Evaluation and identification of dynamic strain on a blast door subjected to blast loading using fibre Bragg grating sensors

Abstract

Tunnels and subway blast doors are effective barriers to terrorist attacks and emergencies, and research into the mechanical properties of blast doors under explosive dynamic loads can improve and enhance the performance thereof. In this article, surface strain measurements on subway blast door models under dynamic load are carried out using quasi-distributed fibre Bragg grating sensors. The principle underpinning fibre Bragg grating sensing is introduced before the experiment. In the experiment, a model of an explosion-proof door was designed, and the experimental foundation pit was designed to be used to fix the explosion-proof door. Then, eight fibre Bragg grating sensors are placed at different positions on the surface of the explosion door to measure the strain at the time of explosion. Through the experiment we found that the optical fibre grating sensing system can be used under explosive loading surface strain: the strain distribution on the surface of the protective door is revealed under large dynamic strain. At the same time, the rebound effect of the protective door in the explosion was found through the strain phenomenon in double peak phenomenon. The strain distribution and rebound effect in the test results can provide a useful reference for the mechanical design of the blasting door and the strain monitoring of reinforced concrete structures under dynamic load.