Structural Steel


Although a floor system may be adequately designed from a strength standpoint, a serviceability problem will result if unacceptable vibrations occur during normal usage of the floor.
The anticipated performance of the floor can be analyzed by computing the first natural frequency and the amplitude, that is, deflection when subjected to a heel-drop impact, of the floor framing member and plotting the result on a modified Reiher-Meister scale (Fig. 8.28) to determine the degree of perceptibility to vibrations. Generally, designs that approach or exceed the upper portion of the ‘‘distinctly perceptible’’ range should be avoided.

Various researchers have verified that the modified Reiher-Meister scale is accurate for predicting perceptibility to vibrations for concrete slab (including concrete fill on metal deck) floor systems framed with steel joists or steel beams.
(T. M. Murray, ‘‘Acceptability Criterion for Occupant-Induced Floor Vibrations,’’ AISC Engineering Journal, vol. 18, no. 2. T. M. Murray, D. E. Allen, E. E. Ungar, ‘‘Floor Vibrations Due to Human Activity,’’ AISC Steel Design Guide Series, no. 11.)
The systems used for floor framing (Arts. 8.8 to 8.14) can also be used for roof framing.
Other roof framing systems are described below.


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