Structural Engineering of Art Installation

[RickyTickyTavi]

I have an odd question.

The framing consisted of basically new 4 HSS beams, attaching to the existing structure, and connecting to a new HSS column which is supported by a new small foundation. The gravity loads are like 3-4 kips tops on the column. In between the HSS beams, I have cold formed light gage steel for the artist to make his attachments.

The art itself, are these panels 4'x4' aluminum or galv steel, wherein the artist has strung galvanized wire between he frames and threaded glass or plastic colored/translucent 1'' diameter beads between the frames. Theres a very tight spacing on it, so that when all the panels are put up, its creates an image which can be seen from the street.

The GC is about to file for permitting and they keep requesting I sign and seal the art itself, which I'm uncomfortable with. Theres not really a way for me to analyze wind acting on a tension wire with beads on it. The attachment is basically wrapping the wire around the 4'x4' frames. I stated that I recommend they speak the city and that I have my doubts that the city would require structural engineering on an art piece aside from its framing and support. Is anyone aware of any code references in IBC or elsewhere that discuss art pieces specifically?

 

[BridgeSmith]

I'm not at all familiar with the IBC or your local codes, but for the work I do (structural design for a DOT), a structure that doesn't present a substantial danger to the lives or safety of the public doesn't require a stamped design. Don't know if that's an argument you can make, but that's the approach I would take if presented something like that.

The other approach is to simply tell them you didn't design anything but the frame work, so that's all you can take responsibility for without reviewing the design of the other components. That would constitute a change in the scope of design services, right? So, they'd have to pay you for that, would they not?

 

[Canuck65]

I have done the engineering for a lot of art installations. Generally the City wants some form of assurance that whatever is installed will be safe, which I think is reasonable. Normally this defers to a structural engineer. Sculptures can be complex, typically not your standard footing/column/beam type project. If you are looking at the wire, you are going to have to come up with some form of loading scenario that you can then put numbers to, i.e. what would be a conservative assumption for wind loading (maybe a 1 ft. trib. width?)?? what would be a conservative assumption for the dead load of the beads??? See how that compares to the capacity of the wire. I am guessing you will have a pretty good capacity in the wire as long as it is a reasonably sized wire and if not, ask for that component to be upgraded. You can get some very high capacities in reasonably small wire. Then think outside the box, would the wire support a 200lb person who stepped on the wire while climbing the sculpture ... it happens. You don't necessarily need to design for this scenario, nor do you need to tell everyone you designed for this scenario, just good to run through the confirmation on your own. You need to go back to engineering basics, use judgement, and be conservative where appropriate. There are no code references that I know of that deal with art installations. FEM comes in handy on some projects.

 

[BridgeSmith]

For the loading on the wire in particular, you should be able to analyze it as a catenary span, such as a span wire traffic signal structure, only on a smaller scale. The method we use can be found in Appendix A of any edition of the AASHTO Sign spec.

 

[RickyTickyTavi]

Thanks HotRod and Canuck, My local IBC code amendments had a exemption listed for "works of art" that I was able to use. But I have tagged that location in Appendix A of my AASHTO for future reference. My main worry wasnt so much the pure tension of the wire, but rather the connection to the frame which is basically wrapped around it a few times. I had no idea if the artist was consistent in his construction of the wire connections, etc. That partly lead to my discomfort of signing and sealing the art piece specifically. We were discussing possibly load testing the art panels as a method of affirming their capacity.