Structural Design of Mass Timber Framing Systems

structural design of mass timber framing systems

Bay Area Ian Boyle, P.E., S.E., P.Eng., Struct.Eng. November 7, design symposium fast +epp 2018 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 Registered Provider with The CES for continuing professional American Institute of Architects education. As such, it does not Continuing Education Systems include content that may be (AIA/CES), Provider #G516. deemed or construed to be an approval or endorsement by the AIA of any material of construction Credit(s) earned on completion of this course will be reported to AIA or any method or manner of handling, using, distributing, or CES for AIA members. Certificates of Completion for both AIA dealing in any material or product. members and non-AIA members are available upon request. Mass timber structural framing systems have high strength-to-weight ratios, are dimensionally stable, and are quickly becoming systems of choice for sustainably minded designers. This presentation will provide a detailed look at the structural design processes associated with a variety of mass timber products, including glued-laminated timber (glulam), cross-laminated timber (CLT), and nail- laminated timber (NLT). Applications for the use of these products in gravity force-resisting systems under modern building codes will be discussed. Other technical topics will include use of mass timber panels as two-way spanning slabs, connection options and design considerations, and detailing and construction best practices.

course description At the end of this course, participants will be able to:

1. Discuss mass timber products and building systems and their possibilities as structural framing. 2. Compare structural properties and performance characteristics of mass timber products and review their unique design considerations. 3. Review structural design steps for members and connections in common mass timber framing systems. 4. Highlight structural detailing best practices to address items such as shrinkage and expansion, load path continuity, and speed of construction.

3 connections overview gravity framing

nail-laminated timber structural composite lumber (LSL, LVL) (NLT)

cross-laminated timber (CLT)

glulam panels (GLT) wood-concrete composites

plank decks decking gravity framing 2x “joists” at 38mm (1-1/2”)

choose: depth, profile species, grade continuous vs. butt-jointed laminations

NLT design gravity framing detail for shrinkage and swelling

NLT design gravity framing

design guide thinkwood.com

NLT design gravity framing “beam on the flat”

A A A A A A A A A A A

GLT design gravity framing detail for shrinkage and swelling

GLT design gravity framing dimensional stability APA PRG 320 defines structural grades panel sizes vary by supplier cross laminations reduce strength and stiffness in primary span direction

CLT design gravity framing 2-way span capability

CLT design CLT design gravity framing design guide thinkwood.com

CLT design gravity framing

NLT may be most appropriate if: floor structure spans one way floor structure is curved in one direction budget is tight structure is an addition or alteration to an existing building (no crane access from above) a less “manufactured” aesthetic is desired

decisions decisions... gravity framing

GLT may be most appropriate if: floor structure spans one way spans are long (no strength/stiffness reduction as for NLT with butt joints) a clean aesthetic is desired

decisions decisions... gravity framing

CLT may be most appropriate if: floor structure needs to span in two directions (e.g. weak-axis cantilevers) a clean aesthetic is desired accommodating shrinkage and swelling during construction is difficult tight tolerances are required

decisions decisions... gravity framing

2x4 NLT, 3” GLT, 3-ply CLT (4” ±) ≤ 12’ ≤ approx. L/40

2x6 NLT, 5” GLT, 5-ply CLT (7” ±) 10’ – 17’ approx. L/20 to L/40 typical spans gravity framing

2x8 NLT, 7” GLT 14’ – 21’ approx. L/24 to L/36

2x10 NLT, 8 1/2” GLT, 7-ply CLT (10” ±) 17’ – 24’ approx. L/22 to L/34 typical spans gravity framing

2x12 NLT, 9-ply CLT (12” ±) 20’ – 26’ approx. L/20 to L/28

typical spans gravity framing deflections include creep ponding effects for concrete toppings?

vibrations when in doubt, calculate accelerations! damping values? AISC Design Guide 11 (2nd Edition) CSA O86 Annex A NBC 2015 Structural Commentary D ISO 10137 serviceability gravity 1 framing lateral 2 systems

3 connections overview lateral systems

shear walls

Photo Credit: Sissi Slotover-Smutny vertical LFRS lateral systems

rocking walls

Illustration Credit: PresLam vertical LFRS rocking moment frames Photo Credit: Equilibrium Consulting wood braced frames

vertical hybrids LFRS (steel or concrete LFRS) lateral systems

wood, steel, or concrete? walls or frames?

code approvals building height and lateral load demands designing for resilience? architectural and planning considerations

decisions decisions... diaphragms lateral systems

diaphragms lateral systems

white paper Breneman et al, “An Approach to CLT Diaphragm Modeling for Seismic Design with Application to a U.S. High-Rise Project”

design example Structurlam et al, “CLT Horizontal Diaphragm Design Example”

CLT diaphragm design aids gravity 1 framing lateral 2 systems

3 connections overview the devil is in the details what’s your philosophy? connections Photo Credit: Reiulf Ramstad Arkitekter connections in concrete Photo Credit: Cast Connex

connections in Photo Credit: Ben McMillan steel connections in steel connections in stick frame Photo Credits: Fire Tower Engineered Timber connections in timber frame Photo Credit: TimberPlates.com

Photo Credit: VicBeam Photo Credit: Uihlein-Wilson Architects connections in hybrids and mass timber? Photo Credits: Shigeru Ban Architects connections in hybrids and mass timber? connections make it buildable make it beautiful …and don’t forget about mother nature what’s your philosophy ? tallwood house at brock commons

column connection tallwood house at brock commons

column connection Photo Credit: Seagate Structures column connection tallwood house at brock commons

column connection tallwood house at brock commons 2

1.5

1 Deflection (in) Deflection 0.5

0 Dead Load Elastic Live Load Elastic Longitudinal Creep and Joint Total Shrinkage Settlement column connection tallwood house at brock commons

column connection tallwood house at brock commons

column connection column connection mec head office

a - a Photo Credit: DGS Construction beam saddle mec head office

Photo Credit: DGS Construction beam saddle wilson school of design

Photo Credit: DGS Construction tight-fit pin shear connection a - a wilson school of design

tight-fit pin shear connection wilson school of design

tight-fit pin shear connection ubc bus shelters

Photo Credit: PUBLIC self-tapping screws ubc bus shelters

Photo Credit: SFS Intec self-tapping screws ubc bus shelters

self-tapping screws ubc bus shelters

self-tapping screws whistler gateway loop

HSK plate moment connection whistler gateway loop

Photo Credit: TiComTec

HSK plate moment connection whistler gateway loop

HSK plate moment connection grandview heights aquatic centre

Photo Credits: Ema Peter tension splice grandview heights aquatic centre

PLAN VIEW tension splice grandview heights aquatic centre

tension splice grandview heights aquatic centre

tension splice arena stage performing arts center

Photo Credit: Nic Lehoux steel casting arena stage performing arts center

Image Credits: StructureCraft Builders

steel casting richmond olympic oval

shrinkage crack reinforcement richmond olympic oval a

a - a shrinkage crack reinforcement richmond olympic oval

shrinkage crack reinforcement first principles

it’s not rocket science, but…

you’re not just a structural engineer anymore

in closing This concludes the American Institute of Architects Continuing Education Systems Course

[email protected] www.fastepp.com thank you