Experimental and numerical studies on the seismic behavior of steel reinforced concrete compression-bending members with new-type section steel

摘要

There has been no significant improvement on the seismic performance of the ordinary steel reinforced concrete columns compared with the reinforced concrete columns mainly because I- and H-shaped section steel cannot provide sufficient confinement for core concrete. This article presents a study on the seismic behavior of two improved steel reinforced concrete columns by constructing with new-type section steel, a cross-shaped steel whose flanges are in contact with concrete cover by extending the geometry of webs, and a rotated cross-shaped steel whose webs coincide with diagonal line of the column's section. Seismic behavior of the developed steel reinforced concrete columns, mainly including the failure patterns, hysteretic loops, skeleton curves, energy dissipation capacity, and ductility, was experimentally investigated by testing five specimens subjected to low reversed cyclic loading. The test results indicate that both types of steel reinforced concrete columns exhibit bending failure and improved seismic behavior: increased vertical bearing capacity could keep better stability, although yielding of the longitudinal reinforcement and local bucking of flanges happen, and the strength degradation becomes slow and the deformation capacity improves. A finite element model has been established to predict the seismic performance of the developed steel reinforced concrete compression-bending members. The numerical model is validated by the test data, and the numerical results are in close agreement with the experimental ones. A parametric study has been conducted to analyze the effects on the seismic behavior from the axial compression ratio, stirrup spacing, and concrete strength of the developed columns. Eventually, limited values of axial compression ratio for three seismic grades are proposed for the potential design guidance revision and promotion of in situ application.