failure mechanisms and numerical simulation results of eccentric columns,the effects of additional total stress of CFRP longitudinal bar and second-order moment on the bearing capacity of members were discussed.Then the calculation methods in existing codes were modified to adapt to the coral concrete eccentric members with CFRP bar reinforced.