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Midply Shearwall System: Midply Shearwall System: Concept, Performance and Code ImplementationCode ImplementationC. Ni, M. PopovskiFPInnovations, Building Systems
The Wood Products Council and AIA/CES
“The Wood Products Council” is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES) Credit(s) earned onEducation Systems (AIA/CES). Credit(s) earned on completion of this program will be reported to AIA/CES for AIA members. Certificates of Completion for both AIA members and non-AIA members are available upon requestrequest.
This program is registered with AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be ancontent 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.
Learning Objectives
At the end of this program, participants will be able to: Identify the advantages and disadvantages of mid ply shear wall Identify the advantages and disadvantages of mid-ply shear wall
systems from the information provided in the presentation. Identify and explain what the various components (anatomy) of a y p p ( y)
mid-ply shear wall using the various pictures provided in the presentation. Calc late and create details of the mid pl shear from the ario s Calculate and create details of the mid-ply shear from the various examples provided in the presentation.
Verify the validity of using mid-ply shear walls with the information y y g p yon the research and testing that has been done on the mid-ply wall system which will be provided.
FPInnovations - Background
• FPInnovations is a world leader that specializes in the creation of scientific solutions in support to the ppCanadian forest sector’s global competiveness, and responds to the priority needs of its industrial and government membersgovernment members
• With over 550 employees across the country and an annual budget of $90 million it is the world’s largest private, not-for-profit forest products research institute
• This unique forestry research centre is capable of providing complete value chain solutions from forestproviding complete value chain solutions – from forest management and transportation to products, such as structural systems
Midply Walls Outline
• Concept of Midply walls• Background and Research Information• Background and Research Information• Design Approach
C t ti D t il• Construction Details • Application Examples
C l i• Conclusions
Why Midply Shearwall?
Wood frame construction has evolved to include 3 or 4 storey multi-family residence
Large openings long span Large openings, long span, concrete topping have become common practice
New construction practices at times create additional demand on lateral loaddemand on lateral load resistance
Concept of Midply Shearwall
Standard shear wall2x4 studs Sheathing
38 89 mm lumber stud spaced at 406 mm o.c.
16” 16” 16”Drywall/Sheathing
1.22 2.44 m wood-based panel Sheathing fastened to the narrow face of framing members
MidplyTM shear wall Cladding/SheathingSheathing
24” 24”
Drywall/Sheathing 1.22 2.44 m wood-based panel at the center of the wall 38 89 mm lumber stud rotated 90 degree to those in
standard shearwall Sheathing fastened to the wide face of framing members
Drywall/Sheathing
Reasons for Improved Performance
Nails work in double shear thus increasing the lateral load capacity
Greater edge distance panel
Sheathing Stud or
Plate Greater edge distance - panel
chip out failure is reduced
Nail head away from panel Grain 89 mm
Stud or 38 mm 38 mm
y psurface - nail pull through failure is prevented Nail in
single shear Nail in double shear
direction Plate
Capable of accommodating additional sheathing
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 detailsconstruction details
Evaluated several types of hold-down connectionsconnections
Publications
Details of the tests are published in ASCE Journal of Structural Engineering Midply Wood Shear Wall System: Concept and Performance in Static
and Cyclic Testing, 132(9): 1417-1425
Midply Wood Shear Wall System: Performance in Dynamic Testing,
133(7): 1035-1042
Stud and Plate Details Considered
End Studs Type 1 Type 2End Studs
Type 1 Type 2IntermediateStuds
T 1 T 2 T 3 T 4 T 5Type 1 Type 2 Type 3 Type 4 Type 5
Hold-Down Connections Used
Regular hold-down Inverted-triangle hold-
down
Double-shear hold-down
Strip tie
Steel rods
Quasi-Static Tests at FPInnovations (Forintek) Shake Table Tests at the University of BC
Effects of stud size studEffects of stud size, stud spacing, nail spacing, and vertical loads were investigated
Test Results - Monotonic & Cyclic Tests
40
10
20
30
)
-10
0
10
Load
(kN
/m)
-30
-20
Specimen m30-01S i S39
-40-150 -100 -50 0 50 100 150
Displacement (mm)
Specimen S39
Test Results - Monotonic & Cyclic Tests
Average test results of Midply shearwallsStud Load Vertical P 1 2 K 3 EWall No. spacing (mm)
Load Protocol Load
(kN/m)
Pmax (kN/m)
u (mm)
K (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 610 C li a 18 2 28 7 95 1 65 13 655M28/M29/M30/M14 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
Wall No. Load P t l
Vertical L d
Pmax (kN/ )
u ( )
K (kN/ / )
E (J/ )
Average test results of standard shearwalls
Protocol Load (kN/m) (mm) (kN/m/mm) (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 210S34/S39/S40 Cyclic None 9.0 77 0.68 3,210
Design Possibilities for Midply Shearwalls
Canada NBCC Alternate Solution Method (based on peer-reviewed
evidence). A proposal on Midply wall is being prepared for implementationA proposal on Midply wall is being prepared for implementation
in 2014 CSAO86
USAUSA Alternate Solution Method. Design values can be established
by using ICC Evaluation Criteria AC 130 - Prefabricated Wood Shear Panels
A proposal for AF&PA SDPWS will be prepared
Code Proposal for 2014 CSAO86 in Canada
Lateral Load ResistanceMidply shearwall = 2 0 standard shearwall
Shear strength of a nailed joint in
Midply shearwall = 2.0 standard shearwall
Comparison of joint load-slip response under reversed cyclic test
double shear is about twice that in single shear
Lateral load capacity may be further 0
2
4
6
8
d (k
N)
Lateral load capacity may be further increased through the elimination of failure modes observed in standard shearwalls
-8
-6
-4
-2
0-30 -20 -10 0 10 20 30
Load
shearwalls Displacement (mm)
Joint in double shear Joint in single shear
Code Proposal for 2014 CSA O86
Deflection
answ dbHHe
GtvH
EAbvH
0025.032 3
bGtEAb3
The nail deformation en should be calculated based on the formula for single shear and load per fastener shall be taken as half of the load applied on the midply walltaken as half of the load applied on the midply wall
Study on Seismic Force Modification Factors Rd, Ro
Rd = 3.0, Ro = 1.7 same as for standard nailed shearwallsshearwalls
Factors were confirmed by numerical modelling of a four-storey wood-frame building
4-storey wood-frame structure
Surrey, BC, PGA = 0.51g
Rd = 3.0; Ro = 1.7
Designed according to NBCC
20052005
22 earthquakes, scaled to 0.51g
Case Study Results – CDF Function of Storey Drifts
100
60
80
%)
40
60
Freq
uenc
y (%
Standard shear wall, R=3Midply shear wall R=3
20
F Midply shear wall, R=3
Near collapse – standard wall
2.5% inter-storey drift
00 40 80 120 160 200
Storey Drift (mm)
Near collapse – Midply wall
Storey Drift (mm)
ICC-ES AC130 Evaluation Criteria in the US
• Developing design values and assigning an R-factor for new wood shearwall assemblies (such as Midply ( p ywalls) in the US can be done by using the ICC-ES AC-130 evaluation criteria entitled ”Acceptance Criteria for Prefabricated Wood Shear Panels”Criteria for Prefabricated Wood Shear Panels
• The AC-130 criteria is based on showing equivalency of the seismic performance of the new assemblies (Midply walls) with respect to lumber-based nailed shearwalls
Midply Shearwalls in the US - AC130 Evaluation
IBC allowable shear for Midply shearwalls (Seismic)The allowable shear shall be the lesser of the allowable shear
D ift Li it (5 1 3 1 1)
The allowable shear shall be the lesser of the allowable shear based on a drift limit or strength limit obtained from first-cycle load-displacement backbone curve Drift Limit (5.1.3.1.1)
a) Maximum inelastic response displacement, x = min (2.5%H, SLS)b) Strength Design level response displacement, xe = x (I / Cd)c) Force corresponding to xe is Pxe
d) Allowable shear, PDL = 0.7 Pxe
e) Drift corresponding to PDL is DL) p g DL DL
Strength Limit (5.1.3.1.3)a) Allowable shear, PSL = Pmax / 2.5 b) Drift corresponding to P is b) Drift corresponding to PSL is SL
Midply Shearwall Envelope Curve for AC130
40
10
20
30
-10
0
10
Load
(kN
/m)
-30
-20
10L
Specimen m30 01
-40-150 -100 -50 0 50 100 150
Displacement (mm)
Specimen m30-01
p ( )
Evaluation of Midply Shearwall - AC130
a) = min ( ) = 61 mm
Drift Limit (Seismic)40a) x = min (2.5%H, SLS) = 61 mm
b) xe = x (I / Cd) = 15.25 mm
) P 17 0 kN/30
35
40
Pmax
c) Pxe = 17.0 kN/m
d) PDL = 0.7 Pxe = 11.9 KN/m
) 15
20
25
Load
(kN
/m)
Pxe
0.8Pmax
e) DL = PDL = 7.5 mm
Strength Limit (Seismic) 5
10
15
Specimen m30-01
PDL PSL
∆a) PSL = Pmax / 2.5 = 12.3 KN/m
b) SL = PSL = 7.9 mm
00 40 80 120 160
Displacement (mm)
∆2.5%H ∆SLS ∆uδxe∆DL
∆SL
Evaluation of Midply Shearwall - AC130
IBC allowable shear for Midply shearwall (Wind)The allowable shear shall be the lesser of the allowable shearThe allowable shear shall be the lesser of the allowable shear based on a drift limit or strength limit obtained from first-cycle load-displacement backbone curve
Drift Limit (5.1.3.1.2)a) Allowable shear, PDL = load corresponding to DL = H / 180
Strength Limit (5.1.3.1.3)a) Allowable shear, PSL = Pmax / 2.0 b) Drift corresponding to P is b) Drift corresponding to PSL is SL
Evaluation of Midply Shearwall - AC130
Drift Limit (Wind) 40
b) PDL = PDL = 16.2 KN/m
a) DL = H / 180 = 13.6 mm
25
30
35
) 0.8Pmax
Pmax
15
20
25
Load
(kN
/m)
PSL
PDL
Strength Limit (Wind)
a) PSL = Pmax / 2.0 = 15.4 KN/m
b) 12 1 0
5
10
Specimen m30-01∆DL
b) SL = PSL = 12.1 mm 00 40 80 120 160
Displacement (mm)
∆u∆SL
Using Midply Shearwall in US - AC130 Evaluation
Light-framed walls sheathed with wood structural panels (ASCE-7)
Response Modification Coefficient: R = 6.5
System Over-strength Factor: 0 = 3
Deflection Amplification Factor: Cd = 4
C tibilit ith b S i i F R i ti S t (AC 130)
Ductility (5.2.2) : u / ASD 11 (test result = 14)
Compatibility with above Seismic-Force Resisting System (AC 130)
Drift capacity (5.2.3): u 0.028 H (68 mm) (test result = 106 mm)
Over-strength (5.2.4): 2.5 ≤ Pmax / PASD ≤ 5.0 (test result = 2.6)
Design of Midply Shearwalls
Design for gravity loads
Check stud compression capacity
Check plate bearing capacity
Recommend to design pair studs as Recommend to design pair studs as built-up columns in accordance with NDS Clause 15.3
Column stability factor, Cp, calculated in accordance with NDS Clause 15.3.2
Design of Midply Shearwalls
Connection of the built-up studs
Nails or screws: Connection details in
accordance with NDS Clause 15.3.3
Bolts: Connection details in accordance with
NDS Clause 15.3.4
Intermediate studs
Studs at panels joints
Design of Midply Shearwalls
Design for lateral loads
Shear capacity
Chord (end-stud) member capacity
Hold-down connection capacity
Shear transfer connection capacity
Design of Midply Shearwalls
fDesign of shear capacity
Midply shearwall capacity = 2.0 x standard
shearwall (same nail spacing and diameter)
Design of Midply Shearwalls
Design of the chord members
Recommend to design end studs as
built-up columns in accordance with
NDS Clause 15.3
Recommend to use bolted built-up studs
to prevent studs from separation.
Design of Midply Shearwalls
Design of the hold-downs
Recommend to use continuous steel rods
Shrinkage compensators should be used
to control excessive deformation (for
multi-storey buildings)
Design of Midply Shearwalls
Design of hold-downs (con’t)
Steel rodStud
Steel rodStud
Bottom plateSteel plate
Steel rodStudA A
Bottom plateSteel plate
Section A - A
Design of Midply Shearwalls
Design for shear transfer
Sill platepFloor sheathing
Floor joistSill plate
Top plateConcrete
Shear transfer at S f ffoundation Shear transfer at floor
Construction Details for Midply Shearwalls
Two types of connections
Nails around panel edges to provide lateral resistance of the wall
Screws or bolts to form built-up columns (making sure they don’t contribute to lateral resistance)
Construction Details for Midply Shearwalls
1/2 inch gap between panel edges and ends 1/2 inch gap between panel edges and ends of top and bottom plates
1/8 inch gap between adjacent panels1/2 i h
Min. nail penetration into the side member in
1/2 inch
accordance with NDS Clause 11.1.5.5Lp 6d
Midply Wall Application
Four-storey residential building in Vancouver Midply walls used in all corridor and party walls
A t t l ll l ll d f ti A non-structural parallel wall used for acoustic reasons Steel rods used to resist up-lift forces
Midply Wall Application
Shaking Table Tests of 6-Storey NEESWood Building Details of Midply Walls in the NEESWood Building
Nail spacing3” i 1 3 t i 3” in 1 – 3 stories
4” in 4th storey 6” in 5th storey
Framing 2 x 4 lumber for top and bottom
plates 2 x 6 lumber intermediate studs 2 x 8 lumber for 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
Details of Midply Walls in the NEESWood Building Details of Midply Walls in the NEESWood Building
Shaking Table Test of 6-Storey NEESWood Building
Earthquake record
Northridge ground motion recorded at themotion recorded at the Canoga Park
Earthquake intensity
Maximum Credible Earthquake (MCE) for California
Insulation Detail Example
Detailed all assembl for e terior
2x 4 rigid insulatinon,
Detailed wall assembly for exterior
walls should be checked with
building envelope professionals
Interior gypsum
based on energy codes
cladding
building envelope professionals
Sheathing membrane can use
sheets such as Tyvek or building
plywood sheathing
sheathing membrane
paper
It can also be liquid-applied self-
adhered membrane
Conclusions
The Midply shearwall is a new wall system which provides much greater lateral load capacity than aprovides much greater lateral load capacity than a standard shearwall with same length and same specifiacations
The Midply shearwall can be used in residential or non-residential wood construction where demand for lateral load capacity is highlateral load capacity is high
Extensive technical evidence including a full-scale shaking table tests of a 6-storey building with Midply walls is available
Procedures for design of Midply wall system are presentedpresented
Thank You
TM
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