EXPERIMENTAL RESEARCH ON SLENDER CIRCULAR TUBULAR STEEL BRACES STRENGTHENED BY CARBON FIBER REINFORCED POLYMER

摘要

Although the application of carbon fiber reinforced polymers (CFRP) on strengthening of concrete structures has been reported widely due to its superior mechanical and physical properties: high strength-to-weight ratio, corrosion resistance, easy application and construction, there are relatively few applications to steel structures, especially to tubular steel structures. This paper firstly reviews previous and on-going filed projects, experimental and theoretical researches on retrofitting of tubular steel structures by CFRP. In order to investigate the performance of circular tubular steel braces retrofitted with CFRP, five long circular steel braces (88.9 mmX 4 mm) wrapped with different longitudinal CFRP sheets, compared with two control specimens without CFRP retrofitting, are tested to study the effects of CFRP on overall buckling behavior. In all CFRP-retrofitted braces, axial compression and lateral deflections are reduced. The experimental findings show that externally bonded longitudinal CFRP sheets are effective in increasing the axial strength and stiffness of slender braces. For the specimen tested, depending on the number of CFRP sheet layer, the percentage increase in strength ranged from 26.33% to 84.03%. A linear relationship between the axial compression load and the number of CFRP sheet layers is developed based on the test results at the same time. The possibility of the application of CFRP on strengthening steel structures in offshore engineering is also discussed in this paper.