17SE05-DESTEFANO-Timber-Structural-WSF-170322

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Timber Frame Design
The Art of Engineering an
Exposed Structure
Disclaimer: This presentation was developed by a third party and is not funded by WoodWorks or the Softwood Lumber Board.
Jim DeStefano, P.E. AIA. F.SEI
“The Wood Products Council” is a 
Registered Provider with The 
American Institute of Architects 
Continuing Education Systems 
(AIA/CES), Provider #G516.
Credit(s) earned on completion of this 
course will be reported to AIA CES for 
AIA members. Certificates of 
Completion for both AIA members 
and non-AIA members are available 
upon request.
This course is registered with AIA CES
for continuing professional education. 
As such, it does not include content 
that may be deemed or construed to 
be an approval or endorsement by 
the AIA of any material of 
construction or any method or 
manner of handling, using, 
distributing, or dealing in any 
material or product.
______________________________
Questions related to specific materials, methods, 
and services will be addressed at the conclusion of 
this presentation.
Timber engineering is just as much an art as science, one 
that is rarely taught in college or part of a young 
engineer’s professional education. With this 
presentation, attendees have an opportunity to learn 
from a timber specialist involved in award winning 
timber-frame projects throughout the northeast. Topics 
will include the design of heavy timber trusses, glulam 
elements, joinery and connections, as well as exterior 
wall systems and designing for fire protection.
Course Description
Learning Objectives
• Apply the principles of timber truss 
design.
• Recognize options for timber-frame 
exterior wall systems.
• Consider basic joinery and 
connection methods and when to 
use them.
• Determine how to design timber 
frames for fire resistance.
Structural Engineering
The art of molding materials we do not 
wholly understand into shapes we cannot 
precisely analyze so as to withstand forces we 
cannot really assess in such a way that the 
community at large has no reason to suspect 
the extent of our ignorance
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.
Glulam Layup
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
778.0926.0
1365
BASEPEGV
GGF =
Mystic Seaport Welcome Center
Structural 
Insulated 
Panels (SIPs)
Design Guide for SIPs
ww.sips.org
Structural Behavior
• Deflections often control
• Shear deflection is significant
• Shear often controls strength
• Creep deflection is significant
Fire Resistance of 
Mass Timber
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
Keep Your Feet Dry
3D BIM
This concludes The American Institute 
of Architects Continuing Education 
Systems Course
QUESTIONS?
Jim DeStefano, P.E., AIA, F.SEI
jimd@dcstructural.com