Circular concrete columns confined with GFRP tubes under repeated and sequential impact loads

Abstract

The experimental work conducted in this study aims to develop more understanding of the dynamic response of concrete-filled fiber reinforced polymer (FRP) tubes (CFFTs) columns under lateral impact load by testing 16 specimens. Three different types including reinforced concrete (RC), unreinforced CFFT and steel reinforced CFFT columns were tested. The specimens were tested under both repeated and sequential impact load testing protocols. Four parameters were investigated: the cross-section size, the thickness of the FRP tube, and the presence of longitudinal reinforcement. In addition, the effect of adding polypropylene fibers (PPF) to the concrete was also studied. Based on the experimental results, the damage mechanism, impact loads, deflections and strains were monitored and discussed. The results of this investigation confirmed that steel reinforced CFFT columns exhibited superior damage control characteristics when compared to RC columns. Increasing the thickness of the FRP tube decreased the displacement by up to 18 % and the residual displacement by up to 15 %. Adding PPF delayed the failure of the specimen and slightly enhanced its response. The experimental findings showed that longitudinal internal steel reinforcement played an important role in columns’ overall behavior and increased impact capacity.