Axial Compression Test Of GFRP-Recycled Concrete-Steel Double-Skin Tubular Long Columns

In recent years, Fiber Reinforced Polymer(shorten as FRP) is widely focused by researches because of its superior material properties such as high strength, corrosion resistance etc. Prof.Teng, has recently proposed Hybrid FRP-Concrete-Steel Double-Skin tubular Columns(DSTCs) which is a new form of hybrid columns. The new column consists of an outer tube made of Fiber-Reinforced Polymer(FRP) and an inner tube made of steel, with the space between filled with concrete. In this new hybrid column, the three constituent materials are optimally combined to achieve several advantages not available with existing columns. At the same time, because of the construction waste is increasing, it is an important measure to solve harmonious development of concrete aggregate and ecological environment through utilizing abandoned concrete to process the recycled aggregate to make use in the view of sustainable development. In this paper, recycled concrete was used to replace normal concrete materials in DSTCs, so that it can effectively improve the use value of the recycled concrete. This paper aims at the experimental study on the ultimate capacity of GFRP-recycled concrete-steel double-skin tubular long columns under axial compression.Firstly, the production process of the columns is elaborated as well as the mechanical tests on the GFRP tube, seamless steel pipe and recycled concrete. Next, experimental research on the GFRP-recycled concrete-steel double-skin tubular columns under axial ly loaded are carried out to investigate the mechanical properties of working feature. The influence of the principal factors, such as slenderness ratio、replacement rate of recycled coarse aggregate and the loading methods, on the ultimate capacity and ductility of specimens is researched. The load-mid-height lateral deflection curves of specimens-. load-axial strain curves of GFRP tubes and load-axial strain curves of steel tubes under axial compression is also studied.Finally, existing method on the capacity of FRP-concrete-steel double-skin long columns subjected to axial load is use to predict the ultimate bearing capacity. Different method is used to predict the ultimate bearing capacity of specimens under different laoding method. The method on the capacity of concrete double-skin columns is suitable for predict the ultimate bearing capacity of recycled concrete double-skin columns. The results are reasonably close agreement with the test datum.