Bond Properties Between HRB600 Steel Bar And Steel Fiber Reinforced High-strength Concrete

To pursue a green environment in current society,the sustainable development has become an inevitable trend in the engineering construction.The use of high strength steel bar can effectively reduce the amount of steel and save resource for protecting the environment.Meanwhile,high strength steel bar can increase the durability and reliability of structures,and meet the requirements of engineering construction and design for large structures and heavy load structures.Therefore,the application of high strength steel bar is advantageous to economic benefit and social benefit.However,the theory and applications of HRB600 steel bar have seldom been studied,which has hindered the use of HRB600 steel bar.The bond properties between steel bar and concrete are the basis for their compatible work.The study of bond properties of HRB600 steel bar embedded in concrete has crucial significance for the application of HRB600 steel bar in engineering.In this study,the local bond test was conducted to investigate the effects of concrete strength,volume fraction of steel fiber,bar diameter,thickness of concrete cover and bond length on the bond properties between HRB600 steel bar and steel fiber reinforced high strength concrete(SFRHSC).The main contents of this thesis are listed as below.(1)The pullout test of 42 local bond specimens of HRB600 steel bar embedded in SFRHSC was carried to investigate the effects of concrete strength,volume fraction of steel fiber,bar diameter,thickness of concrete cover and bond length on the initial bond strength,ultimate bond strength and free end slip at ultimate bond strength for HRB600 steel bar embedded in SFRHSC.Then,the bond-slip(free end and loaded end)curves affected by various factors were obtained.(2)By using the strain gauges attached in steel bar,the distributions of bond stress and relative slip for HRB600 steel bar embedded in SFRHSC were derived from the measured strains.Afterwards,the distributions affected by varying volume fractions of steel fiber,thicknesses of concrete cover and bond lengths were analyzed.Also,the bond stress-relative slip curves at different bond points were achieved by using the distributions of bond stress and relative slip.(3)Based on the regression analysis of test results,the calculation formula for bond strength of HRB600 steel bar embedded in SFRHSC was proposed,which considered the factors of concrete strength,volume fraction of steel fiber,relative thicknesses of concrete cover and relative bond length.Then,the bond-slip constitutive model of HRB600 steel bar embedded in SFRHSC was obtained.