ANALYSIS AND DESIGN OF REINFORCED CONCRETE STUB COLUMNS WITH REBAR HRB635 UNDER AXIAL COMPRESSION

In order to explore the performances and mechanisms of reinforced concrete stub columns with hot-rolled high-strength rebars of 635 MPa under axial compression, a finite element analysis model of reinforced concrete stub columns with hot-rolled rebars under axial compression was modelled, and the accuracy of the model was verified based on the results of the axial compression test. Subsequently, the influences of various parameters such as longitudinal reinforcement ratios, stirrup strength and stirrup volume ratios on its axial compression performances were carried out. The bearing characteristics of stub columns subjected to the axial compression process were revealed and the issue of concrete strength matching with high strength rebars was also discussed. Finally, considering the influence of the stirrup strength, volumetric stirrup ratios and concrete strength, the calculation method for predicting the bearing capacity of reinforced concrete stub columns with hot-rolled ribbed high-strength rebars of 635 MPa subjected to axially compressed loads was proposed based on the results of numerical analysis. The results showed that the failure mode of short reinforced concrete columns with hot-rolled ribbed high-strength rebars of 635 MPa mainly displayed as concrete crushing at the mid-height of the column shafts, and the rebar cages were curved like lanterns; the ultimate axial compression bearing capacity of short columns increased with the increase of concrete strength, longitudinal reinforcement ratios, longitudinal reinforcement strength, stirrup volumetric ratios and stirrup strength; in order to take full use of the strength of hot-rolled ribbed high-strength steel bars of 635 MPa, it was appropriate to match concrete with strength above C50; the proposed calculation formula of ultimate bearing capacity could be used in practical engineering.