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!

Steel Roof Decking

My wife, Kristin, sometimes gets angry with me while grocery shopping. It’s understandable. She’s asked me to grab some tomatoes or a loaf of bread and instead I’m just standing there looking up at the ceiling. Technically, it’s not a ceiling, but the underside of the roof, and I’m looking up to see the connection detailing, including whether or not the steel roof deck I’m looking at was welded, pinned, or screwed down to the steel joist, beam and angle supports.

If you’re a structural engineer, you might also do this inside your local supermarket, Target, Walmart or The Home Depot. Many of these “big box” stores are typically constructed of tilt-up concrete perimeter walls, tube steel interior columns, and roofs built of steel joists, girders and decking. Though Simpson Strong-Tie is well known in the light-frame wood construction industry, some may not know that we’ve long been developing and selling anchors and fasteners for commercial construction.

Outside of a few dips into a Verco or ASC steel decking catalog from my consulting days in Las Vegas, my first real foray into the steel decking industry was about two years ago. I was asked to assist in representing Simpson Strong-Tie as an associate member at the Steel Deck Institute’s (SDI) quarterly meeting held just down the road in Dallas in November 2011. Since joining SDI, my main focus has been to find out what the industry needs, both from the installer’s and designer’s standpoint for steel deck attachment. Though we’ve had a screw attachment offering for years, my colleagues and I have worked to develop a better overall system which now includes:

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