Close-range blast behavior of hybrid FRP-concrete-steel double-skin tubular member

This research experimentally and numerically investigates the dynamic response of hybrid fiber reinforced polymer (FRP)-concrete-steel double-skin tubular member (DSTM) under close-range blast load. Three DSTMs, 2500 mm in length and 200 mm in diameter, were designed and tested under close-range blast load at a scaled distance of 0.251 m/kg1/3. The blast pressure-time histories, damage modes and deflection characteristics of blasted DSTMs were acquired and analyzed. The test results demonstrate that the DSTMs exhibit highly localized damage mode (FRP tube ruptures and concrete fragmentations) under close-range blast load. Partial concrete filling into steel tube and adding steel ribs can both improve the blast resistant capacity of DSTM, with the effect of steel ribs more pronounced. Afterwards, refined numerical models were established, and the models' accuracies were validated using the current test data. The validated models were used to reveal the blast resistant mechanism of DSTM, including the damage evolution, energy absorption mechanism, and confinement/protective effect from FRP tube. Furthermore, parametric analyses were conducted to study the effects of blast scaled distance, void ratio, and steel rib configurations on the close-range blast behavior of DSTM.