Get There Quicker! How CFS Designer Can Help Speed Up Your Design Process

Did you know that Simpson Strong-Tie is celebrating its 60th birthday this year? We started out with one punch press and the ability to bend light-gauge steel. Then, one Sunday evening in the summer of 1956, Barclay Simpson’s doorbell rang and a request for our first joist hanger led us into the wood connector business. Since then, we’ve continued to grow that business by focusing on our engineering, research and development efforts. Some might say that nowadays we’re an engineering company that also happens to manufacture products, as evidenced by our focus on developing technology tools over the past few years such as web calculators, an updated website and design software. Our focus on technology, however, is really another aspect of our continued commitment to excellence in manufacturing and our application of the tenets of lean manufacturing.

Many of you may already be familiar with the idea of lean manufacturing made famous by Toyota in the early 2000s, along with the principles of continual improvement and respect for people. The concept of continual improvement is based on the idea that you can always make small changes to improve your processes and products. Although they were established in a manufacturing setting, these ideals ring very true for engineering as well; eliminate steps in your design process that don’t add any value to the final project and always be on the lookout for tools or techniques that can speed up your process. Thinking lean isn’t about cutting corners to get your result faster, it’s about mindfully getting rid of the steps that aren’t helping you and finding better ways of doing everyday tasks.

As structural engineers, we can find ourselves working on a variety of projects that lead us to perform repetitive calculations to check different conditions, such as varying parapet heights on the exterior of a building, or we may find ourselves working with an unfamiliar material, such as light-gauge or cold-formed steel (CFS), where we have to take some time away from design to review reference materials such as AISI S200-12 North American Standard for Cold-Formed Steel Framing. Wouldn’t it be great if there were a design tool that could help you complete your light-gauge projects more quickly, in complete compliance with current building codes?

It turns out that Simpson Strong-Tie offers a design tool called CFS Designer™ to help structural engineers improve their project design flow. This program gives engineers the ability to design light-gauge stud and track members with complex beam loading and span conditions according to building code specifications. What does that actually mean, though? Allow me to illustrate with an example of a design project.

Let’s say you’re designing a building and part of your scope is the exterior wall framing, or “skin” of the building. You probably get sent some architectural plans that look something like this:

Figure 1. Sample building elevation with section marks.

Figure 1. Sample building elevation with section marks.

The architectural elevations will have wall section marks indicated for different framing situations. Two sample wall sections are shown in Figure 2.

Figure 2. Sample building wall sections.

Figure 2. Sample building wall sections.

This building has several different wall section types that include door and window locations, varying parapet heights, diverse finish materials that need to meet different deflection criteria, and different connection points back to the base building. The traditional design calculation that you would need to run for one wall section might begin with a loading diagram similar to Figure 3 below.

Figure 3. Sample calculation of wall stud loading diagram.

Figure 3. Sample calculation of wall stud loading diagram.

Once you have your loading diagram generated, you would need to use reference load tables or a computer analysis program to solve for the axial and moment demands, the reactions at the pinned supports, and the member deflections. 

After you determine the demand loads, you would then need to select a CFS member with sufficient properties, and you may need to iterate a few times to find a solution that meets the load and deflection parameters. After you’ve selected a member with the right width, gauge and steel strength, you’ll need to select an angle clip that can handle the demand loads, as well as fasteners to connect the clip to the CFS stud and to the base building. You would also need to also check the member design to ensure that it complies with bridging or bracing requirements per AISI. Then, after all that, you’d have to repeat the process again for all of the wall section types for your project.

Figure 4. Hmm, CFS design would sure be a lot easier if buildings were just huge windowless boxes…

Figure 4. Hmm, CFS design would sure be a lot easier if buildings were just huge windowless boxes…

Just writing out that whole process took some time, and you can imagine that actually running the calculations takes quite a bit longer. I think we can all agree that the design process we’ve outlined is time-consuming, and here’s where using CFS Designer™ to streamline your design process can really help.

CFS Designer is a structural engineering design program that can automate many of the manual steps that are required in the design process. It has an easy-to-understand graphical user interface that allows you to input your project parameters within a variety of design modules from walls and beams, jambs and headers, X-brace walls, shearwalls, floor joists, and roof rafters. The program also enables the design of single stud or track members, built-up box-sections, back-to-back sections, and nested stud or track sections. Figure 5 shows an example of how you would input the same stud we looked at before into the program.

Figure 5. CFS Designer™ user interface for wall stud design.

Figure 5. CFS Designer™ user interface for wall stud design.

The program will generate the loading diagrams and complete calculation package for all of these different situations. And along with checking the member properties and deflection limits, CFS Designer will also check bridging and bracing requirements and provide connector solutions for the studs using tested and code-listed Simpson Strong-Tie products. Figure 6 shows an example of the summary output you would receive.

Figure 6. The comprehensive summary output page that covers the complete member design down to the bracing and connection solutions.

Figure 6. The comprehensive summary output page that covers the complete member design down to the bracing and connection solutions.

One unique part of the output is toward the center of the second page, under the heading “Simpson Strong-Tie Connectors.” This section summarizes the tension and compression loads at each reaction point and then shows a connector solution (such as the SCB45.5) along with the number of screws to the stud and the number of #12 sheet-metal screws to anchor back to the base building. Simpson Strong-Tie has developed and tested a full array of connectors specifically for CFS curtain-wall construction as well as for interior tenant improvement framing, which allows designers to select a connection clip straight out of a catalog without needing to calculate their own designs per the code. It’s just another way we’re helping you to get a little leaner!

speed7

Figure 7. A typical SCB/MSCB bypass framing slide-clip connector showing directional loading along with the table of allowable connector loads.

Figure 7. A typical SCB/MSCB bypass framing slide-clip connector showing directional loading along with the table of allowable connector loads.

The last part of the output shown in Figure 6 is titled “Simpson Strong-Tie Wall Stud Bridging Connectors.” It checks the bridging and bracing requirements per AISI S100 and selects a SUBH bridging connector, an innovative bridging solution developed by Simpson Strong-Tie that snaps into place and achieves design loads while only requiring one #10 screw to connect for 75% of applications.

Figure 8. A close-up of the SUBH installed (left) and a wall of studs with bridging installed using the LSUBH clips (right).

Figure 8. A close-up of the SUBH installed (left) and a wall of studs with bridging installed using the LSUBH clips (right).

You can download a free trial of CFS Designer™ and give it a test drive to see how much time it can save you on a design project. The trial version has almost full functionality, with the exception of not being able to print the output sheets. You can see purchasing information online, and you should always feel free to contact your local Simpson Strong-Tie engineering department with any questions you may have. I hope you are able to take advantage of this great tool to further improve your everyday design processes. We will be sure to keep you updated on our latest technology tools that help speed up the design process.  If you’re using CFS Designer, we’d like to hear your thoughts about the program. Please share them in the comments below.