Performance Investigation Of FRP-concrete-steel Double-skin Square Columns Under Eccentric Compressive Loading

Hybrid FRP-concrete-steel double-skin tubular columns (hybrid DSTCs) are a new form of hybrid columns recently proposed by Prof. J.G.Teng in The Hong Kong Polytechnic University. The column consists of an outer tube made of fiber-reinforced polymer and an inner tube made of steel, with the space between filled with concrete. It has the following advantages:light weight, easy construction, corrosion resistance, Ductility and seismic behavior, etc. Based on experimental and theoretical analysis, the mechanical behaviors of the FRP-concrete-steel double-skin square columns under eccentric load are researched. The major contents and results are as follows:(1) Nine FRP-concrete-steel double-skin square columns have been designed in the experiment. The paper mainly describes the design scheme and the process of manufacture and the loading scheme of these columns.(2) Tests of FRP-concrete-steel double-skin square columns under axial load, as well as under eccentric load, are carried out to investigate how the GFRP layer and the eccentricity affected the strain, the lateral deflection and the load capacity. The working feature, failure modes and the effect of GFRP tube confining are researched. The load-deflection curves and load-strain curves of the hybrid DSTCs under eccentric load are studied.(3) Introduce the cross-sectional shape coefficient and eccentricity influence coefficient, put forward the method to predict the FRP-concrete-steel double-skin square columns based on the ultimate beating capacities formulas of round GFRP tube filled with steel reinforced concrete under eccentric compression.