Combined Shear and Wind Uplift Resistance of Wood Structural Panel Shearwalls

Fracture Mechanics Models for Brittle Failure of Bottom Rails due to Uplift in Timber Frame Shear Walls

“…At what length will the crack start to grow vertically (if at all at any crack length)? The solution is given by taking (3) as it is and setting it equal to (14), in which = and ℎ = ℎ . These equations lead to the solution that the crack will start propagating in the vertical direction when = ℎ .…”

“…The material properties are those used in Serrano et al [19] and Caprolu et al [18]. Using (3) and (14), the point where the horizontal crack starts propagating vertically is = ℎ and is independent of the geometry and material properties of the bottom rail. The same exercise may be done using other models for the horizontal and vertical crack propagation, but an explicit expression can in general not be given for the point, where the horizontal crack starts propagating vertically.…”

“…All test specimens had bottom rails with ℎ = 45 mm and ℎ = 22.5 mm. Accordingly, (3) and (14) predict that the crack will change to propagating in the vertical direction after having propagated 22.5 mm horizontally. Though the measured figures given in Tables 4 and 5 are roughly in agreement with this prediction, the experimental results are too scarce and the variation is too large to make any firm conclusions about agreement between theory and experiments.…”

“…It should, however, be noted that (14) for the vertical crack propagation and (31) for the bending failure of the cantilever predict infinitely high failure loads for an initially horizontal crack = 0 ( = 0), and (3) and (32) will thus determine the failure load of the bottom rail for a horizontally propagating crack. For most practical applications, the shear failure will not be relevant either.…”

“…Duchateau [13] studied the uplift resistance of bottom rails in wood shear walls without holddowns in order to maintain bottom rail structural integrity. Yeh and Williamson [14] presented an experimental study on the combined shear and uplift resistance of wood structural panel shear walls. In the NAHB report [15], an experimental study is presented, where four types of partially anchored shear walls with varying nail size and spacing and with small round or big square washers were tested.…”