Dynamic load model for fork-lift trucks

Long-span warehouse floors can suffer problematic vibrations due to dynamic interaction with moving fork-lift trucks. However, the dynamic loads caused by trucks are poorly understood and no mathematical model of these loads suitable for use in a dynamic analysis has previously been proposed. This paper presents a two-degree-of-freedom dynamic load model of a fork-lift truck suitable for use in an analytical floor vibration assessment. The load model comprises two time-varying vertical forces that are a fixed distance apart. Each force is the product of a mass matrix and a vertical acceleration vector, which is in turn a function of the horizontal velocity of the truck. The model derivation is partly analytical and partly experimental, with some key parameters derived from field tests on four fork-lift trucks in a total of twelve configurations. Data for general models are presented for a range of truck capacities from 1000 kg to 6000 kg. The model fills a significant gap in the current state of the art of vibration analysis, enabling a realistic assessment of fork-lift truck-induced floor vibrations to be performed using a finite-element program.