More and more frequently, engineers who have never encountered a floor vibration problem with their designs are finding themselves searching for fixes. I have been involved with the floor vibration serviceability for over 30 years. For the first 28 years, I heard of perhaps one problem floor a year; now it's one a month and sometimes more. Why?First, the reason is not LRFD. Yes, LRFD results in lighter floors, especially if they are composite, but nearly identical designs can be obtained with ASD. The reasons are longer beam spans (40 ft today versus 25 ft a decade ago), less actual live loading (11 psf versus perhaps 25 psf), and less damping because of open office areas and less paper, heavy desks, and file cabinets. The bottom line is that floor vibration serviceability can control the design. We may have to accept the fact the may need to add steel to control the problem just like we do to control drift in high-rise buildings.
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