Heavy snow accumulations on the roof of an elementary school in central Oregon in January 2017 caused structural damage to six wood roof trusses that span approximately 75 feet. The trusses were found to have some bolted connection failures at heel plates, as well as three split and fractured web elements also associated with their bolted connections. Snow load on the roof was reportedly around 40 pounds per square foot (psf), while the trusses were initially designed for 30 psf. …
Author Archives : Zeno Martin, P.E., S.E.
Zeno Martin, P.E., S.E., is an Associate Principal at Wiss, Janney, Elstner Associates, Inc., Seattle, WA. He can be reached at zmartin@wje.com.
Condensation on interior surfaces can cause corrosion and wood decay if not addressed promptly. Repair and restoration of decayed structural elements are important. Equally important is determining the source of the problem, so it does not reoccur. Condensation is moisture vapor collecting on a cold surface – in this case, wood roof sheathing at the interior of the building. …
Are Upgrades Required?
When done rationally, maintaining and repairing existing buildings represents an efficient use of resources that should be promoted. Also, reusing and repairing existing construction becomes increasingly important as sustainability becomes a higher priority (SEI 2013). …
There is an important design consideration for wood floor framing that is not likely to be found in building codes or design standards – differential deflection. This issue is often overlooked, but can lead to significant performance problems. Differential deflection, as described here, is the change in elevation from one framing member to the adjacent member. Differential deflection may escape consideration. Building code requirements and design standards for deflection typically pertain only to the deflection along the span length of an individual member. Problems related to differential deflection can arise when one long span member deflects in flexure, within building code limits, while the adjacent member does not, often due to different support conditions or stiffness (Figure 1). …