Our Latest Online Resource: Steel Deck Diaphragm Calculator

Although Simpson Strong-Tie is best known for our structural products: engineered structural connectors, lateral systems, fasteners and fastening systems, anchoring products and most recently, concrete repair, protection and strengthening (RPS) systems, we are continually developing new and exciting software solutions. As we’ve discussed in prior blog posts, Simpson Strong-Tie has numerous software programs and web and mobile apps available for download or online use at www.strongtie.com/software. Today, I’d like to review our recently launched web app, the Steel Deck Diaphragm Calculator. The calculator is accessible from any web browser and doesn’t require downloading or installing special software.

While the method of designing and specifying a steel deck and its attachment can vary by region, most designers are familiar with the Steel Deck Institute (SDI) and its Diaphragm Design Manual, 3rd Edition (DDM03). DDM03 presents diaphragm shear strength and stiffness equations for various steel deck profiles and commonly used attachment types (welds, power-actuated fasteners, or screws). The calculations can be quite tedious, so the SDI has developed numerous tables using these equations and placed them at the back of DDM03 for easy reference.

Typical diaphragm shear table from SDI’s DDM03. Image credit: SDI.
Typical diaphragm shear table from SDI’s DDM03. Image credit: SDI.

Since the tables in DDM03 are based solely on the fasteners and deck profiles included, determining diaphragm capacities utilizing any other proprietary fastener or deck profile fall on the designer or the proprietary product’s manufacturer. Enter Simpson Strong-Tie.

Our Steel Deck Diaphragm Calculator enables users to produce custom diaphragm tables similar to those in DDM03, generate detailed calculations using SDI equations based on project-specific inputs, as well as optimize deck fastening systems to ensure the most cost-effective design is utilized. The calculator incorporates our X-series steel decking screws, including the recently launched Strong-Drive® XL Large-Head Metal Screw, which has one of the highest capacities in the industry and in most cases, can be used as a 1-for-1 replacement of pins or 5/8 diameter puddle welds. (For additional information comparing Simpson Strong-Tie X-series and XL screws to pins or welds, review F-Q- STLDECK14.)

Decide whether to optimize a design or generate diaphragm tables.
Decide whether to optimize a design or generate diaphragm tables.

The app can be used with minimal required input to generate tables and project-specific calculations. A more detailed analysis can be performed by inputting parameters for up to five unique zones, including overall dimensions, diaphragm shear, joist spacing, uplift and more.

Input detailed information for up to 5 different zones on the same project.
Input detailed information for up to 5 different zones on the same project.

One unfortunate aspect of many web apps is that your work is typically lost once you close your web browser. I’m happy to report that the folks here in our app development group have added the ability to save and upload project files. The calculator also provides a clean PDF printout of your results while giving you the option to generate a submittal package with supporting documentation, such as code reports, product approvals and installation recommendations.

Generate a submittal that includes all calculations and necessary supporting documentation.
Generate a submittal that includes all calculations and necessary supporting documentation.

Try the revised Steel Deck Diaphragm Calculator yourself and let us know what you think. We always appreciate the feedback!

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Keith Cullum

Author: Keith Cullum

Keith is a Branch Engineer at Simpson Strong-Tie. After graduating with a degree in Architectural Engineering from Cal Poly San Luis Obispo, he worked for an engineering consulting firm in Southern CA designing commercial structures in steel, concrete and masonry, and multi- and single-family residential structures in cold-formed steel and wood. Prior to joining Simpson Strong-Tie in 2012, he worked for a steel deck manufacturer performing R&D and providing product technical support and promotion. He is a LEED Accredited Professional (AP) and a registered Professional Engineer in multiple states (CA, TX, OK, KS, MO, AL, AR, and MS).

3 thoughts on “Our Latest Online Resource: Steel Deck Diaphragm Calculator”

  1. A useful app, especially the multi-zone options. What would make it even better is if it were to include 29 and 26 ga wide rib panels (pole barn panels). To my knowledge there aren’t any calculators, and not many recently published tables for that.

    1. Although our web app does not currently include any of these deck profiles, the recently published AISI S310-13 “Standard for the Design of Profiled Steel Diaphragm Panels” does provide a method for determining the diaphragm shear strength and stiffness of any steel deck profile. This standard adopts and expands upon the equations presented in SDI’s DDM03 and also provides provisions for fastening steel deck to substrates other than steel (wood, concrete, etc). An electronic copy of AISI S310-13, along with several other AISI standards, can be downloaded free of charge from http://www.aisistandards.org.

    2. Although our web app does not currently include any of these deck profiles, the recently published AISI S310-13 “Standard for the Design of Profiled Steel Diaphragm Panels” does provide a method for determining the diaphragm shear strength and stiffness of any steel deck profile. This standard adopts and expands upon the equations presented in SDI’s DDM03 and also provides provisions for fastening steel deck to substrates other than steel (wood, concrete, etc). An electronic copy of AISI S310-13, along with several other AISI standards, can be downloaded free of charge from http://www.aisistandards.org.

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