Vibration analysis of waffle floors

Abstract

Two-way grillage or waffle floors are used extensively in semiconductor factories as they provide high impedance mounts for manufacturing equipment that is extremely vibration sensitive. This paper presents a mathematical model for the analysis of vibration at the center of a bay and the transmission of vibration along a waffle floor. The mathematical model is compared with finite element models and experimental results from several manufacturing buildings, and shows good agreement. Trends are shown for the displacement and resonance frequency of the floor as the thickness of the floor, size of the bays and the stiffness of the columns are varied.