Structural behavior of steel, polymer concrete, steel sandwich hollow cylinders under uniaxial compression

The structural behavior of steel, polymer-concrete, steel sandwich hollow cylinders under uniaxial compression has been experimentally investigated. The research is initiated by a literature review that reveals the possible advantages of this kind of composite column.;A polyester-based polymer concrete (PC) is used in this research. Compression tests on plain PC cylinders and aluminum ring-confined PC cylinders are performed. The relationship between the confining stress and the strength of the confined PC and the relationship between the confining stress and the peak strain of the confined PC is established. A two-parameter stress-strain model is modified so that it can be used for both plain and confined PC.;High strength steel tubes with yielding strength ranging from 424MPa to 531MPa are used in the research. Tension tests on coupons and compression tests on tubes are performed. A modified Ramberg-Osgood stress-strain model is developed for the steel tubes. Empirical formulas for inelastic buckling strain and residual strength are also given.;Hollow cylinders of PC, one with an outside steel tube and one with an inside steel tube, are also tested to provide comparisons for the sandwich hollow cylinders.;The test results of the sandwich cylinders indicate that the outer tube can provide confining stress to the PC and the presence of both the outer and inner tubes can change the failure mode of the PC from a brittle one to a relatively ductile one. The load-carrying capacities of the sandwich cylinders are 6.6% to 18.7% larger than those of the summation curves of the three components. The axial strains at the peak load range from 0.70% to 1.22%. The residual load-carrying capacities are 37% to 58% of the maximum load-carrying capacities within the test range.;An analytical model is proposed to simulate the load-deformation behavior of the sandwich cylinder. Based on the test results and simulations, empirical formula for the maximum load-carrying capacity is derived. Empirical formulas for the initial stiffness and the residual load-carrying capacity are also given.