www.fpinnovations.ca

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

www.fpinnovations.ca

© 2010 FPInnovations. All rights reserved. Copying and redistribution prohibited. TM Fpinnovations, its marks and logos are trademarks of FPInnovations.