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Laminated timber-concrete (LTC) and steel-timber-concrete composite beam (S-LTC) members with adhesive interlayer connections were experimentally investigated. This paper presents the results of the acoustic emission (AE) investigation performed during short-term static ramp-loading to failure tests. The beam specimens were continuously monitored using accelerometers connected to a four channel dynamic signal analyzer. For LTC beams, the failure of the timber in tension was typically observed; therefore, a steel layer was added to the tension side of the timber layer to increase the strength and to induce a ductile behaviour. The results of the AE investigations on two LTC and two S-LTC specimens reveal the progression of the failure as it initiates and gradually develops within the beams, leading to the tension failure and shear failure modes for the LTC and S-LTC specimens, respectively. The results confirm that the fast Fourier transformation (FFT) and waterfall type of spectral analysis have an important role in supplying substantial and reliable amounts of information for the identification of different phenomena in connection with the failure process of the investigated structural members.
Acoustic emissions, Adhesive connection, Laminated structural members, Timber-concrete composite beams, Waterfall spectral analysis
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