Tests of wall sheathing under realistic wind load

One of the keys to wind risk mitigation is to keep the building envelope intact as this keeps rain and water out and ensures that internal pressurization, with subsequent failures, does not happen. Typical failed components include roof and wall sheathing, vinyl siding, shingles, soffits, windows, garage doors, although major structural failures involving removal of roof trusses (at roof-to-wall, toe-nailed connections) also occur. The Three Little Pigs' Project test methodology involves accurate replication of the wind-induced surface pressures by the novel Pressure Loading Actuators (PLAs) and a (system of) airboxes. The PLAs provide highly realistic wind loading so that full-scale testing can now determine unambiguously the relationship between component strengths, design pressures, and wind speed. The current paper focuses on the implementation of the new test method to examine the performance of wall sheathing and nail pull-out. It was demonstrated that slowly increasing ramp loads can be interpreted as gust (peak) pressures, as failures under realistic dynamic traces occurred at about the same pressure as slowly increasing ramp loads. However, the "real" failures occurred in increments of a few mm for peak pressures of a magnitude greater than about -2.0 kPa. Therefore, it typically took many peaks to fail the sample, indicating that storm duration is a significant parameter in the failures as well. Considering Canadian design wind speeds, this form of construction was seen to be adequate in most major cities so that failure should only be observed rarely at design wind speeds.