How Diverse Job Experience Aids HSS and Limits of Applicability

Peer Perspective: Craig Haas, P.E. and President of Haas Engineering

From the Guthrie Theater in Minneapolis to feed facilities in Gainesville, Craig Haas, P.E. and president of Haas Engineering, has expertise that lends itself to a variety of projects. Read further to hear his perspective on HSS limits of applicability, the advantages to using HSS and his career path within the steel industry.

Q: Can you introduce yourself and tell us more about your current professional role?

A: My name is Craig Haas. I’m currently the president and CEO of Haas Engineering, a firm I established in 2017. I also work quite a bit as a contract employee for Meyer Borgman Johnson out of Minneapolis. I’ve been involved with the Structural Engineers Association of Iowa as a volunteer, and I’m the vice president of the Iowa chapter of the American Parkinson Disease Association.

Haas has worked in firms of various sizes on jobs including connection design and steel fabrication. Some of his career highlights include the Egger Steel Company, LeJeune Steel Company, Van Sickle Allen & Associates, Ericksen Roed & Associates, and Moeller Engineering. Haas says it was during his time at Ericksen Roed & Associates that he realized he couldn’t just be an engineer — he needed to be a businessman. Entrepreneurship would help sell clients his ideas and achieve long-term success.

Q: Over the span of your career, what has been the most interesting steel connection design project you’ve worked on?

A: The project that really took a leap forward in my ability to not only do connection design but also sell pretty good-sized projects to clients was for the Guthrie Theater in Minneapolis. It has a 175-foot cantilever bridge off the side of the building that extends toward the river. The bridge has 7,000 kips of tension in the top chord and 7,000 kips of compression in the bottom chord.

It was bigger than anything I had done up to that point. And the cantilever was just one of the challenges. There’s also a yellow box off the side of one of the walls that’s a glass atrium. The deflection limits on the wall were very stringent to support the box there without glass panels leaking.

Q: Your extensive steel design experience spans over many projects, from big buildings in urban areas to rural agricultural facilities. What are some challenging differences between these extremes in terms of overall design of the structure and connections?

A: One of the big differences is that agricultural facilities aren’t really as much buildings as they are large groups of equipment that are stacked on top of one another. And that’s how you have to think about them in the design.

Buildings where people spend lots of time have floor and roof diaphragms. You can tie the bracing to those and make them relatively stiff. In agricultural facilities, you often don’t have floors or roofs. So, you don’t have the ability to take a floor plate and tie everything to it and make the structure stiff. You spend a lot more time tracking load paths. Since you’re dealing with large, heavy pieces of equipment that shake, you have to account for the dynamic loading impact on the structure.

Haas explains that since agricultural facilities are typically built in rural areas, they don’t have as much oversight from building or code officials as structures in cities. This is something designers and engineers should be conscious of when they work on rural structures.

Q: You have a unique perspective as someone who has worked in engineering firms of all different sizes and at steel fabrication companies. Across the board, in what types of structures are HSS most challenging to work with?

A: HSS sections are more challenging to connect with moment and rigid connections because the wide flanges have an advantage. The flanges are where the concentrated force couple is located. It’s easier to transfer the force couple from a wide flange section to a column or another beam. In HSS, it’s a little different. You’ve got a four-sided member as opposed to an I-shaped member.

Haas expresses that HSS are underutilized in agricultural facilities. Square HSS have equal stiffness and strength in both directions — which becomes an advantage because agricultural facilities often use elevated bins. If a bin is on a stand with a wide flange section, there will be strong and weak axes on the columns. The designer will have to account for bracing on the weak axis. Since square HSS sections have equal stiffness in both directions, there’s no need for much bracing. This makes it easier to flow truck traffic underneath the elevated bins.

Also, HSS tend to be cleaner. I had a feed mill in Gainesville, Florida, that had a collapse. I was called to investigate and help rebuild the facility. The bins were sitting on wide flange sections and rotten corn was sitting on the top portion of the bottom flange. The corn had rusted the web of the W-section all the way through, and a huge section of the web was disconnected from the bottom flange. This caused a failure of the section and the collapse of the bin.

If you use an HSS member instead of a wide flange section, you won’t have anywhere for that corn to sit and collect. Keeping the facility clean is a big advantage that HSS sections have over wide flange sections.

Q: Could you describe a time where the limits of applicability challenged a project you worked on? Was the project revised to better suit the connections or did you need to use rational analysis to make the connections work?

A: When I worked at Meyer Borgman Johnson, we had a project at Disney World in Orlando, Florida, for a new ride. It had a roof that was curved — a space frame with no flat plane in it. We were doing the erection engineering, so we designed the connections in the shoring and the connections of the temporary shores to the roof.

There were a lot of tubes and unique forces that the tubes worked relatively well for. Some of the tubes, though, had restrictive limits of applicability. So we added stiffeners and other things to the faces or, in some cases, bumped up the tube size so they fell within the prescriptive limits of applicability.

Q: Sometimes, limits of applicability cause problems that lead to adapting design plans. Similarly, health issues can provide limits to the career of design professionals or cause career paths to change. I understand you’ve dealt with these challenges yourself. Can you please elaborate on your situation and offer any advice to other design professionals who may be in a similar position?

A: In October of 2015 at the age of 45, I was diagnosed with Parkinson’s disease. The more traditional Parkinson’s patients are diagnosed in their 60s or 70s. They’re much closer to retirement or are retired already. The kids are probably off to college or independent. I had young children.

My neurologist told me I needed to minimize stress and couldn’t work long hours. So, I worked with the owner of Moeller Engineering to unload some of my responsibilities. It was difficult because I was a go-to person and provided structure to the office. Later in 2017, I left to start my own firm. [Being my own boss] allows me to control my own hours and stress.

For other design professionals who may be in a similar situation, I’d say just because you have Parkinson’s disease doesn’t mean you can’t enjoy life. One piece of advice I have for anybody, not just other design professionals, is that brain health and physical health are one in the same. The better the cardiovascular shape you’re in, the better off your brain health will be.

Q: What is one thing about designing structures or steel connections you wish future engineers understood?

A: I wish future engineers understood that it’s not just about the calculations or the numbers. You’re an important part of the design process. Your end goal is not to have a whole thick packet of calculations. Your end goal is to have a building. And you’ve clearly communicated everything the contractor needs to build that structure.

It’s important to take a step back and look at it as a whole. You need to understand how that building is going to function, where that building is supported, where the lateral structural system is, how the load paths get to that system, and more.

A fundamental skill of engineering is learning to use calculations to check the strengths and members. But you need to do so with the end goal in mind: putting together a constructible design within time frame constraints.