Dynamic behaviour and serviceability performance of long-span CLT band-beam floor systems: Full-scale experimental study

For the numerous characteristics that make cross-laminated timber (CLT) attractive to designers, such as its low density and high strength-to-weight ratio, they also contribute to increased sensitivity to low-frequency vibrations. CLT band-beams (BBs) offer a potential solution by reducing floor thicknesses, minimising supporting beam depths, and enabling longer spans (>8 m). This study experimentally investigates the dynamic behaviour and vibration serviceability of long-span CLT BB floor systems using a 9 m × 9 m laboratory floor comprising two CLT panel thicknesses and up to four BBs. The influence of BB span, CLT span, CLT thickness, screw connection density and inclination, and asymmetric superimposed dead load was investigated. Experimental modal analysis and controlled walking tests (1.4–2.1 Hz) were used to evaluate modal properties and vibration response in terms of weighted acceleration and vibration dose value (VDV). BB span was found to govern both modal behaviour and walking-induced response, whereas CLT span had a secondary influence. Increasing connection density enhanced stiffness but reduced damping, while screw inclination had only a minor effect. The inclusion of resilient material increased Mode 1 damping by approximately 30–35%. All measured VDVs remained below 0.22 m·s⁻¹ ·⁷⁵, indicating a low probability of adverse comments and demonstrating the suitability of CLT BB floors for long-span applications.