midply shearwalls: high capacity shearwalls for midrise...

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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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.

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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


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


Presentation Outline

Midrise Wood Frame Construction

Concept of Midply Walls

Background and Research Information

Design Approach

Construction Details

Application Examples

Conclusions


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!


Midrise Construction in BC

8


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



Handbook

With support from NRCan working on a Handbook for


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


Midrise Construction in the US

Already Code Approved in the US

Adoption varies by regions and jurisdictions

11

Photo: BC WoodWorks!


5-7 Storey Apartments in the US

12


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


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


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?


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


Quasi-Static Tests at FPInnovations

(Forintek)


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


Regular hold-downs

Inverted-triangle hold-

down

Double-shear

hold-downs

Steel rods

Hold-Down Connections Used


Shake Table Tests at UBC

Effects of stud size, stud

spacing, nail spacing, and

vertical loads were

investigated


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


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


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


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


Shaking Table Tests of 6-Storey

NEESWood Building


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


Details of Midply Walls in the

NEESWood Building


Continuous Steel Rods

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Northridge ground motion (Canoga Park) with MCE intensity for California Sa=1.4g

Shaking Table Test Video


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 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

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CSAO86 Requirements for Failure

Mode of Connections

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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)


Wall Resistance Based on Sheathing

to Framing Connection Resistance

34

𝑉𝑟𝑠 = 𝜙 𝑉𝑑 𝐽𝐷𝑛𝑠 𝐽𝑢𝑠 𝐽𝑠 𝐽ℎ𝑑 𝐿𝑠


Buckling Resistance of the Sheathing

𝑉𝑟𝑠 = 𝜙 𝑉𝑝𝑏 𝐾𝐷 𝐾𝑠 𝐾𝑇 𝐿𝑠


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

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answ db

HHe

Gt

vH

EAb

vH 0025.0

3

2 3


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).

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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

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Intermediate studs Studs at panels joints


Design for Lateral Loads

Includes the following steps

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


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

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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


Hold-Down Details

44

Section A - A


Design for Shear Transfer

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Shear transfer at

foundation Shear transfer at floor

Sill plate

Concrete

Sill plate

Floor sheathing

Floor joist

Top plate


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

13 mm


Midply Wall Applications

Four-storey residential buildings in Vancouver at UBC

48


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


Midply Wall Application in Quebec City


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

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Photo courtesy of COFI / Canada Wood


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

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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


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

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2x 4

Interior gypsum

plyw ood sheathing

rigid insulatinon, based on energy codes

cladding

sheathing membrane


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

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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


Marjan Popovski

Principal Research Scientist

[email protected]

Tel. 1-604-222-5739

www.fpinnovations.ca

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mailto:[email protected]

http://www.fpinnovations.ca/

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