The application of reinforced concrete (RC) beam with near-surface mounted (NSM) pre-stressed carbon fiber reinforced polymer (CFRP) plates has been increasingly widespread in civil engineering. However, debonding failure occurs easily in the early loading stage because of the prestress change at the end of CFRP plate. Therefore, it is important to find reliable, convenient and economical technical means to closely monitor the secure bonding between CFRP and concrete. In this paper, an active sensing approach for generating and sensing stress wave by embedded smart aggregates (SAs) is proposed, which provides a guarantee for the secure connection between CFRP and concrete. Two specimens with different non-pre-stressed bond lengths were fabricated in the laboratory. Six SAs were installed at different positions of the structure to monitor the degree of debonding damage during the loading process. The experiments showed that the optimal length of non-pre-stressed CFRP bond section (300 mm) can significantly improve the load characteristics and enhance the service performance of the structure. The theoretical analysis of wavelet packet shows that increasing the length of non-pre-stressed CFRP bond section can slow down the occurrence and propagation of debonding cracks. The debonding crack in the tension end region is earlier than that in the bond end region. The research results reflect that the developed approach can monitor the damage process caused by debonding cracks and provide early warning for the initial damage and the debonding failure.
This paper thoroughly investigates the performance and multi-parameter optimization of a dual-stage vibration isolation system with bio-inspired isolators (BI-DSVI) under different base excitations. The dynamic equations of the BI-DSVI are derived. Then, the optimization problem is defined, where three types of base excitation (translation and rotations around the two horizontal axes) are studied. The optimization results show that the vibration transmissibility can be greatly reduced (more than 30 dB) by multi-parameter optimization, and an optimal configuration of structural parameters exists for the bio-inspired isolators. The effective vibration isolation bandwidth is significantly widened. Finally, the paper thoroughly discusses the influence of the structural parameters of the bio-inspired isolators and the base excitation types on the vibration isolation performance. The parameter studies provide useful guidelines for the application of the bio-inspired isolator in dual-stage vibration isolation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.