Real-time assessment of timber-surface crack repair is crucial to the stability and safety of timber structures. Epoxy resin was used to repair timber cracks, and the active sensing technique using piezoelectric ceramics was applied to monitor the repair process of timber surface cracks in real time. Sixteen wood samples were designed for axial compression tests and active monitoring tests. A pair of lead zirconate titanate patches was pasted on the surface of the timber specimens as actuators and sensors for signal transmission and reception, through wavelet packet analysis, the variations in the signal amplitude, and wavelet coefficients. The relationship between the wavelet packet energy of the monitoring signal and the ultimate bearing capacity of the specimens at different periods after grouting was established. Based on the root-mean-square deviation, the damage index, DI, was introduced to evaluate the repair degree of timber surface cracks quantitatively. The results showed that the active sensing method can evaluate the strength development in timber-surface crack repair in real time.
In traditional Chinese wooden structural buildings, mortise-tenon joints are used as connection nodes. Under the erosion effects from wind and rain, such nodes are prone to aging and loosening. If theyare not tracked and repaired in time, they are likely to cause structural damage when they encounter sudden loads such as earthquakes. In accordance with engineering practice, one mortise-tenon joint specimen with a penetrating straight tenon and one mortise-tenon joint specimen without a penetrating tenon were constructed. Active sensing technology based on piezoelectric ceramics was used to identify the loosening state of tenon and mortise joints. The amplitude of the piezoelectric signal, wavelet packet energy, information entropy, and damage index based on the root mean square deviation were analyzed. It was found that with the increase in loosening damage, the amplitude of the signal gradually decreases, and the information entropy gradually increases. When the damage reaches a certain extent, the changes in the monitoring signal characteristics is limited. The proposed monitoring method can be used to identify the damage state for mortise-tenon joints effectively, and the research results can provide a valuable guideline for the repair of mortise-tenon joints used in traditional wooden structures.
To address the problem that carbon fibre reinforced polymer (CFRP) composite material is not easy to directly measure the bond strength of the CFRP-timber column interface during the process of strengthening timber column, a real-time monitoring method of CFRP-timber interface bond strength based on piezoelectric ceramic active sensing is proposed to determine the interface bond strength directly from the structural response signal.. A total of 15 specimens were designed for the active monitoring test and tensile test, and the monitoring signals at different enhancement times were compared and analyzed using wavelet packets, power spectral density, and short-time Fourier transform, and it was found that the amplitude and power spectral density of the signals increased as the reinforcement time increased. The mapping relationship between wavelet packet energy and bond strength is obtained, providing a more efficient and robust way of monitoring the bond strength between CFRP and timber columns during reinforcement.
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.