Experimental investigations on the blast response of reinforced NSC, FRC and UHPC I-shape girders under contact explosions

Abstract

To investigate the blast response and evaluate the structural resilience of reinforced I-shape girders, seven reinforced normal strength concrete (NSC), fiber reinforced concrete (FRC), and ultra-high performance concrete (UHPC) specimens are subjected to multiple contact explosions in this study. With the test results, the concrete damage regions and plastic deformation of steel bars are used to recognize the damage mechanism of the test specimens. The experimental results show that the damage modes of I-shape girders are mainly dominated by vertical punctures and transverse shear failures. Due to fragile characteristics, nearly 35 % of the punching crater in concrete webs, the entire shear failure of top plates, and severe plastic deformation of steel bars are discovered in NSC specimens. Polyethylene fibers improve ductility, allowing for smaller steel bar deflection and a reduction in punching depth to 21.6 % in FPC specimens. However, due to the oversized impact energies and the insufficient material strength, the transverse shear failure cannot be significantly mitigated. By contrast, not only significantly reduced punching depth but also greatly mitigated transverse shear failures are observed in UHPC specimens. Under 50 g∼200 g contact explosions, the punching depth ratios are reduced to 3.3 %, 16.6 %, and 25.8 %, merely. Apart from that, after explosions, the transverse shear failure and plastic deformation of steel bars can be effectively reduced. Due to the remarkably decreased damage regions, the UHPC specimens exhibit better structural resilience after blast loadings.