Over the past three decades, fibre reinforced polymer (FRP) composites have steadily gained popularity in civil engineering applications due to their unique advantages. As a result of the considerable amount of research conducted on the behaviour of CFRP strengthened steelwork under static and fatigue loads, rehabilitation of steelwork using CFRP has increasingly been adopted in field applications. However, up to now, much uncertainty still exists on the dynamic performance and in particular the effects of loading rate on the behaviour of such members.
This paper is aimed at investigating the main differences between the responses of CFRP strengthened steel columns subject to various different loading rates. The basis of this study is an experimental program comprising a series of square hollow section (SHS) columns tested under two loading rates: quasi-static (0.05 mm/sec) and impact (4.43 mm/sec). CFRP was wrapped around the steel section in three different configurations including fibres oriented in the longitudinal direction, transverse direction and in both directions. The effect of co-existing axial compression applied prior and during the application of the transverse impact (or static) load was also examined. The axial load was introduced in the experimental program to simulate the normal service load that exists on columns in multi-storey frame buildings. Generally, it was found that the effectiveness of CFRP strengthening was increased at higher loading rates to different degrees depending on the CFRP configuration.