Influence of Weathering on the Structural Performance of Sheathing-to-Timber Connections

The sheathing-to-timber connection (STC) is a critical component of timber-framed shear walls. The STC provides the shear wall system with its racking resistance, while anchors and tiedowns provide resistance to sliding and overturning, respectively. Because building materials are exposed to weathering during construction, this study aims to quantify the influence of weathering on the structural performance of STCs. To achieve this aim, a total of 117 small-scale specimens were fabricated with 5 different sheathing types and 2 different timber species. Each specimen comprised 2 panels of sheathing connected to 2 short lengths of pine timber (90×35 mm cross-section), with a total of 16/2.8ϕ×30 mm (l) galvanised clouts at 45 mm spacings. Some specimens were tested under the EN 594 monotonic loading protocol and others were tested under the ISO 16670 cyclic loading protocol. Some specimens were exposed to the weather for a period of 6 months before being tested, while others were stored in an air-conditioned environment before being tested. The results show that weathering reduces the ultimate and yield capacity of STC connections by 3% and 5% on average, respectively; however, this result is not statistically significant for most sheathing types. The results varied, with some configurations having an ultimate capacity up to 16% higher and others having an ultimate capacity as much as 20% lower for weathered specimens compared to unweathered specimens. However, weathering reduces the stiffness of STCs by 61% and ductility by 50%, a statistically significant result. For most sheathing types, these findings do not support reductions to the design capacity of STCs that have been exposed to weathering.