Spalling in concrete arches subjected to shock wave and CFRP strengthening effect

The purpose of the present study is to put forward an innovative method to improve dynamic response behaviors of protective concrete arches subjected to blast load. To achieve this goal eight arches were made, of which six were strengthened with carbon fiber reinforced polymers (CFRPs) on the intrados. Field explosion experiments were designed and carried out to reveal the strengthening effects of different CFRP strengthening schemes. The dynamic structural responses of the tested arches were recorded through linear variable differential transformers (LVDTs) and pressure sensors. The results of the experiments, such as the distribution of concrete cracks and the debonding length of the CFRP strips, indicate that CFRPs are effective in reducing concrete cracking and spalling of the protective arches, and that the fully-bonding method is significantly more effective than the partially-bonding method. Meanwhile, when the scaled standoff distance decreases, the strengthened arches experience failures ranging from ductile cracking to dynamic spalling. Simplified analysis models are proposed to estimate the equivalent static load and to reveal the protective mechanism of the CFRP strengthening. The research confirms that by using the CFRP bonding technique, an efficiently protective concrete arch structure with excellent anti-explosion performance could be constructed.