Study On The Axial Compression And Hysteretic Behavior Of Steel-gfrp-seasand Concrete Columns Based On Unified Theory

With the rapid development of infrastructure, river sand supply shortage has become increasingly prominent while the sea sand storage is rich. The mechanical properties of sea sand is almost the same with river sand, but the chloride ion contained in sea sand causes corrosion of steel and will seriously affect the durability of components. This paper presents a new kind of composite component which can apply sea-sand safely and reasonably. Specifically practice is lay FRP pipe or FRP sheet between steel pipe and the inner concrete. FRP material is widely used in structural field since its high strength and good corrosion resistance. The new form of composite structure proposed in this article can alleviate the status of river sand shortage. The research is of important social and practical significance.This paper mainly studied on the axial bearing capacity and seismic performance of steel-GFRP-concrete structure. Firstly is an axial compression experiment on a group of typical specimen. Following is parameters study using finite element analysis software ABAQUS. Ultimate strength is obtained with the variation of the related parameters. And then deduced the ultimate bearing capacity formula based on the unified theory of concrete-filled steel tubes. Since the brittle feature of FRP material, the hysteretic behavior of the proposed structure under fixed axial force and cyclic horizontal load is studied based on FEA software ABAQUS. The variation law of the skeleton curve is obtained with the related parameters. And then revised the existing restoring force model of solid and hollow CFST to satisfy the proposed component, and deduced the simplified formula of ductility factor. Finally this paper proposed two new methods of applying sea-sand in CFST. Main conclusions of this paper are as follows:(1) FRP tube can increase the ultimate bearing capacity of the CFST, and the axial bearing capacity formula is obtained.(2) FRP tube can reduce the ductility of the component; the skeleton curve will change suddenly when FRP fractures. However, the ductility efficient still meets the requirements in most cases.(3) For CFST components, laid a FRP panel or centrifugally cast an ordinary concrete layer can isolate the corrosion of chloride ion to the steel tube.