GNGTS 2013 - Atti del 32° Convegno Nazionale

The maximum lateral resistance obtained from the subsequent monotonic test resulted equal to V max,M = 28.56 kN, and the collapse occurred due to the local cracking of a top joint ( V k = 14.4 kN, Eurocode 5). Globally, all the specimens showed high shear strength, large flexibility and dissipative capabilities under in-plane seismic loads. However, due to the different typologies of adopted carpentry joints (Figs. 1c, 1d, 1e), small differences in the global behavior of each shear wall were found. A first rough comparison between the analytically predicted strengths V k of each specimen and their experimental ultimate loads V max,M , for example, resulted in a ratio V k / V max,M respectively equal to 0.776 (S01), 0.708 (S02) and 0.505 (S03). If compared to the ratio f c,90,k / f c,90,mean = 0.7 typically considered for timber material, with f c,90,k and f c,90,mean the characteristic and average compressive strengths perpendicular to the grains of C24 spruce (UNI EN338:2009), collected data highlight the occurring of different failure mechanisms for each shear wall, and in particular the occurring of a local failure mechanism for specimen S03. Further calculations performed for specimens S01, S02, S03 (UNI EN 12512:2006) and based on collected cyclic test results highlighted also a dependency of the equivalent damping ratio n eq of each shear wall, respectively equal to 0.102, 0.190 and 0.173, on the adopted typology of carpentry joints. In any case, results of full-scale experiments demonstrated an overall good behavior of Blockhaus walls under seismic loads. Experimental prediction of the static friction coefficient. Further experimental tests were then performed on small Blockhaus components, in order to mechanically characterize the behavior of each component under the effects of a seismic event. Since the seismic response of Blockhaus shear walls under in-plane loads strongly depends on the interaction between multiple logs in contact, static friction experiments have been performed on small specimens. Fig. 2 – a) Horizontal in-plane load-lateral displacement curve for specimen S01 (cyclic and monotonic tests); b) specimen S02; c) specimen S03; d) detail of failure mechanism for specimens S01 and S02. 25 GNGTS 2013 S essione 2.1