Damping ratio identification of a volumetric modular high-rise building

Abstract

Modular Construction is a rapidly growing construction method being employed in increasingly taller and more slender structures. As this innovative form of construction reaches new heights, it is important to understand the inherent properties which govern the dynamic response. The damping ratio of a structure is a critical value in determining the acceleration response of a building and is best characterised through in-situ monitoring. However, there are very limited reports of the damping ratios from modular buildings, resulting in a significant uncertainty in the dynamic response of this form of structure. This paper reports research performed through in situ monitoring of a high-rise modular building, College Road, located in Croydon, London, United Kingdom. Details of the modular building and the monitoring set up are presented. The recorded acceleration responses of the structure are discussed and four different OMA methods, the Bayesian Fast Fourier Transform, Random Decrement Technique, Analytical Modal Decomposition Random Decrement Technique and Bootstrapped Analytical Modal Decomposition Random Decrement Technique, are applied in order to obtain estimates of modal properties. Both the Bayesian Fast Fourier Transform and Bootstrapped Analytical Modal Decomposition Random Decrement Technique methods allow for estimates of the uncertainty of the calculated damping ratios, providing greater insight into the dynamic behaviour and the range of possible values. Mixture distributions are generated to account for inter-event variability and allow for assessment of the probability of a damping ratio falling below a specified value. This research advances the limited knowledge surrounding the inherent properties of this new method of high-rise construction, enabling better prediction of the dynamic response and assessment of compliance to habitability requirements.