Experimental And Theoretical Research On Performance Of Irregular Joint Between Steel Box Columns And Beams

In this paper, according to the experimental research of irregular joint between steel box columns and beams, hysteretic characteristics, bearing capacity, ductility, shear deformation, energy dissipation, strength degradation and stiffness degradation rules are studied. Shear failure mechanism of steel irregular joint is analyzed. The failure mode of steel irregular joint is proposed. Deformation mechanism of the steel irregular joint panel zone between steel box columns and beams is established, and the formula for calculation of the yield shear force of the panel zone is proposed. Through analysis on strain and simplified calculation model in the panel zone of steel irregular joint, shear mechanism in the panel zone of steel irregular joint is studied. Based on stress state in the panel zone, the simplified formula is presented for calculating the shear resistance of the steel irregular joint, and the reasonable proposals for design of steel irregular joints are proposed.The experimental and theoretical study results indicate that the irregular joint between steel box columns and beams has good seismic performance and energy dissipation capacity. Ductility is consistent with the requirements of plastic ultimate deformation, and bearing capacity degradation of all the specimens is not notable when the displacement in the layer exceeds ultimate displacement. The experimental results indicate that shear buckling failure in the small core area of panel zone is the main failure mode. The calculation results are consistent with the test results when the height ratio of beams on both sides of column is less than 0.4. The comparison of the experimental results and calculation results show that calculation results of the shear resistance are identical with test results.The study results will provide references for the performance parameters of the irregular joint between steel box columns and beams. Besides, it will provide the theoretical basis for the seismic design of steel irregular joint as well.