Vibration of Heavy Industrial Slabs

The theory of vibration of homogeneous, isotropic plates is well developed. For concrete slabs, however, accurately predicting vibrational characteristics is difficult because of uncertainty as to material properties and the degree of cracking that will occur. In addition, the idealized boundary conditions are seldom realized in practice. Because of the difficulty in accurately predicting the natural frequencies of concrete structural elements, there was a need for a simple, yet accurate, method for experimentally determining dynamic responses. The testing apparatus described in this note was assembled to satisfy that need. This note examines the testing apparatus for determining the natural frequencies of stiff structural components. Its advantages include simplicity and ready availability of the test components. Data can be obtained quickly and inexpensively, yet with accuracy. The method has been used for about 2 yr for various applications (floor systems and column support systems for heavy machinery). Results have been entirely satisfactory.