Tensile shear strength of steel plate-reinforced larch timber as affected by further reinforcement of the wood with carbon fiber reinforced polymer (CFRP)

To improve the connecting strength of larch timbers, tensile shear test specimens were fabricated, and their connecting shear strength performance was examined. The control specimens consisted of larch timber reinforced with steel plate. These were compared with similar specimens in which the wood had been reinforced with carbon fiber reinforced polymer (CFRP). The reinforced specimens were fabricated in three types depending on the position of the CFRP reinforcement in the wooden part. All specimens were fabricated in two end distance types, depending on the bolt insertion position. The end distances examined were 60 mm (5D) and 84 mm (7D). The maximum connecting strength and the yield shear strength of each type were not different according to the CFRP reinforcement position. The reinforced specimens had an average connecting strength and yield shear strength that was 24% to 29% higher than the control specimens. The CFRP-reinforced specimens with an end distance of 5D had an average connecting strength and an average yield shear strength that that was 70% and 26% higher, respectively, than non-reinforced 7D specimens. The yield shear strength was predicted by measuring the bearing strengths of the larch timber samples and CFRP-reinforced timber samples. The predicted yield shear strength matched the measured yield shear strength.

Liquefaction analysis of Duncan Dam using strength ratios

B.C. Hydro performed extensive seismic safety studies for Duncan Dam in the late 1980s and early 1990s. The results of these studies indicated that Duncan Dam was reasonably safe from liquefaction-induced failure. A recently proposed liquefaction analysis procedure that uses strength ratios to assess liquefaction triggering and post-triggering stability was used to revisit the liquefaction analysis of Duncan Dam. When compared to the detailed field and analytical studies performed by B.C. Hydro, the proposed liquefaction analysis procedure predicts: (i) similar zones of liquefaction within a contractive unit of foundation sand; (ii) similar shear strengths at the triggering of liquefaction (yield shear strength) and at large strain (liquefied shear strength); and (iii) similar post-triggering factors of safety for slope stability. The good agreement suggests that the strength ratio based liquefaction analysis approach is relatively robust and is suitable for screening level studies for large projects or may serve as the primary analysis procedure for less complex projects.Key words: liquefaction, liquefied shear strength, yield shear strength, laboratory tests, penetration tests, Duncan Dam.