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Midply Shearwalls: High Capacity
Shearwalls for Midrise Wood
Frame Construction
Vancouver
October 30, 2014
Marjan Popovski, Ph.D., P.Eng.
Principal Scientist and Quality Manager
Advanced Building Systems Department
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Copyright Materials
This presentation is protected by US and International
Copyright laws. Reproduction, distribution, display and
use of the presentation without written permission of
the speaker is prohibited
© FPInnovations 2014
2
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Program Education Credit Information
Canadian Wood Council, Wood WORKS! and the Wood Solutions Fair is a
Registered Provider with The American Institute of Architects Continuing
Education System; the Architectural Institute of British Columbia and the
Engineering Institute of Canada. Credit earned on completion of this program will
be reported on behalf of members of each CES provider for those who complete
a participation form at the registration counter. Certificates of Completion for non-
AIA, AIBC or EIC members are available on request.
This program is registered with the 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.
3
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Learning Outcomes
At the end of this program, participants will be
able to:
• Understand the basics of Midply shearwalls
• Recognize the advantages of using Midply shearwalls
• Get familiar with the performance of Midply shearwalls
based on conducted testing
• Calculate the resistance and create construction details
for Midply shearwalls
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FPInnovations: Canada’s Forest
Research Institute
A Canadian Public-Private Partnership
▫ Federal Government
▫ Provinces & Territories
▫ Industry Members
500 Employees
3 main locations
Budget $95 million
5
Research: Sustainable Forestry Sustainable Building Systems
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Presentation Outline
Midrise Wood Frame Construction
Concept of Midply Walls
Background and Research Information
Design Approach
Construction Details
Application Examples
Conclusions
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Start of Mid-Rise Wood-Frame
Construction in BC
Limit raised to 6 storeys in BC effective April 2009
Intensive input from leading experts in the field (including FPI
staff) along with stakeholders from the residential building
industry
APEG BC developed
Technical & Practice Bulletin for
mid-rise wood-frame buildings
72 buildings constructed or
underway and 129
in design phase
7
Photo Courtesy of WoodWorks!
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Midrise Construction in BC
8
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Midrise Wood Frame Construction in
Rest of Canada
April 2013: Régie du Bâtiment du Québec (RBQ) permitted use of wood-frame construction up to 6 storeys
Ontario Building Code revised to allow wood-frame construction up to 6 storeys as of January 2015
5- and 6-storey wood-frame construction approved by all committees for in 2015 NBCC waiting final decision of the Commission
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Midrise Wood Frame Construction
Handbook
With support from NRCan working on a Handbook for
Midrise Wood Frame Construction
Expected in early 2015
▫ Structural Products, Components and Assemblies
▫ Fire Safety Design
▫ Structural Design
▫ Floor Vibration Control
▫ Design for Vertical Differential Movement
▫ Noise Control
▫ Durable and Efficient Building Enclosure
▫ Design for Elevator Shafts and Stairwells
▫ Prefabricated Systems
10
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Midrise Construction in the US
Already Code Approved in the US
Adoption varies by regions and jurisdictions
11
Photo: BC WoodWorks!
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5-7 Storey Apartments in the US
12
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Regular vs Midply Shearwall
38 89 mm lumber stud spaced at 406 mm o.c.
1.22 2.44 m wood-based panel
Sheathing fastened to the narrow face of framing members
38 89 mm studs rotated 90 degrees (on flat) 610mm o.c.
1.22 2.44 m wood-based panel at the center of the wall
Sheathing fastened to the wide face of framing members
Standard shear wall 2x4 studs
16” 16” 16”
Sheathing
Drywall/Sheathing
24” 24”
Midply shear wall
Drywall/Sheathing
Cladding/Sheathing Sheathing
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Nails work in double shear
thus increasing the lateral
load capacity
Greater edge distance -
panel chip out failure is
reduced
Nail head away from panel
surface - nail pull through
failure is prevented
Capable of accommodating
additional sheathing
Reasons for Improved Performance
Nail in single shear
Nail in double shear
Sheathing Stud or
Plate
Grain direction
89 mm
Stud or Plate
38 mm 38 mm
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New construction practices and introduction of Midrise wood
frame buildings create additional demand for lateral load
resistance, so not enough
wall lengths are available
Large openings, long spans,
and concrete toppings have
become common practice,
reducing the available space
for placing the walls
Why Use Midply Shearwalls?
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Testing Program
Performed over 70 full-scale quasi-static and shaking
table tests on Midply walls in several wall configurations
Investigated effects of: stud size, stud spacing, nail
spacing, vertical loads, construction details
Evaluated several types of hold-down connections
Results published in ASCE Journal of Str. Engineering
Erol Varoglu, Erol Karacabeyli, Siegfried Stiemer, and Chun Ni,
2006. “Midply Wood Shear Wall System: Concept and
Performance in Static and Cyclic Testing”, 132(9): 1417-1425
Erol Varoglu, Erol Karacabeyli, Siegfried Stiemer, Chun Ni,
Marlen Buitelaar, and Dan Lungu, 2007. “Midply Wood Shear
Wall System: Performance in Dynamic Testing”, 133(7): 1035-
1042
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Quasi-Static Tests at FPInnovations
(Forintek)
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Type 1 Type 2 Type 3 Type 4 Type 5
Type 1 Type 2
Type 1 Type 2 End Studs
Intermediate
Studs
Stud and Plate Details Considered
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Regular hold-downs
Inverted-triangle hold-
down
Double-shear
hold-downs
Steel rods
Hold-Down Connections Used
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Shake Table Tests at UBC
Effects of stud size, stud
spacing, nail spacing, and
vertical loads were
investigated
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Test Results – Regular vs Midply
-40
-30
-20
-10
0
10
20
30
40
-150 -100 -50 0 50 100 150
Displacement (mm)
Load (
kN
/m)
Specimen m30-01
Specimen S39
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Monotonic & Cyclic Test Results
Average test results of Midply shearwalls
Wall No. Load
Protocol
Vertical
Load
(kN/m)
Pmax
(kN/m) u
(mm)
K
(kN/m/mm)
E
(J/m)
S31/S51/S52 Monotonic 18.2 8.8 105 0.58 -
S37/S38 Monotonic None 8.7 88 0.55 -
S33 Cyclic a 18.2 9.6 78 0.76 3,820
S34/S39/S40 Cyclic a None 9.0 77 0.68 3,210
Average test results of Standard shearwalls
Wall No.
Stud
spacing
(mm)
Load
Protocol
Vertical
Load
(kN/m)
Pmax 1
(kN/m) u
2
(mm)
K 3
(kN/m/mm)
E
(J/m)
M40/M41-1 610 Monotonic 18.2 31.4 121 b 1.66 -
M39 610 Monotonic None 30.2 120 b 1.32 -
M28/M29/M30/M14 a
610 Cyclic a 18.2 28.7 95 1.65 13,655
M31 610 Cyclic a None 27.9 100 1.24 15,790
M32 406 Monotonic 18.2 36.3 103 c 1.57 -
M46 d 406 Cyclic
a None 27.6 83 0.44 8,750
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Factors were investigated by numerical modelling of a four-
storey wood-frame building
4-storey wood-frame structure
Location Surrey, BC, Sa (0.2) =1.0g
Rd = 3.0; Ro = 1.7 same as for standard nailed shearwalls
Designed according to NBCC 2005
22 earthquakes, scaled
to Surrey BC spectrum
Study on Seismic Force Modification
Factors: Rd and Ro
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0
20
40
60
80
100
0 40 80 120 160 200
Storey Drift (mm)
Fre
que
ncy (
%)
Standard shear wall, R=3
Midply shear wall, R=3
Near collapse – standard wall
2.5% inter-storey drift
Near collapse – Midply wall
Results: CDF Function of Storey Drifts
Results confirmed that midply walls can use same R-
factors as regular shearwalls
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Shaking Table Tests of 6-Storey
NEESWood Building
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A total of fourteen 2 x 8 studs
were used at the ends of the
wall to meet the bearing
capacity of plates
Nail spacing
3” in 1 – 3 stories
4” in 4th storey
6” in 5th storey
Framing
2x4” top and bottom plates
2x6 “intermediate studs
2x8” end studs
Details of Midply Walls in the
NEESWood Building
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Details of Midply Walls in the
NEESWood Building
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Details of Midply Walls in the
NEESWood Building
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Continuous Steel Rods
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Northridge ground motion (Canoga Park) with MCE intensity for California Sa=1.4g
Shaking Table Test Video
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Building Performance
Midply and regular shearwalls performed very well
Minimal visible damage on gypsum wall boards and nailed
connections
31
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New Design Provisions for Shearwalls
and Diaphragms in 2014 CSA O86
Tables for resistance replaced with mechanics based approach
The factored shear resistance for a shearwall segment with wood-
based structural panels shall be taken as
the smaller resistance governed by:
▫ Sheathing-to-framing connections
▫ Sheathing panel buckling
Benefits ▫ Design values for all combinations of
sheathing thickness, nail spacing and
diameter
▫ Design values for Midply walls
▫ Values for diaphragms with multiple rows
of fasteners
32
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CSAO86 Requirements for Failure
Mode of Connections
33
For seismic design, sheathing-to-framing connections shall
be designed to fail in fastener yielding modes (d), (e) or (g)
(shown in Clause 12.9.4.2) to ensure sufficient ductility in
the shearwall or the diaphragm
Mode (d) Mode (e) Mode (g)
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Wall Resistance Based on Sheathing
to Framing Connection Resistance
34
𝑉𝑟𝑠 = 𝜙 𝑉𝑑 𝐽𝐷𝑛𝑠 𝐽𝑢𝑠 𝐽𝑠 𝐽ℎ𝑑 𝐿𝑠
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Buckling Resistance of the Sheathing
𝑉𝑟𝑠 = 𝜙 𝑉𝑝𝑏 𝐾𝐷 𝐾𝑠 𝐾𝑇 𝐿𝑠
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Deflection Provisions in 2014 CSA O86
The nail deformation en should be calculated using
▫ Formula for single shear
▫ Load per fastener taken as half of the load applied on the
Midply wall
36
answ db
HHe
Gt
vH
EAb
vH 0025.0
3
2 3
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Other Requirements in CSA O86
Sufficient penetration of nails (min 5d)
Same nail spacing at all locations
A minimum of 3 mm gap between adjacent panels
For studs where panels meet, additional fasteners not
subjected to double shear shall be installed to prevent
detachment of the studs (Figure 11.5.3.4).
37
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Design for Gravity Loads
Check stud compression capacity
Check plate bearing capacity
Recommended to design the pair
of studs as built-up compression
members (columns) according to
CSA O86 Clause 6.5.6.4
38
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Connecting the Built-up Studs
Nails or screws: Connection details
according to Clause 6.5.6.4.2
Bolts: Connection details according to
Clause 6.5.6.4.3
39
Intermediate studs Studs at panels joints
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Design for Lateral Loads
Includes the following steps
Shear capacity
Chord (end-stud) member capacity
Hold-down connection capacity
Shear transfer connection capacity
40
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Design of Shear Capacity
The shear resistance of the wall is the smaller
resistance governed by:
▫ Sheathing-to-framing connections
▫ Sheathing panel buckling
Tables of factored shear
resistance of midply shearwalls
will be provided in CWC’s
Wood Design Manual
41
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Design of the Chord Members
Recommended to design end studs as built-up
columns in accordance with CSA O86 Clause
6.5.6.4
Recommended to use bolted
built-up studs to prevent studs
from separation
42
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Design of the Hold-Downs
Recommend to use continuous steel rods
Shrinkage compensators should be used to control
excessive deformation (for multi-storey buildings)
43
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Hold-Down Details
44
Section A - A
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Design for Shear Transfer
45
Shear transfer at
foundation Shear transfer at floor
Sill plate
Concrete
Sill plate
Floor sheathing
Floor joist
Top plate
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Construction Details for Midply
Shearwalls
Two types of connections
▫ Nails around panel edges to
provide lateral resistance
of the wall (black dots)
▫ Screws or bolts to form built-up
columns, making sure they
don’t contribute to lateral
resistance (white dots)
46
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Construction Details for Midply
Shearwalls
13mm gap between panel edges
and ends of top and bottom plates
3mm gap between adjacent
panels
Min. nail penetration into the side
member in accordance with CSA
O86 Clause 12.9.2.2
Lp 5d
13 mm
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Midply Wall Applications
Four-storey residential buildings in Vancouver at UBC
48
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Midply Wall Application at UBC
Midply walls used in all corridor and party walls
A non-structural parallel wall used for acoustic reasons
Steel rods used to resist up-lift forces
49
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Midply Wall Application in Quebec City
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Midply Application in Japan
Five Storey Elderly Care Facility in Tokyo
With 9,023 m2 this will be the largest wood building ever
built in Japan
First time use of high performance Midply Wall system in
Japan
51
Photo courtesy of COFI / Canada Wood
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Implementation od Midply Walls in
Japan
Lead by Canada Wood, COFI, FPI and 2x4 Association
Based on test results at FPI and additional ones done at the
Centre for Better Living in Tsukuba
52
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Sound Insulation Performance
• Top plates, bottom plates and intermediate studs: 2 x 4 No.2 and Btr SPF
• Studs at panel joints: 2 x 6 No.2 and Btr SPF
• Studs spacing: 610 m on center
• Two layers of 13 mm gypsum board on each side of Midply wall
• The face layer was fastened with screws @300 mm on center and the base
layer was fastened with screws @ 600 mm on center
NRC Report: 2nd Round Wall Sound Insulation Tests: Framed Wall Specimens and STC-Results
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Example of Insulation Detail
Detailed wall assembly for exterior walls should be checked
with building envelope experts
Sheathing membrane
▫ Sheets such as Tyvek or
building paper
▫ Liquid-applied
self-adhered membrane
54
2x 4
Interior gypsum
plyw ood sheathing
rigid insulatinon, based on energy codes
cladding
sheathing membrane
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Conclusions
Midply shearwalls are viable choice of high-strength
shearwalls for use in residential and non-residential wood-
frame construction
Design methodology for such walls is now implemented in
the new 2104 edition of CSAO86
Extensive technical evidence, including full-scale shaking
table tests of a 6-storey building, is available
The procedures for design of Midply wall system were
presented
Hope to see them in some of your next projects
55
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Questions / Comments?
56
This concludes the:
• American Institute of Architects
•Architectural Institute of British Columbia
• Engineering Institute of Canada
Continuing Education Systems Program
Midply Shearwalls: High Capacity Shearwalls for
Midrise Wood Frame Construction
Marjan Popovski
Principal Research Scientist
Marjan.popovski@fpinnovations.ca
Tel. 1-604-222-5739
www.fpinnovations.ca
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