Experimental Study And Calculation Method On Connection And Anchorage Performance Of Grade 600MPa High Strength Rebar

Grade 600 MPa Hot-rolled Ribbed High Strength Rebar(HRHSR)also called as High Strength Rebar(HSR)is a new type of steel rebar offering high yield stress and excellent ductility.Through these excellent characteristics,it should be well adapted in application of modern engineering and meet the requirements of technicians for the sustainable development of the construction industries and green architectural materials.Advances in material science led to the production of HSR that has enhanced corrosion resistance,full reserve capacity,material saving,and higher strength compared to conventional Grades of steel rebar.Researchers have conducted huge studies on the bonding-anchorage properties of steel rebar and concrete,but mainly focused on ordinary steel rebar with strengths of 500 MPa or less,but there is a lack of research on the bond-anchorage performance of HSR and concrete.With the promotion of high-strength steel bars in China,HRB500 steel bars have been incorporated into the current “Code for Design of Concrete Structures”(GB50010-2010),and the promotion and application of 600 MPa HSR is highly imperative.High strength material can lead to more economical design reducing the material requirements for a particular project and expanding its life span.The research and application of 600 MPa HSR is not only very important for China's energy saving and emission reduction,it also marks that the construction industry in China is once again opened up by advanced steel rebar.However the researches on Grade 600 MPa HSR still need to be studied deeper in China.This research is aiming on problem of connection and anchorage performance of Grade 600 MPa HSSR.A total of 417 connection and anchorage specimens were investigated.And the parameters affecting them such as anchoring length,stirrups ratio and concrete cover size,concrete compressive strength,bending angle and mechanical modes were analyzed.The main work is summarized as follows:1)141 tensile specimens were carried out to study the connection performance of Grade 600 MPa hot-rolled ribbed high-strength steel.The research parameters were anchoring lap length,spacing stirrups ratio,concrete cover size,bar size,concrete compressive strength,welding methods and sleeve types.The mechanical properties and failure modes of Grade 600 MPa HSR under different anchorages were investigated in detail.2)Through the statistical regression analysis of the four lap splice types,the tiejoin connection,the welded joint,the sleeve connection,and the flash-welded joint test data,the connection anchorage limit bond between the 600 MPa grade highstrength steel bar and the concrete is obtained.The formulas for calculating the strength of all types of connection were presented.3)274 pull out specimens were designed and studied to investigate the bondanchorage performance of Grade 600 MPa hot-rolled ribbed HSR.The research parameters were anchoring length,spacing stirrups ratio,concrete cover size,bar size,concrete compressive strength,bending angle and mechanical anchoring types.The mechanical properties and failure modes of Grade 600 MPa HSR under different anchorages were investigated4)Through the statistical regression analysis of the five types of bonded anchors,namely straight anchor,hooked anchor,threaded head nut anchor,one-side welded head anchor and double-sided welded head anchor test data,the connection anchorage between 600 MPa high strength steel and concrete is obtained.The ultimate bond strength calculation formulas were proposed..