Midply Shearwalls: High Capacity
Shearwalls for Midrise Wood
Frame Construction
Marjan Popovski, Ph.D., P.Eng.
Principal Scientist and Quality Manager
Advanced Building Systems Department
Vancouver
October 30, 2014
Copyright Materials
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Program Education Credit Information
3

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 nonAIA, 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.
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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
Research: Sustainable Forestry  Sustainable Building Systems
5
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Presentation Outline

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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
Photo Courtesy of WoodWorks!
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Midrise Construction in BC
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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
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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
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Midrise Construction in the US
 Already Code Approved in the US
 Adoption varies by regions and jurisdictions
Photo: BC WoodWorks!
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5-7 Storey Apartments in the US
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Regular vs Midply Shearwall
2x4 studs
Standard shear wall
16”



16”
Sheathing
16”
Drywall/Sheathing
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
Midply shear wall
24”
Sheathing
Cladding/Sheathing
24”
Drywall/Sheathing



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
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Reasons for Improved Performance
 Nails work in double shear
thus increasing the lateral
load capacity
Stud or
Plate
 Greater edge distance panel chip out failure is
89 mm
reduced
Grain
direction
 Nail head away from panel
surface - nail pull through
Nail in
single shear
failure is prevented
 Capable of accommodating
additional sheathing
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Sheathing
38 mm
38 mm
Stud or
Plate
Nail in double
shear
Why Use Midply Shearwalls?
 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
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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): 10351042
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Quasi-Static Tests at FPInnovations
(Forintek)
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Stud and Plate Details Considered
End Studs
Type 1
Type 2
Intermediate
Studs
Type 1
Type 2
Type 1
Type 2
Type 3
Type 4
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Type 5
Hold-Down Connections Used
 Regular hold-downs
 Inverted-triangle holddown
 Double-shear
hold-downs
 Steel rods
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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
Load (kN/m)
20
10
0
-10
-20
-30
-40
-150
Specimen m30-01
Specimen S39
-100
-50
0
50
Displacement (mm)
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100
150
Monotonic & Cyclic Test Results
Average test results of Midply shearwalls
Stud
Vertical
Load
Pmax 1
K3
E
u 2
Wall No.
spacing
Load
Protocol
(kN/m) (mm) (kN/m/mm) (J/m)
(mm)
(kN/m)
M40/M41-1
610 Monotonic 18.2
31.4
121 b
1.66
b
M39
610 Monotonic None
30.2
120
1.32
a
M28/M29/M30/M14 610
Cyclic
18.2
28.7
95
1.65
13,655
a
a
M31
610
Cyclic
None
27.9
100
1.24
15,790
c
M32
406 Monotonic 18.2
36.3
103
1.57
d
a
M46
406
Cyclic
None
27.6
83
0.44
8,750
Average test results of Standard shearwalls
Load
Protocol
S31/S51/S52 Monotonic
S37/S38
Monotonic
S33
Cyclic a
S34/S39/S40 Cyclic a
Wall No.
Vertical
Load
(kN/m)
18.2
None
18.2
None
Pmax
(kN/m)
8.8
8.7
9.6
9.0
u
(mm)
105
88
78
77
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K
(kN/m/mm)
0.58
0.55
0.76
0.68
E
(J/m)
3,820
3,210
Study on Seismic Force Modification
Factors: Rd and Ro
 Factors were investigated by numerical modelling of a fourstorey 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
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Results: CDF Function of Storey Drifts
 Results confirmed that midply walls can use same Rfactors as regular shearwalls
100
Frequency (%)
80
60
Standard shear wall, R=3
Midply shear wall, R=3
40
2.5% inter-storey drift
20
Near collapse – standard wall
Near collapse – Midply wall
0
0
40
80
120
Storey Drift (mm)
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160
200
Shaking Table Tests of 6-Storey
NEESWood Building
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Details of Midply Walls in the
NEESWood Building
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
A total of fourteen 2 x 8 studs
were used at the ends of the
wall to meet the bearing
capacity of plates
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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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Shaking Table Test Video
Northridge ground motion (Canoga Park) with MCE intensity for California Sa=1.4g
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Building Performance
 Midply and regular shearwalls performed very well
 Minimal visible damage on gypsum wall boards and nailed
connections
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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 woodbased structural panels shall be taken as
the smaller resistance governed by:
▫
▫
Sheathing-to-framing connections
Sheathing panel buckling
 Benefits
▫
▫
▫
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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
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CSAO86 Requirements for Failure
Mode of Connections
 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)
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Mode (e)
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Mode (g)
Wall Resistance Based on Sheathing
to Framing Connection Resistance
𝑉𝑟𝑠 = 𝜙 𝑉𝑑 𝐽𝐷 𝑛𝑠 𝐽𝑢𝑠 𝐽𝑠 𝐽ℎ𝑑 𝐿𝑠
34
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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
 sw
2vH 3 vH
H


 0.0025Hen  d a
3EAb Gt
b
 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
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Other Requirements in CSA O86
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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).
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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
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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
Intermediate studs
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Studs at panels joints
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Design for Lateral Loads
Includes the following steps




40
Shear capacity
Chord (end-stud) member capacity
Hold-down connection capacity
Shear transfer connection capacity
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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
Section A - A
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Design for Shear Transfer
Sill plate
Floor sheathing
Sill plate
Concrete
Shear transfer at
foundation
45
Floor joist
Top plate
Shear transfer at floor
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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)
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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
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13 mm
Midply Wall Applications
 Four-storey residential buildings in Vancouver at UBC
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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
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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
Photo courtesy of COFI / Canada Wood
51
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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
2x 4
Interior
gypsum
rigid
insulatinon,
based on
energy codes
cladding
plyw ood
sheathing
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sheathing
membrane
Conclusions
 Midply shearwalls are viable choice of high-strength
shearwalls for use in residential and non-residential woodframe 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
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Questions / Comments?
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
[email protected]
Tel. 1-604-222-5739
Follow us on
www.fpinnovations.ca
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