Mechanical characteristics of bridge columns strengthened with fiber-reinforced polymer under two-stage loading

Based on studying the mechanical characteristics of bridge columns strengthened with fiber-reinforced polymer (FRP) under the single-stage loading and two-stage loading, the computational methods of axial compressive strength of the columns strengthened with FRP are analyzed with the strength reduction theorem. Discussions are presented on the relationships between initial loading and axial compressive strength of columns strengthened with FRP, and compare the above two calculations with the results gotten by the method of the Specifications for Strengthening Design of Highway Bridges(JTG/T J22-2008). The results indicate that the axial compressive strength under two-stage loading is lower than one under single-stage loading, and as the initial load increases, the compressive strength becomes smaller. It is useless when the initial loads are considerable.