Finite-Element Modeling and Parametric Study of Glulam Beam-and-Deck Floors

Abstract

Small-amplitude cyclic vertical motions of timber floors perceived as unacceptable by humans are commonly the result of walking impact forces. Contemporary vibration serviceability guidelines mainly require prediction of static displacement and modal frequencies of floors. This study used an advanced finite-element (FE) analysis approach to model glulam beam-and-deck floor systems. This permits prediction of static displacement and modal response characteristics that closely match values determined by testing full-scale floor. The verified modeling method is used to show how variations in floor details such as span and floor width affect the vibration behaviors of these floors. This shows that changing the floor width has little effect on the fundamental frequency and midspan deflection of a floor, but higher-order modal frequencies are strongly affected. Although fundamental frequency of floors is not highly sensitive to the flexural rigidities of decking layers, higher-order modes are strongly affected. The broad conclusion is that reliable prediction of parameters engineers used to predict vibration serviceability of such floors depends on the use of appropriate models. Appropriate models are ones that incorporate deep system effects on motions stemming from the layered nature of beam-and-deck element floors and depths of glulam elements used as the beams.