A HYSTERETIC MODEL OF MOMENT-ROTATION RELATIONSHIP FOR PLASTIC HINGE ZONE OF FRP-CONCRETE-STEEL DOUBLE SKIN TUBULAR COLUMNS

Clough’s bilinear hysteretic model is adopted to be the hysteretic model of the moment-rotation relationship of plastic-hinge zone of FRP-concrete-steel double-skin tubular columns (DSTCs). Formulas of calculating moment and rotation at two control points of the skeleton curve, which are the yield point and the ultimate point, are derived. Based on the developed hysteretic model, the yield moment and the ultimate moment of the cross section, the yield displacement and the ultimate displacement at the lateral loading point, and the lateral force-displacement hysteretic curves of nine DSTC specimens are calculated. The calculate results agree well with the test results.