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NEES 7TH ANNUAL MEETINGSeismic Mitigation in a Flat World
NEES WITHOUT BORDERS
Corrugated Sheet Steel Shear Walls
Corrugated Sheet Steel Shear Wall
• Corrugated metal deck
• Metal studs
• Screws
•
Type II Construction
•
Off the shelf components
•
Bearing Wall System
•
Light-Framed Cold-formed Steel Framing
Promising Applications
•
Multi-unit Residential
•
Dormitories
•
Hotels / Motels
•
Retail / Commercial
•
Penthouses
•
Seismic retrofit
The Wave of The Future
- Shop assembled
- Easily transported
- Standardized
- Improved quality
- Faster construction
- BIM ready
Pre-fabricated
Structural Systems
Conventional Lateral Systems
•
Steel Tension only Flat Straps
•
Steel Frames
•
Concrete Block
•
Proprietary Wall Board
•
Proprietary Braced Panels
•
Flat Steel Sheets
A lateral system that is:
The Missing link…
-
Non-combustible
- Light
- Strong
- Durable
- Economical
The Solution…
Corrugated Sheet Steel Shear Walls
Research Program:
•
Funded by the Charles Pankow
Foundation
•
Testing at the University of California, Berkeley
•
Principal Investigator, Bozidar
Stojadinovic
•
Project Champion, Steven Tipping, SE
•
Non-Proprietary
44 Wall Specimens Tested
20, 18, 16 and 14ga
Primary Test Variables:
•
Metal stud gauge
22, 20, and 18ga
•
Corrugated Sheathing
#10, #12 and #14
•
Self-tapping Screws
4’-0”
x 8’-2”
Specimen Types:
•
Typical Panel
2’-0”
x 8’-2”
•
Narrow Panel
•
Component Variables3 specimens w/ sheetrock
2 specimens double-sided
2 specimens w/ 4”
dia. holes
2 specimens w/ 2”x4”
holes
Test Apparatus
Panel Frame
Actuator Connection
Frame Base
Panel Connection at Base
Panel Connection at Top
Loading Protocol
• Follows ICC-ES AC154 • Full-reversal cyclic shear loading, 74 cycles to 5% drift• Frequency = .2 cycle per second
Dis
plac
emen
t
Cycles
Force-Displacement Curve for Typical Panel
Video Not Available
Video Not Available
Failure Sequence:
1.
Screw gouging stud/decking
2.
Tension field warping of decking
3.
Tension failure of screw
Screw Gouging of Decking
Tension Field Warping of Deck
Tension Failure of Screw
Failure Locations
Top Right
Bottom Right
Horizontal Seam
Negligible Effects due to Small Openings
Testing Summary:
•
Gypsum wallboard does not increase strength
•
Small openings are O.K.
•
No seam blocking required
•
Double sided = double strength
•
3x stronger than equivalent plywood sheathed panel
•
2x stronger than equivalent proprietary panel
•
Strong, stiff, predictable behavior
Specimen #9 Force-Displacement Curve
(18 gauge decking, 16 gauge studs, #12 @ 3”
oc)
Group #14 Backbone Curve (18 ga. decking, 16 ga. studs, #12 @ 3”
oc)
Group Summary of Backbone Curves
PLYWOODON WOOD
STUDS
STEEL SHEETS
PLYWOOD ONMETAL STUDS
FLAT STRAP
Steel SCBFR=6, Cd=5
Corrugated Metal Decking Shear Wall Design Table
Panel Assembly20 ga. studs 18 ga. studs 16 ga. studs
#12 Screws #12 Screws #12 Screws #14 Screws
Sheathing Screw Spacing
Shear(plf)
Shear(plf)
Shear(plf)
Shear(plf)
22 ga. deck6”
o.c. 1,173 1,505 1,836 ---
3”
o.c. --- 3,050 3,290 ---
18 ga. deck 3”
o.c. --- 4,144 5,164 5,874
Nominal Shear Capacities for Wind and Seismic Forces for Shear Walls Framed with Cold Formed Steel Studs Sheathed with Corrugated Metal Decking
Determining Seismic Response Parameters: R, Ω, Cd
•
Traditional approach per 1999 SEAOC Blue Book/2000 NEHRP commentary
•
Proposed Approach: ATC 63
ASCE 7-05 Table 12.2-1 Traditional Approach
Design Coefficients and Factors for Seismic Force Resisting Systems
Light-Framed Walls SheathedWith Wood Or Steel Sheets
6.5 3 4
Light-Framed Walls With Corrugated Sheet Steel 5.5* 2.5* 3.25*
Light-Framed WallsWith Flat Straps 4 2 3.5Light-Framed WallsWith Other Materials 2 2.5 2
R Wo Cd
*Proposed
Corrugated Metal Decking Shear Wall Design TableTraditional Approach
Panel Assembly20 ga. studs 18 ga. studs 16 ga. studs
#12 Screws #12 Screws #12 Screws #14 Screws
Sheathing Screw Spacing
Shear(plf)
Shear(plf)
Shear(plf)
Shear(plf)
22 ga. deck6”
o.c. 469 602 734 ---
3”
o.c. --- 1,220 1,316 ---
18 ga. deck 3”
o.c. --- 1,658 2,065 2,350
Allowable Shear Capacities for Wind and Seismic Forces for Shear
Walls Framed with Cold Formed Steel Studs and Sheathed with Corrugated Metal Decking (R
=5.5, Cd
=3.25)
ATC 63 Approach
Anticipated seismic response factors for light-framed walls sheathed with:
WoodR = 6 Ω
= 3 Cd
= 4
Corrugated Sheet SteelR = 5 Ω
= 2.5 Cd
= 3.25
Next StepsAdditional Wall Testing:
•
8 x 8 shear panels
•
Fire testing of assemblies
•
Acoustical testing of assemblies
Code Adoption:
•
ATC 63 peer review
•
BSSC and ASCE 7 code committee approvals
•
Final IBC structural classification
Download report:
•
FTP site: ftp.tippingmar.com
•
Username: metalwall
•
Password: screw