Analysis of concrete beams reinforced with auxetic and conventional honeycomb sandwich structures subject to close-in explosions

An urgent need for novel structures to enhance the blast resilience of reinforced concrete infrastructures has emerged in response to the increasing frequency of explosive events. This study presents, for the first time, an experimental perspective into the effectiveness of auxetic and conventional honeycomb sandwich (HS) beams in enhancing the blast resistance of reinforced concrete (RC) beams under close-in explosions. In the experiment, RC beams were reinforced with HS beams on the top side and subjected to close-in explosion conditions. The performance of these composite structures was compared to a control group of RC beams with homogenous steel plate reinforcements, lacking any additional protective measures. The findings reveal that incorporating auxetic HS beams substantially enhances the blast resistance of RC beams. This improvement is indicated by the significantly smaller midspan maximum displacements and less severe spalling of auxetic HS beams protected RC beams. To better understand the protective mechanisms of auxetic HS beams under blast loading, a validated finite element model was employed to analyze energy absorption characteristics, damage modes, and plastic deformation behavior under varying blast loads.