Research on Seismic Performance of Partially-Encased Composite Ya-Shaped Steel-Concrete Columns

At present, the application of PEC columns in practical engineering is becoming more and more widespread. Compared with H-shaped steel PEC columns, the bearing capacity of Ya-shaped steel PEC columns is improved while combining the advantages of steel tube concrete columns. In order to study the seismic performance of Ya-shaped steel PEC columns, numerical simulations were conducted on 42 specimens under quasi-static loading by using ABAQUS software, with shear-span ratio, axial compression ratio, horizontal reciprocating loading direction, thicknesses of Ya-shaped steel web plates and flanges as parameters. The simulation results showed that the hysteretic performance of the Ya-shaped steel PEC column was good. The final failure mode of the column loaded in the weak axis direction with a strong axis and shear-span ratio of 1.875 or above was the crushing of concrete at the openings on both sides of the column bottom and the bending failure of the Ya-shaped steel buckling. However, the concrete at the middle of the strong axis column bottom without an opening was also severely damaged, and the weak axis column was not significantly damaged; The concrete at the opening of the weak axis column with a shear span ratio below 1.875 was crushed, and there were cross cracks in the concrete at the unopened position. The concrete at the top of the column was also partially damaged, and the steel section was not buckled, indicating shear failure. Through the analysis of the influence of parameters, it was found that increasing the shear span ratio, thicknesses of flanges and webs could improve the ductility, energy dissipation capacity, and reduce the rate of stiffness degradation of the component, but the peak load decreased with the increase of shear-span ratio; the peak load of strong axis columns decreased with increasing axial compression ratio, while the peak load of weak axis columns increased with increasing axial compression ratio when the axial compression ratio was less than 0.3. Finally, a formula for calculating the seismic bearing capacity of Ya-shaped PEC columns under certain conditions was proposed and modified based on the influencing parameters, verifying the reliability of the revised formula and providing a reference for the application of Ya-shaped steel PEC columns in engineering.