Study On Mechanical Properties Of Reinforced Concrete Members With High-Strength Steel Bars

HTB650&HTHB900 steel bars perform better than ordinary steel bars.But such high-strength steel bars have little practical use so far,lacking of relative experimental data.In order to promote the new steel bars,we need its' mechanical experimental data urgently,laying foundation of promotion of HTB650&HTHB900 steel bars?In this paper,we will undergo a battery of experiments on properties of concrete with the HTB650&HTHB900 steel bars.The main experimental contents are as follows:1)Through the beam bending tests with HTB650 steel bars acting as longitudinal reinforcement,researching developing level of HTB650 steel bars,collaborative capabilities between high-strength steel bars and concrete,crack development and ultimate load of beam;the formulas of ultimate limit state and serviceability limit state are validated;analyzing specimens by the finite element method,comparing the finite element simulation and experimental results.The results show that: The mechanical characteristics of the beam with high-strength steel bars and the beam with ordinary steel bars are the same;the current bending formulas of ultimate limit state and serviceability limit state are reliable for the beam with high-strength steel bars;the simulation of crack,P-s curve and development of tensile reinforcement's strain corresponds to experimental results well,the simulation of development of stirrup bars' strain has some difference with experimental results,but the overall trend is consistent.2)Through the beam shear tests with HTHB900 steel bars acting as stirrup bars,researching the failure mode of beam,crack development and ultimate load of beam;the formulas of shear capacity is validated;analyzing specimens by the finite element method,comparing the finite element simulation and experimental results.The results show that: The mechanical characteristics of the beam with high-strength steel bars and the beam with ordinary steel bars are the same;the current shear formulas are reliable for the beam with high-strength steel bars;the yield strength of HTHB900 stirrup bars was identified as 360 MPa because of lacking of experimental data.The yield strength will be used in chapter 6;the simulation of crack and development of tensile reinforcement's strain corresponds to experimental results well,the simulation of P-s curve and development of stirrup bars' strain has some difference with experimental results,but the overall trend is consistent.3)Through the axial compression tests with HTB650 steel bars acting as longitudinal reinforcement and HTHB900 steel bars acting as stirrup bars,researching developing level of HTB650 steel bars;in order to establish the calculation method of the peak parameters in confined concrete columns,twenty-six axial compression data of concrete columns confined with stirrups were selected and nine concrete specimens confined with high-strength stirrups were tested under axial loading as supplementary verification;based on the calculation method,the influence of substituting normal-strength stirrups with high-strength stirrups was analyzed;analyzing specimens by the finite element method,comparing the finite element simulation and experimental results.The results show that: the calculating results and experimental results are almost the same;High-strength stirrup bars could enhance the peak parameters of plain concrete and concrete confined with ordinary stirrup bars effectively;the simulation of P-s curve and development of tensile reinforcement and stirrup bars' strain corresponds to experimental results well,but the simulation of concrete's strain has some difference with experimental results,may be due to the concrete is non-homogeneous materials in practice.4)Through pseudo-dynamic tests with HTB650 steel bars acting as longitudinal reinforcement and HTHB900 steel bars acting as stirrup bars,researching structural seismic performance;analyzing specimens by the finite element method,comparing the finite element simulation and experimental results.The results show that: HTB650&HTHB900 could give full play to the role and provide constraint effect well;saving steel bars in the case of mechanical property is almost the same;by simulating monotonic loading,obtain the mechanical properties of reinforced concrete and P-s curve,laying the foundation of restoring force model of high-strength reinforced concrete columns.5)Using the high-strength steel bars for frame structure's reinforcement design,obtain the mechanical and seismic performance through elastic-plastic analysis,providing reliable data for engineering design.