Experimental Studies On Cyclic Behavior Of R.C. Beam To Steel Tube Confined Concrete Columns Connections

Cyclic behavior of reinforced concrete (R.C.) beam to steel tube confined concrete column connections are experimentally studied in this paper. The main work is as follows: (1) Eight R.C. beam to steel tube confined concrete column connections and two R.C. beam to concrete–filled steel tubular column connections were tested under constant axial load and cyclically increasing flexural loading. The main parameters in the experiment were section types and axial compressive ratio. The influences of those parameters on the strength, ductility, stiffness, and energy issipation were investigated through analysis of hysteretic skeleton curves. (2) A finite element model, in which geometrical and material's nonlinearity are taken into account simultaneously, was presented to calculate the load versus deformation relations of connections under monotonic loading. The calculated results using the model are generally in good agreement with the experimental results. (3) Based on the theoretical model, the influences of the slenderness ratio, section type, steel ratio, beam-column stiffness ratio, beam-column moment ratio, axial load level on the P-? relations of the R.C. beam to steel tube confined concrete column connections are discussed. (4) Calculation method of the load bearing capacity and the simplified method of the P-? hysteretic skeleton curve of this type of joint are put forward based on the parametric analysis results.