1996 LRFD Manual for Engineered Wood Construction

GUIDELINELRFD MANUALTO LRFDFORFORENGINEEREDSTRUCTURALWOODCOMPOSITECONSTRUCTIONLUMBER 1717were higher than required by the UBC. Roof live loadwas 25 psf, governed by snow loading. Roof dead loadwas 10 psf.Materials SpecificationsThe materials list for this panelized wood roof systemis rather simple. 24F glulam girders and purlins wereused. Sub-purlins were No. 1&Btr. Douglas Fir - Larch2x4s and the panels were 1/2 in. Rated Sheathing OSB.Simpson metal hangers were used to connect purlins togirders and sub-purlins to purlins. For OSB connectionsto the perimeter walls 16d nails were used. For other panelnailing, 8d nails were used. R-11 ceiling insulation wasinstalled. All materials were readily available at localbuilding supply dealers with the exception of the 8x8-footOSB which was special ordered from the factory througha local building materials supplier.The roofing was a hot mop asphalt and the exteriorwalls of the buildings were painted.Construction ProcessThe engineering firm for this project has been involvedin the design of over 40 million square feet of panelizedwood roof systems. The reason for the proliferation ofthis system has simply been its erection speed, efficiency,and availability of materials.Reinforced concrete walls, twenty-eight feet long,were poured on the ground and tilted into position. Theconcrete formwork utilized a double 2x4 lumber framewhich became the top plate of the wall. Steel columns,placed in a 25x50-foot grid, were connected with glulambeams to form the primary structural network. Split-lamconnections were used wherever glulam beam sizechanged.The 8x25-foot “panels” were fabricated on the groundby a two man crew. The unique feature of this panel systemwas the use of 8' x 8' OSB (Oriented Strand Board)structural panels. The OSB was nailed with its strongaxis aligned parallel to the 2x4 sub-purlins spaced twofeet on center. Because of the panel orientation with thesub-purlins, a 1/2 in. thick, Rated Sheathing grade of OSBwas required. With the OSB nailed to the 25-foot glulampurlin and sub-purlins, the assembly was ready to be liftedinto position.2PROJECT PROFILES: CASE STUDIESAMERICAN FOREST & PAPER ASSOCIATION