A total of twelve Cross-laminated Timber (CLT) shear walls and six ledgers were tested in the UNBC Wood Innovation and Research Laboratory in Prince George, BC.
Each shear wall consisted of two coupled panels: 7-ply, 191mm thick, 1219mm wide and 3658mm tall for an aspect ratio of 3:1. The panels were “balloon-framed” with a ledger attached a mid-height. Four different ledger configurations were tested: Type A – steel ledger attached with 16 screws distributed along the ledger length; Type B – steel ledger attached with 16 screws concentrated in the panel centres; Type C – steel ledger attached with a single pin in the panel centre; and Type D – glulam ledger attached with 16 screws distributed along the ledger length. Each ledger configuration was tested three times: once under quasi-static monotonic loading; and twice under quasi-static reversed cyclic loading. The load was applied in equal proportion at the top of the wall and at mid-height directly to the ledger. The horizontal, vertical and relative panel displacements were recorded with at twelve locations. For one shear wall with ledger types A, B and D, the ledger was subsequently tested under vertical quasi static monotonic loading to determine the ledgers’ remaining load-carrying capacity. For these latter tests, one ledger each was also tested without being subjected to any lateral loading.
The results demonstrated that the shear wall reached similar lateral load-carrying capacities under similar deflection for all four ledger types. Load-carrying capacity and accompanying deflection under reversed cyclic loading were reduced by values averaging around 20% with differences as a function of ledger type and loading direction. The vertical ledger tests showed that all three ledger types attached with 16 screws to the CLT panels had very similar load-carrying capacity and that the applied cyclic loading only led to small reductions in vertical capacity.