Experimental-numerical investigation on the seismic behaviour of moment-resisting timber frames with densified veneer wood-reinforced timber joints and expanded tube fasteners

This paper investigates the seismic behaviour of moment-resisting timber frames with beam-column joints fastened with expanded tubes and reinforced with densified veneer wood. Laboratory experiments are carried out on single joints to investigate the cyclic behaviour and, more specifically, the impairment of strength, the ductility ratio and the equivalent viscous damping ratio. A phenomenological numerical model is proposed, where the beams and columns are schematized using linear-elastic beam elements, and the joints with non-linear hysteretic spring calibrated on the results of the experimental tests. The model is used to analyse some representative moment-transmitting structures characterised by different number of bays and storeys. After an estimation of the lateral load-carrying capacity using a pushover analysis, the numerical model is used to estimate the behaviour factor. An incremental dynamic analysis is performed using a set of accelerograms spectrum consistent with a chosen design spectrum. The analyses lead to an estimation of the behaviour factor of 3 and 6 for a portal frame and a five-storey, three-bay frame, respectively, which confirms the highly dissipative behaviour of this kind of moment connection.