Effective Use of the New SDI Roof Deck Design Manual

Presenter: Michael Martignetti, PE, LEED AP BD+CEngineering ManagerCanam Buildings

Referred to as “RDDM” in Presentation

Basis of Presentation

Available for Purchase at www.sdi.org

What is Roof Deck??• Encloses Building from Wind• Provides Fire Resistance as Part of UL Assembly• Structural Base of Roof Membrane• Resists Dead, Snow, Roof Live, Seismic and Wind Loads• Transfers Wind and Seismic Loads to Vertical Components of Lateral Force Resisting Systems through Diaphragm Action

Typical Roof Assemblies

Roof Deck Not Intended to Be Watertight in Any Circumstance!!

Manufacturing Roof Deck

COILS

LINE 1

LINE 3

LINE 2

OVERHEAD CRANE

Steel Coils

Steel Properties

ASTM A1008 – Cold Rolled Steel

ASTM A653 – Galvanized Steel(ASTM A924 – Zinc Coating)

Fy minimum = 33 ksiFu minimum = 45 ksi

Typical Gages for Roof Deck – 22 gage thru 16 gage

Actual Steel Thickness to be at Least 95% of Design Thicknessi.e. 22 gage – (0.0295” Design x 0.95 = 0.028” Minimum)

AISI S100 Sections A2.1 and A2.2

Fy = 85.9 ksiFu = 88.7 ksi

Steel Properties

Roll Forming

‐ Load Coil‐ Line Up Steel In Roll Former‐ Roll Form

Roll Forming

‐ Shear‐ Stack‐ Bundle‐ Ship

Standard Roof Deck Types

B Deck[Wide Rib (WR) Deck]

N Deck[Deep Rib (DR) Deck]

Most Common Roof Decks1 ½” and 3” Options

F Deck[Intermediate Rib (IR) Deck]

A Deck[Narrow Rib (NR) Deck]

Other Options for 1 ½” DeckNarrower Low Ribs for Thin Insulation Scenarios

Long Span Roof Deck

•Used to Span Longer Distances and/or Carry Heavier Loads• Made By Some Deck Manufacturers Although Profiles Vary

Cellular Roof Deck

• Flat Panel Welded or Mechanically Attached to Bottom of Profile• Flat Appearance from Underside• Can Span Longer Distances and/or Carry Heavier Loads

Available in 1 ½”, 3”, 4 ½”, 6” and 7 ½” By Some Manufacturers (3” Shown)

Acoustic Deck

Field Installed Acoustic Batts Shop Installed Acoustic Batts

Standard Cellular

‐ Perforations in Deck Allow Sound to Pass Through and Be Absorbed by Fiberglass Batts‐ Reduces Sound Reverberation (Echo)‐ Does Not Prevent Sound Passing Through Floor or Provide R Value

Noise Reduction Coefficient‐Measure of Performance for Acoustic Deck‐ Performance is a Function of Roof Assembly – Deck + Batts + Built Up Insulation‐Most Tests Based on 2” Poly‐Isocyanurate Built Up Roofing (Most Common)‐ Reduction of Reverberation‐ Deck Tested At Multiple Frequencies‐ NRC Obtained By Averaging Results of 250, 500, 1000 and 2000 Hz

• Prime Paintedo Cold Rolled (CR) Substrate (Bare Steel)o Typically Available in Gray or Whiteo Provisional Coating (Approx 0.3 mil Thickness)o Applied Via Industrial Coating Line

• Galvanizedo G60 and G90 Most Common

• Galvanized + Primero Provisional Gray or White Primer (Same as CR)o Allows for Easier Adhesion of Field Paint

Deck Finishes

Galvanized Coatings

Heavier Coatings Available Although Not Common for Buildings

G165 or G235 Coatings Common for Bridge Form Applications

Design References

Non effective area (positive bending)

Properties

Properties

Fy = 33 ksi, Fu = 45 ksiP = Positive bendingN = Negative bending

C3.1.1‐1 Mn = SeFy

Loads

Vertical LoadsDownwardUpwardsConcentratedShear Web Crippling

Lateral LoadsCompressionDiaphragm

3N2012’ span

Loads

One Span+ M = 0.125 wL2 = 0.6 Fy Sp

Two Span+ M = 0.07 wL2 = 0.6 Fy Sp‐M = 0.125 wL2 = 0.6 Fy Sn

Three Span+ M = 0.08 wL2 = 0.6 Fy Sp‐M = 0.10 wL2 = 0.6 Fy Sn

Gravity loads and tables

Δ1 = 22.46 wL4 / (E Ip) < L/240

Δ2 = 9.33 wL4 / (E Ip) < L/240

Δ3 = 11.92 wL4 / (E Ip) < L/240

Capacities, Gravity

One Span‐M = 0.125 wL2 = 0.6 Fy Sn

Two Span‐M = 0.07 wL2 = 0.6 Fy Sn+ M = 0.125 wL2 = 0.6 Fy Sp

Three Span‐M = 0.08 wL2 = 0.6 Fy Sn+ M = 0.10 wL2 = 0.6 Fy Sp

Capacities, Uplift

If X < 0.25 be = B + 6” > 12”If X > 0.25 be = B + 18” – 3/X > 24” – 3/X

XL

Example: If L = 12 ft, and XL = 6 ft, and B = 10”X = 0.5be = 10 + 18” – 3/0.5 > 24” – 3/0.5be = 22” > 18”. Use be = 22”

Concentrated Loads

L = SpanX = % of Span

Capacities, Shear

C3.2.1‐1 Vn = AwFv

ANSI/SDI‐RD1.0“Deck ends over supports shall be installed with a minimum end bearing of 1 ½” .“

If N < 1 ½”, or high shear loads are expected, the designer should check the deck for web crippling.

Crippling

WEB YIELDING

FLANGE CURLING

Crippling

Crippling

Web Yields Flange Curls

Web YieldsFlange Curls

Crippling

Capacities, CripplingAllowable Loads

TFE = 504 plf 504 plf = 300 plf + wL/2

wmax = 34 psf

Capacities, Crippling

3N2012’ span

300 plf curb

Pn = A ( 1 + B (N)0.5) derived from AISI S‐100 Pa= Pn / ΩPa= 476 ( 1 + 0.74 (1.5)0.5) / 1.8 = 504 plfPa = 476 ( 1 + 0.74 (2.5)0.5) / 1.8 = 573 plfPa = 476 ( 1 + 0.74 (3.5)0.5) / 1.8 = 630 plf

Capacities, Crippling

Capacities, Axial

C3.4.1‐1 Pn = AeFn

Capacities, Diaphragm

Supports• Welds• Screws• Pins (Powder Actuated or Pneumatic)

Fasteners During construction they secure the sheets from sliding

Critical for horizontal (diaphragm) shear loads and/or uplift

Side Laps• Welds• Screws• Button Punches

Arc Spot Welds(Puddle Welds)

Typical Welding ElectrodesE6022 – 22 gage or ThickerE7014 – Thinner than 22 gage

Sheet Steel Welding AWS D1.3

Weld Washers Only For Gages Less than 22 (Not Including 22 gage)

Per SDI No More Than 1/16” Gap Between Deck and Support

Mechanical FastenersScrews Pins

• Typical for Attachment to Light Gage Framing• Also Used for Steel Joist or Beam Supports Especially with Fastener Manufacturer Tools

• Draw Deck Down to Supports• No Fire Watch• #10, #12, #14, ¼” Diameters (#12 Most Common)• Drill Points No. 3 thru 5• Performance Based on Specific Manufacturer

Drill Point Max Total Material Thickness3 5/32"4 5/16"5 1/2"

• Powder Actuated or Pneumatic• Quick Installation• No Fire Watch• Performance Based on Specific Manufacturer

Attachment Patterns(Deck Panel Coverage (inches) / No Fasteners Per Sheet at Each Support)

Side Lap FastenersWelds

• Puddle or Fillet• Difficult to Make for Lighter Gages• Not Recommended for 22 Gage or Thinner

Screws• Easiest Installation if Horizontal Runout Exists• Visible from Underside

Button Punches• Must Have Interlocking Side Lap• Proprietary Systems Available• Difficult to Make for Heavier Gages

Uplift / ShearBased on 2007 AISI S100 Design Specification

TensionPnt = 0.8(Fu/Fy)2 x t(d‐t) x Fu (Eq. E2.2.2‐2)

Ω = 2.50 φ = 0.60

ShearPnv = See AISI for Different Cases

(Eqs. E2.2.1.2‐1 thru 4)

Puddle Welds Pins

Consult Specific Pin Manufacturer for Information on Tension and ShearCapacity as These Values are TypicallyBased on Product Testing…

Values for Uplift & Shear of Puddle Welds Found in

Tables 8.1 and 8.2 of RDDM(See Next Slide)

Uplift / ShearBased on 2007 AISI S100 Design Specification

TensionLesser of Pull‐Out, Pull‐Over and Tensile Capacity of Screw per Screw Manufacturer:

Pull‐OutPnot = 0.85t2dFu2 (Eq. E4.4.1‐1)

Ω = 3.00 φ = 0.50

Pull‐OverPnov = 1.5t1dwFu1 (Eq. E4.4.2‐1)

Ω = 3.00 φ = 0.50

Fu1 and t1 are for Steel Contacting Screw HeadFu2 and t2 are for Steel Engaging Screw Threads

Screws

ShearLesser of Tilting, Bearing and Shear Capacity of Screw per Screw Manufacturer:Pns = See AISI for Different Cases

(Eqs. E4.3.1‐1 thru 5)

Values for Tension, Pull‐Out, Pull‐Over and Shear of

Screws Found in Tables 9.1 thru 9.4 of RDDM

Diaphragm Shear• Important Design Parameter When Specifying Roof Deck

• Subject of Separate Webinar

• Based on SDI Diaphragm Design Manual‐ 3rd Edition Current‐ 4th Edition Expected Soon

• Important to Remember Interaction of Shear and Uplift

Available for free download at www.sdi.org. Hard copies available for nominal fee.

Primary Reference for Construction Practices with Steel Deck

SDI Manual of Construction

Deck Bearing

Ends of Sheets Generally Lap for Nestable Deck

Heavier Gages or Interlocking Deck May Require Butted Ends

SDI Requires at Least 1 ½” Bearing in Strong Direction!!(1/2” Minimum in Weak Direction)

Accessories

Ridge Plate

Sump Pan

Butt StripValley Plate

Finish Strip

Spray Fireproofing and UL Paint• SFRM = Spray On Fire Resistive Material• Galvanized Deck Should Generally Be Specified if Deck will Receive SFRM• Specify a UL Approved Primer if Primed Deck is to Receive SFRM• Acoustic Deck CANNOT Receive SFRM•U.L. Approved Paint Has Been Put Through Fire Testing by U.L. to Confirm Adhesion At High Temperatures

RDDM TablesA good deal of technical data is presented in tables for quick reference.

Example of Table from RDDM…

Example of Table from RDDM (cont)

RDDM ExamplesMany examples are worked through for common calculations that designers face.

RDDM References

Questions???

SDI Managing Director – Bob PaulOffice Location – Pittsburgh, PAPhone – (412) 487‐3325Email – bob@sdi.orgWebsite – www.sdi.org

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