CSES Engineering solved the problem by stiffening main structural members.

100_1083This is a really unusual project. For privacy, I have not shown the front of the house. It is a sorority house, and CSES Engineering was called to solve a problem. It seems that one of their rituals involves over 100 sorority sisters in one room, jumping up and down in unison. The house mother was concerned because she noticed, no surprise, some rather large vertical deflections of the floor during this activity, reportedly two or three inches.

100_1081So in cooperation with a contractor and architect, CSES investigated the framing. It turned out that the framing was, in fact, more than adequate for normal usage, and the floor was solid and well built for most purposes. The jumping in unison set up a resonance, in which each jump coincided with the deflection from the previous jump, and made it a little larger. This effect was combined with what is called an Impact effect – that is if a 120 pound girl jumps up two feet, the force she hits with on the way down is much greater than 120 pounds.

100_1079CSES Engineering solved the problem by stiffening a couple of the main structural members, adding new members, and adding glued and screwed joints to create some additional damping of the system. All a bit technical in the calculations, but the resulting structure performed far better.

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