Interview by Fred Schmidt
Today you will meet one of the structural engineers on the project. Designing the structure became a tag team affair as we worked through getting the project completed within the owner’s timeframe. Tom Bush, P.E., Ph.D. is a senior structural engineer at FSB. A pretty calm and easy-going guy but according the Cathleen he can toss back some serious snacks.
Tom, tell us about your role on the project?
Tom: I came in a little later in the project. A lot of the systems had been decided. I worked from the slabs down on the foundations. Checking wall strengths, detailing rebar, sizing the footings and designing the elevated floor system of the Gallery area over the mechanical crawl space; the slab on deck. The other thing was the lateral load system; the sheer walls and the elevator core and getting the foundations properly sized for those.
What’s the purpose of a sheer wall?
Tom: To help the building resist lateral loads. The gravity loads are the floor systems and the roof. Lateral loads are wind loads and seismic loads. I made sure the structure had adequate capacity to stand up to anything that may push it sideways.
What were some of the greater challenges from the perspective of designing the structural elements?
Tom: Part of it is that the Visitor Center is a very complex building; irregular shapes, high level finishes and doing a lot of work in a small space for a high-end facility. Some of the things we have to worry about with high finishes are systems like the elevated floor slab. Making sure with the large floor tile that we had adequate stiffness in the floor system so we would not have cracks. And the coordination with the other building disciplines particularly plumbing and mechanical including under floor systems like in the crawl space. Getting everything to fit into the spaces.
When you began to understand the project early on, what were some of your thoughts about the project?
Tom: I really didn’t know much about the project until I got into it. I had heard about it through the office that it was high-profile for a very important customer that we had worked with. Once you really get into it and see the details of what you have to fit in such a small space, it dawns on you, “there’s a lot in this building.”
Here’s the big career question. What led you down the path of becoming a structural engineer?
Tom: I had a family friend that was a civil engineer when I was in high school. I didn’t know what I wanted to do but knew I could handle math and science; I was interested in those kinds of things. Civil engineering you could do outside and I thought that’s the kind of engineer I wanted to be because I grew up on a farm, or working on a farm, so being able to do those kinds of things and then have the outdoor component. So, I took a path through undergraduate and graduate degrees, a little bit of academic background, and finally came to the practicing profession of structural engineering.
Where was that academic piece along the way?
Tom: I went straight through school. I got my graduate degrees, went straight into academics, straight from research and graduate level work into research and faculty work. Did some odd jobs, consulting, but not really a full-time practicing engineer.
So any other work before you settled here at FSB?
Tom: Just did some part-time work for consultants in the area. One of the things that I did do as a student is called a coop program, cooperative education program. So as an undergraduate, for about 3 years of my education, I alternated ¼ at school and ¼ working for a power company. So that field experience in civil engineering before I knew what civil engineers did was very valuable for my school experience.
So you went beyond the usual terminal degree (masters) for teaching.
Tom: Well, for academics in a research institution, it is a Ph.D.
What made you decide to take that extra step?
Tom: I really just enjoyed the technical aspects of structural engineering, learning structural engineering. The more I learned the more I knew I didn’t know. And that’s true today.
You know that’s really true for all of us.
Tom: Exactly, the more you learn the more you understand what you really don’t know. One of the most valuable things to that advanced degree to me is to fully understand what I don’t know and what I do know and to understand the differences. It can be a very humbling but very useful perspective.
Let’s talk about the approach to engineering this project. So from the beginning were you and Chris tag teaming it?
Tom: This particular project was different for us. Usually there is a lead engineer that gets involved very early in the process, early in the stages of design and follows the project all the way through. That was being accomplished by other engineers and so Chris and I toward the end of the project were pulled in to get more of the higher level, final production information into the project. Having a lot of work to do in a little bit of time I tend to gravitate more towards concrete and Chris tends to gravitate a little more towards steel. We both are structural engineers and can handle each one but that’s kind if where the split came about on this project.
On a side note, I understand that you have a few guitars around your house.
Tom: One or two, yes sir. Maybe 3 or 4 or 5 or 6. I enjoy that very much. It relieves stress, just a creative diversion. And I get to play at church. That’s a blessing too.
Well that’s a common thing we both have; enjoying music and being able to play at church. For me I like having that schedule of getting my guitar out every week. I didn’t used to always get my guitar out every week. But I like that. I like the discipline.
Tom: I’ve always played all the time. So there aren’t many times that I can remember where I didn’t have it out every week. But this gives a focus to it, a reason. Actually, now that’s about the only reason I do just to kick it around. Having a focus to it is very rewarding.
So you’ve been out to the job site on some occasions.
Tom: Just once so far.
But there was a specific challenge at the site when you went out there. It was a problem solving trip essentially.
Tom: Yes. With the ground water and trying to get the building pad in a situation where we could structurally start building on it. And it went through an iteration or two before the solution was finally reached. But it sounds like from what I hear from Lowe that they are moving very fast now.
I guess there was that first attempt working with the geotechnical engineer to find ways to deal with the water saturated soil. We were mashing 3″ rock into the ground trying to get it to stabilize in some fashion.
Tom: Yes, what you often called surge rock, trying to push the rock down to stabilize the soil but it kept disappearing from what I understand.
Yea, I wrote a previous post about how it was like chocolate pudding. But once they got the wet soil out and established the French drain it finally dried the soil to where they could get moving on.
Tom: Yes, it was effective enough to where they could get rebar down and work footings as fast as they could go. Generating a lot of questions, a lot of inspections going on. So, there’s a lot of progress going on.
You mentioned some RFI’s (a “Request for Information” is a formal documentation of a question from the construction team to the design team and allows for tracking of the questions and responses). What are some of the questions that have come up?
Tom: Questions involved with placement of water stop in the cold joints between the footings and walls because of some of the changes in the direction of construction and modifications to construction. Some of the walls got thinner, the water stop is a swell type material, a bentonite material and you must have adequate concrete thickness or the swelling pressures of the bentonite can pop the concrete. You’ve got to have enough concrete around the swell stop so that it works properly. So changes’ involving some smaller water stops. Just lots of details that come up from the inspection on the job site and just the day-to-day questions that come up in trying to take what’s on a piece of paper, the contract documents, the intent documents to the submittal documents which again that’s a whole lot closer to what’s going to be built. But until it’s in the ground, until the hands tie the rebar and they find out that this needs to go there and this piece of pipe has to be accommodated and all the discipline coordination questions that go with it. It’s about fully understanding and seeing what’s being built on the site. It just introduces questions. It’s hard to think through everything possible that can happen.
I often explain to friends that are not familiar with the design-construction industry, but also to clients that this is pretty challenging because in what we do every building is a prototype; each one is one of a kind. It’s not like the car industry where you don’t buy a car the first year they make it because they’re working out the bugs, but the second year it should be just fine. We don’t have that luxury. So we have to work out the bugs as we go and it’s a challenge.
Tom: That’s a good analogy. It’s always a challenge to work through everything you can in the time you have allotted with all the coordination and trying to think things through. Even on well coordinated jobs, just the physical process of getting pipe “a” and pipe “b” and rebar ”c” into the space and getting everything not to hit is challenging. Working through issues is a reality.
Well we covered a lot of ground, I appreciate it.
Tom: It was a pleasure