Alexander Rosenthal Design Project 2 Arch 562: Structural Design, Winter 2011 Stephen Duff, Mark Donofrio, Nate Poel
Design and Analysis of a Timber Truss for a 30’ x 50’ Meeting Hall
model photograph
Introduction: The 30’ x 50’ meeting hall is crowned by six heavy timber trusses, supported by two 50’ masonry bearing walls that run longitudinally on each side of the hall. The walls are 15’ tall, and are penetrated by five square openings, centered in each bay of the structure. The shape of the trusses implies a volume of space that is loosely subdivided into a large middle zone and two smaller zones at the long edges of the hall. The top chord of the truss is raised 4’ above the masonry bearing wall, creating space for clerestory windows that bring generous amounts of natural light into the meeting hall. The trusses are joined by 4”x6” #1 Douglas Fir purlins, spaced 30” on center and covered by 2” nominal Douglas Fir tongue and groove boards. Above is 5/8” structural plywood sheathing (providing lateral bracing in the roof plane), rigid insulation, a second layer of 5/8” sheathing, 15# felt and cedar shingles. The members of the truss are joined by a 1/2” steel knife plate, centered in each member, and secured with bolts.