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Tracing The Load Path

The sculpture is known as “Spot” and it marks the entrance to the newest building on the NYU/Langone Hospital campus, facing 34th Street between First Avenue and the East River. I assume that the mask was added to the dog’s face sometime during the Covid lockdown this past spring. I had the same reaction to it that most people do: it’s amusing and a pleasant break from the regular streetscape.

Bu then I started looking closer. The outside of the dog part of the sculpture is fiberglass, and there’s no way that an ordinary thin shell of that material would be strong enough to support the weight of even a hollow fake car. So there’s obviously some structure inside – almost certainly metal, maybe steel, maybe aluminum – and then the question becomes what it looks like. You can draw a straight line from the dog’s nose down to her hindquarters, so that’s one obvious location for a support. If that’s the only support, then it would have to be fixed at the base so that fit can’t rotate, to enable resistance against wind load and overturning from the fact that the gravity load of the car isn’t directly vertical over the base of that line. Providing a single foundation that’s fixed against rotation is possible but annoying.

On the other hand, maybe the structure actually follows the basic structure of a dog, and there are a pair of supports in the front legs, straight lines from the front paws that join the other support somewhere in the upper torso. That would make the three supports into a tripod, which gets rid of the need for rotational fixity – the forces at the base of the three supports will be sideways push (easily restrained by the foundations pressing on the soil), downwards push (ditto), or upwards pull (resisted by the dead weight of the foundation). This is more complicated metal work, but it makes the analysis and the construction of the foundation much, much simpler.

Finally, it’s possible that the interior frame ends at the front grille of the car, and the car’s own rigidity is used to keep it upright, but I doubt it. That would require a complicated connection to properly transfer the bending moments from the car to the frame inside the dog’s nose. It’s much easier to simply extend (with a bend in the line) the dog’s frame up into the car.

Maybe I’ve gone too far, but at least it wasn’t pizza this time.