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Steel Deck Diaphragm Calculator

The Steel Deck Diaphragm Calculator provides diaphragm shear strengths of a steel deck when using Simpson Strong-Tie Strong-Drive® screws. The Diaphragm Capacity Tables calculator can be used to develop a table of diaphragm capacities based on the effects of combined shear and tension, or the Optimized Solutions can be used to provide optimized fastening solutions for a given shear and uplift.

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Optimized Solutions

Optimized Solutions

Design and optimize fastening solutions for a steel deck diaphragm.

Diaphragm Capacity Tables

Diaphragm
Capacity
Tables

Develop tables of steel deck diaphragm capacities for a given shear and uplift load.

Manufacturer Specific Information

Other Diaphragm Tables

Access manufacturer specific diaphragm capacity tables and information related to Simpson Strong-Tie Strong-Drive screws.

Manufacturer Specific Diaphragm Tables and Information

VERCO® Deck Diaphragm Capacity Tables with Strong-Drive® XM Medium-Head Metal Screws

  • Diaphragm tables for Verco's PLB-36 deck profile attached with Strong-Drive XM Medium-Head Metal Screws and Verco Sidelap Connection 2 (VSC2) using the PunchLok II Tool.
  • Diaphragm capacities are calculated based on Steel Deck Institute's Diaphragm Design Manual and have been confirmed with full-scale diaphragm testing.
  • Strong-Drive XM Medium-Head Metal Screws specifically designed for the narrow flutes of interlocking B deck profiles commonly found in the western US.

New Millennium Steel Decking Design Tools with
Strong-Drive X-Series Screws

  • Diaphragm Values with New Millennium Deck Profiles and Simpson Strong-Tie Fasteners (including XL and XU series screws).
  • Updated to the Steel Deck Institute's Diaphragm Design Manual, 4th Edition (to be referenced in 2018 IBC).

Steel Deck Information

Net Uplift
Enter applicable wind uplift pressure in psf. For shear only tables, do not enter a value. Net uplift is considered in the same format as the selected “Load values in”. For example, if “Load Values In” is selected as “ASD Wind”, then the “Net Uplift” load entered is also considered as “ASD Wind” load. Similarly if the user selects “Load Values In” option as “Nominal”, then the “Net Uplift” load entered is also considered as “Nominal” load. For Combined Shear and Uplift, MWFRS level loads may be appropriate as the shear would be MWFRS level of force. For Components and Cladding, the uplift load can be checked independently without entering shear load.
psf
Deck Type
Select the type of steel deck panel to calculate diaphragm shear strength tables. 1.5" wide rib, narrow rib, intermediate rib and 3" deep rib deck profiles are available for roofs. These decks are bare decks with no fill. 9/16" form decks and composite decks are available for floor decks. Fill options are available for floor decks.
Deck Thickness

Enter the thickness of steel deck.

Gauge Thickness
28 0.0149 in 0.38 mm
26 0.0179 in 0.45 mm
24 0.0239 in 0.60 mm
22 0.0295 in 0.75 mm
20 0.0358 in 0.91 mm
18 0.0474 in 1.20 mm
16 0.0598 in 1.52 mm
Support Thickness

Enter the steel thickness of the support:

  • 18 Gauge = 0.0451"
  • 16 Gauge = 0.0566"
  • 14 Gauge = 0.0713"
  • 12 Gauge = 0.1017"
  • 1/8" = 0.125"
  • 3/16" = 0.1875"
  • 1/4" = 0.2500"
  • 3/8" = 0.3750"

For support thickness less than 0.125” high shear screws like XL and XM are not available. For optimum design select a support thickness greater than or equal to 0.125”

Minimum support steel strength assumed is Fy = 36 ksi, Fu = 50 ksi except 18 gauge steel where Fy = 33 ksi and Fu = 45 ksi.

There are no Support Fastener options available for the selected Deck Thickness and Support Thickness entered. Please modify the input or contact Simpson Strong-Tie for further assistance.

Strong-Drive Fastener Information

Support Fastener Options


Side-Lap Fastener
Load Values In
Diaphragm shear strength tables can be generated to report nominal, allowable (ASD) and strength level (LRFD) shear strengths. Allowable diaphragm shear strengths have the safety factor included in the tabulated values and strength level shear strengths include the relevant phi factor.
First Deck Span in Table
Enter the first deck span to be shown in the table. Tables are generated starting with the span selected and incremented in 0.5 ft Total of 10 deck spans are calculated in the table.
ft
  • Support Fastener Layout
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Calculation Results
Steel Deck
Diaphragm Calculator
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Support Fasteners:
Side-Lap Fasteners:

Click on a shear strength or K1 value in the table below to view and print specific calculations.

Table Notes

Nominal shear listed shall be used with the appropriate Φ or Ω factor and may also be limited by panel shear buckling (reference table below).
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Building Information

Project
Length, L
Enter the length of the zone. The information is used in selecting the optimized solution based on the cost index.
ft
Width, B
Enter the width of the zone. The information is used in selecting the optimized solution based on the cost index.
ft
Joist Spacing, p
The support steel spacing (of joists, beams) should be entered here.
ft

Load Information

The load type can be entered here. Two options are available:

  • Wind
  • Seismic
Diaphragm Shear

Enter the demand shear load acting in the zone. In case of ASD, enter service shear load and if LRFD is chosen enter factored shear load.

plf
Net Uplift

The net uplift load acting in the zone should be entered here. In case of ASD. enter service level load and in case of LRFD enter factored load.

The uplift load entered is used to determine the combined shear and tension interaction effects on the fasteners to determine the remaining diaphragm shear capacity; however, it is not used to design the deck itself.

psf

Steel Deck Information

Deck Type
The type of steel deck can be chosen here. The Steel Roof Deck has typical roof deck profiles and deep decks. The Floor Deck has Composite decks and Non-Composite (form) decks.

Deck Panel

The type of deck panel can be selected here.

For Steel Roof Deck B, F, A and N decks are available:

  • B = WR (Wide Rib)
  • F = IR (Intermediate Rib)
  • A = NR (Narrow Rib)
  • N = DR (Deep Rib)

For floor decks, form deck and composite decks are available to choose from.

Deck Properties
Edit Deck Properties
Fill Type

The type of fill material can be selected here. The available fill options for each type of deck are:

Steel Roof Decks

  • No Fill

Non-Composite Floor Decks

  • No Fill (Bare Deck)
  • Type I Insulating Fill, fc' = 125 psi
  • Type II Insulating Fill, fc' = 125 psi
  • Light Weight Concrete, fc' = 3000 psi
  • Normal Weight Concrete, fc' = 3000 psi

Composite Floor Decks

  • No Fill (Bare Deck)
  • Light Weight Concrete, fc' = 3000 psi
  • Normal Weight Concrete, fc' = 3000 psi
Panel Width

The panel width for the selected deck can be chosen here. Choose a particular width that is available for the deck selected or choose 'any panel width' option to get all options.

1.5 B, F, A Decks

  • 36" panel width
  • 30" panel width
  • Any panel width: Includes all panel widths in design.

3 N Decks

  • 24" panel width

Form Decks

  • 35" panel width
  • 30" panel width
  • Any panel width: Includes all panel widths in design.

Composite Decks

  • 36" panel width
Deck Thickness

Select the thickness of the steel deck here. Select "Optimize" to allow the program to design the minimum thickness of the steel deck for a given diaphragm shear and uplift. The diaphragm shear capacity is determined in accordance with SDI Diaphragm Design Manual DDM03.

Please Note:

Deck thickness does not consider gravity or vertical loads such as but not limited to dead and live loads on the deck, suspended loads such as ceilings, light fixtures, ducts or other utilities, construction and maintenance loads or cantilever loads. Gravity and all other load cases shall be the responsibility of the building designer.

  • 28 Gauge = 0.0149"
  • 26 Gauge = 0.0179"
  • 24 Gauge = 0.0239"
  • 22 Gauge = 0.0295"
  • 20 Gauge = 0.0358"
  • 18 Gauge = 0.0474"
  • 16 Gauge = 0.0598"
Support Steel Thickness

Enter the steel thickness of the support:

  • 18 Gauge = 0.0451"
  • 16 Gauge = 0.0566"
  • 14 Gauge = 0.0713"
  • 12 Gauge = 0.1017"
  • 1/8" = 0.125"
  • 3/16" = 0.1875"
  • 1/4" = 0.2500"
  • 3/8" = 0.3750"

For support thickness less than 0.125” high shear screws like XL and XM are not available. For optimum design select a support thickness greater than or equal to 0.125”

Minimum support steel strength assumed is Fy = 36 ksi, Fu = 50 ksi except 18 gauge steel where Fy = 33 ksi and Fu = 45 ksi.


Fastener Information

Structural Fastener Inputs

Structural Fastener
Corrosion Resistance

Simpson Strong-Tie fasteners are available with bright-blue zinc coating or Quik Guard® coating

  • Bright-blue zinc coating provides a low level of Corrosion Resistance. In the ASTM B117 salt spray test it provides 36 hours of protection before the appearance of red rust.
  • Quik Guard is a proprietary double-barrier coating that consists of an electrodeposited base layer with an organic paint layer. In the ASTM B117 salt spray test Quik Guard has an average 1.9% red rust at 1,000 hours of exposure. This coating provides a medium level of Corrosion resistance.
Structural Screw
Optimized Solutions

This option provides the most optimized solution based on the cost. It will run the options for various Simpson Strong-Tie fasteners and provides the three lowest cost options with the model number of structural fastener/model number of side-lap fastener and the structural pattern and number of side-lap fasteners.

Model Number

Side-Lap Fastener Inputs

Side-Lap Fastener
Corrosion Resistance

Simpson Strong-Tie fasteners are available with bright-blue zinc coating or Quik Guard® coating

  • Bright-blue zinc coating provides a low level of Corrosion Resistance. In the ASTM B117 salt spray test it provides 36 hours of protection before the appearance of red rust.
  • Quik Guard is a proprietary double-barrier coating that consists of an electrodeposited base layer with an organic paint layer. In the ASTM B117 salt spray test Quik Guard has an average 1.9% red rust at 1,000 hours of exposure. This coating provides a medium level of Corrosion resistance.
Side-Lap Screw
Number of Side-Lap Fasteners
Edit Range
Model Number
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