We recently read a very informative article on bowstring trusses that was published in the February issue of Structural Engineers Association of Washington (SEAW) Seattle Chapter Newsletter – "Equilibrium."

The article was written by Paul Gilham, P.E., and Terry McKee, P.E., both from Western Wood Structures. The authors discuss the performance of timber bowstring trusses, which have been used for many years in commercial and industrial applications. A significant issue related to these trusses is that several factors have led to the trusses being overstressed by today’s code requirements.

In fact, in some cases, these trusses have been rendered as "dangerous members." This article gives a very good history of the issues and provides some concepts on retrofitting techniques to meet current code requirements. The authors have graciously provided us with a reprint of the article, which can be accessed here.