Study On Axial Compression Performance Of GFRP Bars Concrete Middle Long Column

FRP bar is a new-type material.It can be long-term used in execrable situations such as acid,alkali,chloride and humid environment due to its low density,high strength,corrosion resistance,fatigue resistance and other characteristics,which demonstrates the incomparable superiority to reinforcement.Thus it has become an ideal substitute material for steel used in the reinforced concrete structure,which can solve the problem of corrosion fundamentally and improve the durability of concrete structures.Many scholars at home and abroad have done a lot of experimental studies on FRP bars and put forward a lot of useful conclusions,but most focus on the tensile properties of FRP bars and little on their compression performances.With the widespread applications of FRP bars in concrete structures,their role played in the field of civil engineering is growing,therefore it is necessary to study systematically the compression performance and working mechanism of FRP bars in concrete structures.FRP bar includes GFRP bar,CFRP bar,AFRP bar and so on.In this paper,an experiment on the performance of GFRP reinforced concrete middle long columns under axial compression was conducted at first by use of the finite element analysis software ABAQUS to make a finite element simulation analysis,providing a theoretical basis for the experiments.Then eight GFRP reinforced concrete middle long columns were designed and produced,on which an axial compression test was carried out.The impacts of GFRP reinforcement ratio,slenderness ratio and some other factors on axial compression performance of GFRP specimens of reinforced concrete were mainly considered in the test,and test results were analyzed afterwards.The results showed that in the same condition the ultimate bearing capacities of slenderness ratio of 14 specimens reduced in varying degrees compared with those of slenderness ratio of 10 specimens,and the reduction ranged between 2.43%?3.79%;the ultimate bearing capacities of reinforcement ratio of 1.786%specimens increased in varying degrees compared with those of reinforcement ratio of 0.893%specimens,and the increase ranged between 6.6%?8.6%;different from GFRP reinforced concrete short columns,stirrup spacing had little effect on the ultimate bearing capacities of GFRP reinforced concrete middle long columns.During the test GFRP bars played a good compression performance,and worked well together with the overall performance to resist axial compression.Meanwhile,Moreover,the actual ultimate load values of specimen were less than the theoretical values,mainly because the moment due to the eccentricity affected the specimens in the actual course of the test,which resulted in premature destruction of specimens and failure to reach the theoretical ultimate load values.