Influence of lightweight structural design of office buildings on vibration levels due to people walking and operation of mechanical equipment

Abstract

West coast buildings typically use lightweight structural designs, even for Class A office building. This means the best floors use lightweight concrete on fluted decks with beam and column spacings of 30 to 35 ft. with open web joists at 10 ft. on center. Class B office building may use columns at 28 and 35 ft. with only two‐layers of plywood on wood open web joists at 24 in. on center. The resulting floor/ceiling assemblies are structurally sound but dynamically very live. Some structural damping would be expected from the introduction of partitions, but with the use of large open areas and partial height partitions, damping is limited. These assemblies have relatively low resonance frequencies and are very susceptible to any sinusoidal input force such as people walking or operation of mechanical equipment. Vibration measurements, made on four buildings after complaints were received, show the source of some of these problems. The results are compared with predictions by Murray et al. and Ungar et al. ...