Experimental Study on FRP-Strengthened Steel Tubular Members under Lateral Impact

Abstract

Hollow structural members are highly vulnerable structural components subjected to transverse impact loads. These tubular members have been used widely in both onshore and offshore structures where lateral impact forces can be expected from moving vehicles/vessels or terrorist attacks. Thus, strengthening of steel hollow tubular members is required to safely carry both service static and imposed dynamic impact loads. This paper presents the results from a series of tests on bare and fiber-reinforced polymer (FRP) strengthened circular hollow-section (CHS) steel members subjected to transverse impact loading at midspan. A total of 14 (2 bare and 12 strengthened) medium-scale specimens were tested to investigate the effect of FRP wrapping on the global and local deformation capacities of strengthened members under drop-hammer impact. Both carbon-fiber-reinforced polymer (CFRP) and glass-fiber-reinforced polymer (GFRP) sheets were used as strengthening materials. The results indicate that the FRP strengthening of the tubes enhances their impact-resistance capacity by reducing lateral displacements up to 29% compared to bare steel CHS specimens. The influence of FRP type, CFRP orientation, CFRP thickness, and effective bond length on the structural response and failure behavior of wrapped members were investigated. The results showed that the application of FRP in the longitudinal direction was effective to control the global deformations whereas the hoop layers were effective in reducing local inward deformations of CHS members.