Dynamic loading on a prefabricated modular unit of a building during road transportation

Modular building construction is an emerging trend in the construction industry. During the course of road transportation of the modular unit of a building, vehicular vibrations on the truck-trailer may cause damage to components that are attached to the unit. The amount of dynamic loading depends on many parameters including the level of loading on the vehicle, location of the centre of mass, suspension setup of the truck-trailer, and amount of damping of the vibrating parts. The effects of these parameters on the vertical motion of the trailer-chassis are the focus of interest in this study. The acceleration response spectrum representing the filtering effects of the suspension system and that of the mounting can be calculated by modelling road roughness as a stationary Gaussian process, whereas the truck-trailer-trailer is represented as a 2D pitch-plane model. Parametric variations in the acceleration response spectra are presented in the compact form of peak value curves. An algebraic expression for calculation of the maximum spectral accelerations experienced by attachments to the unit is also presented. It is concluded at the end of the study that a component mounting should be designed to withstand a vertical acceleration of the component of up to 32m/s.(2) (or 3.3 g) in both directions in addition to gravitational acceleration. The design of mountings and their connections which satisfy this strength requirement can be deemed sufficiently robust to withstand vibration in the normal course of road transportation without the need for any further assessment. Less conservative predictions of the strength demand can be obtained using recommended algebraic expression or design charts provided in the paper.