Behaviour Of Concrete Filled Double-Skin Steel Tubular Beam-columns With Rectangular Sections

This paper mainly study the behaviour of concrete filled double-skin steeltubular (CFDST) beam-columns, where both outer and inner tubes are rectangularhollow sections (RHS). The research work is summarized as follows: 1. Review The research on CFDST is reviewed firstly. The limits of current researchonCFDST are pointed out. The objectives of the present work and content aredescribed. 2. Tests on rectangular CFDST beam-columns Considering the influences of slenderness ratio and load eccentricity, twelvetests on CFDST beam-columns were carried out. At the same time, six concretefilled steel tubular (CFT) specimens and six empty RHS ones were also tested.Moreover, three stub columns and three beams were tested, which were used tocompare with beam-columns. The manufacturing process and test program areintroduced. The details of the tests are described, and the phenomena are analyzed. 3. Numerical analysis of the load versus deformation relations of rectangularCFDST beam-columns Based on the stress-strain relations of steel and concrete, numerical method isused to analyze the load versus deformation relations of rectangular CFDST. Goodagreements are obtained compared with test results. The effects of loadeccentricity, slenderness ratio, steel ratio, yield strength and concrete strength onM-N interaction curves are analyzed. 4. Simplified models of bearing capacities of rectangular CFDST stubcolumns, beams and beam-columns Based on the parametric analysis, simplified models are derived to predict theload-carrying capacities of the composite members. The predicted results are ingood agreement with those of tests.