Timber-Frame Design: the Art of Exposed Structure
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Timber Frame Design The Art of Exposed Structure Jim DeStefano, P.E. AIA. F.SEI Disclaimer: This presentation was developed by a third party and is not funded by WoodWorks or the Softwood Lumber Board. “The Wood Products Council” is a This course is registered with AIA CES Registered Provider with The for continuing professional education. American Institute of Architects As such, it does not include content Continuing Education Systems that may be deemed or construed to (AIA/CES), Provider #G516. be an approval or endorsement by the AIA of any material of Credit(s) earned on completion of this construction or any method or course will be reported to AIA CES for manner of handling, using, AIA members. Certificates of distributing, or dealing in any Completion for both AIA members material or product. and non-AIA members are available upon request. ______________________________ Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation. Course Description There is something inherently spectacular about the look and feel of exposed timber. It’s more than a structural system. It’s a natural at creating architectural drama— and is often the most practical, cost effective, and sustainable choice for achieving that objective. This entertaining and informative presentation will demonstrate how timber has been used to great effect on a variety of projects. Emphasizing the need for form to follow function, it will cover traditional vs. contemporary design approaches, how to select the right species and construction type, and available timber systems. Learning Objectives • Discuss the evolution of timber frame buildings with defining features drawn from both traditional and contemporary timber design, and apply the principals of form following function through project examples. • Explore architectural design considerations such as species, construction types, products, and finishes. • Identify the appropriate wood structural system for specific applications such as trusses, glulam elements, mass timber, and exterior walls, while becoming familiar with connection options and fire-resistive design requirements. • Study the cost and schedule variables associated with delivering a timber frame project in the Southeastern U.S. Modern Architecture – Form Follows Function Post Modernism – Structure is Irrelevant Timber Form in Architecture Mass Timber Mass Timber is not a New Idea Traditional American Mill Buildings Church of the Holy Spirit Timber Frame Revival Saint Patrick Church Winchendon School Rockport Concert Hall Beaverton Public Library Material Selection Timber Species Douglas Fir White Pine Southern Pine Red Oak White Oak Alaska Yellow Cedar Douglas Fir #1 Eastern White Pine #2 Red Oak #2 White Oak #2 Southern Yellow Pine #2 Alaska Yellow Cedar #1 Naturally decay and termite resistant Radio Frequency Kiln Drying FraserWood Glulam Timbers • Douglas Fir • Southern Pine Glulam Layup Hotchkiss Biomass Plant Parallam - PSL Timbers in the Round Antique Timber Recycled – Re-sawn Industrial Timbers Forest Salvage - Standing Dead Wood o Pine Bark Beetle o Emerald Ash Borer o Woolly Adelgid Reclaimed – River Salvage Sustainability What is Green about Timber? • Carbon Sequestration • Low embodied energy • Bio based • Renewable • Natural Carbon Sequestration For every pound of wood grown, 1.47 pounds of carbon dioxide is extracted from the atmosphere and replaced with 1.07 pounds of oxygen Sustainable Forestry Clear Cut Even Age Forestry Sustainable Timber Harvest • Wildlife Habitat • Riparian Fringe • Old Growth Stands • Biodiversity • Regeneration Timber Fabrication & Erection Finding a Professional www.tfguild.org Schedule Lead Time – Mill Order, Shop Drawings, Fabrication Erection - Fast Shop Fabrication CNC Fabrication Frame Erection Topping Out 3D BIM Delegated Design Responsibility Structural Engineer of Record (SER) vs Specialty Structural Engineer (SSE) Structural Engineer of Record – responsible for the entire structural frame and foundation Specialty Structural Engineer – responsible for the timber frame only Mystic Seaport Mystic Seaport Lamination Shop Building Code Issues International Building Code Construction Types Type I – non-combustible Type II – non-combustible Type III – combustible framing non-combustible exterior walls Type IV – heavy timber Type V – wood construction Type IV Heavy Timber Construction Exterior walls non-combustible No concealed spaces Columns 8x8 supporting floor & roof; 6x8 supporting roof only Floor beams 6x10 minimum Roof beams 4x6 minimum Flooring 1” T&G over 3” T&G with material laid so as to not have continuous joints Roof deck 2” T&G – SIPs not permitted Portland Jetport Haystack Mountain Base Lodge SIP Enclosure Equestrian Buildings Wellington, FL Salt Shed Design Considerations Chamfers and Carvings Surface Treatment Planed and Oiled Rough Sawn Hewn Adzed Color Contrast Lighten Up Cross Laminated Timber - CLT What is CLT? Solid wood panel 3 layers min. of solid sawn lams 90 deg. cross-lams Similar to plywood sheathing Common CLT layups 3-ply 3-layer 5-ply 5-layer 7-ply 7-layer CLTs Curvilinear Forms CLT Art Timber & CLT Cost That all depends – budget $25 to $55 per SF Nail Laminated Timber - NLT Building for Hurricane Survival Wind Wind Damage – avoidable with engineering CLT Shearwalls Blast Testing of CLTs Forest Products Laboratory CLT Safe Room Tests Timber Engineering New Canaan Library circa 1977 Saint Joseph Church circa 1987 Saint Patrick Church circa 2007 Hammer Beam Truss Joinery Howe Truss Fink Truss Scissor Truss Hammer Beam Truss Hammer Beam Truss Westminster Hall Cruck Frame The Lodge at Crooked Lake Siren, WI The Depot Kent, CT 3 Simple Rules for engineering of timber joints Rule #1 The geometry of the joint should have mating surfaces that allow all structural loads to be transferred in bearing of one member against the other. Truss Heel Joint Truss King Post Joint Rule #2 The wood removed to create the joint should not unduly weaken the member. Rule #3 Allow for dimension changes due to seasoning of timber. The geometry of the joint should not be altered by shrinkage of the wood and bearing surfaces should remain in tight contact. Timber Rivets NDS • Timber Sizing • Bolted Connections • Timber Rivets www.timberframeengineeringcouncil.org Double Shear in Peg = .0 926 .0 778 FV 1365 GPEG GBASE Mystic Seaport Design for Fire Fire Resistance of Mass Timber Comparative Fire Test Source: Aitc AWC -Technical Report 10 www.awc.org Effective Char Layer Thickness 1 hour 1.8” 1 ½ hour 2.5” 2 hour 3.2” Mass Timber Fire Performance • Collapse proceeded by loud cracking and hissing noise • Collapse proceeded by large deflections • Steel plate and bolt connections fail suddenly Protect Steel Hardware Design for Durability Decay and Termite Resistant Timber 1. Preservative treatment - CCA, ACQ, Penta, Borate 2. Naturally resistant species – Alaska Yellow Cedar Design for Durability Keep Your Feet Dry Spruce Peak Stowe, VT QUESTIONS? This concludes The American Institute of Architects Continuing Education Systems Course Jim DeStefano, P.E., AIA, F.SEI [email protected].