Today I started getting into the nitty gritty of how to stop a floor from vibrating. When dimensioning the floor slab of a building, one of the considerations is to check whether the natural frequency of the floor is in the same frequency range as that for footsteps. If the two frequencies do coincide the latter could resonate with the first causing the floor to shake.
Today I have been looking at an American document that brings together the different ways of estimation this interaction. Most of the results are based on empirical evidence of what seems to work. This lack of rigour is fine with me, and is common in engineering. The thing which has really held me up is the units: all the calculations are in pounds, feet and inches! Could there be a more unhelpful system of measurement?
Curious about this archaic standard, I started hunting around on Wikipdedia and found a wealth of information on the origins of both systems. Apparently, the only countries still to use imperial units of measurement are the USA, Liberia and Myanmar, although, I might add that here in the office my colleagues were surprised to here that in the UK we also use the metric system.
I urge anyone who is similarly disposed towards the imperial system, to use this site to help them out.