Design and Verification of Tuned Liquid Column Dampers for High-rise Buildings Using CFD

Abstract

BMT Fluid Mechanics conducted a comprehensive flow study on the effectiveness of a pair of Tuned Liquid Column Dampers (TLCDs) aimed at mitigating wind-induced accelerations in a high-rise building. The study successfully combined Computational Fluid Dynamics (CFD) with physical model tests performed at the 6 degree-of-freedom shake table facility located at the Department of Civil Engineering of the University of Bristol. The original TLCD concept discussed in this work was proposed at the early design stages of a slender 42-storey high-end residential building located in the Middle East. On-site full-scale measurements and High Frequency Force Balance (HFFB) wind tunnel tests performed by BMT Fluid Mechanics showed that the highest occupied floors could experience excessive wind-induced motion. Depending on the inherent damping of the finished structure, this motion had the potential to exceed standard occupant comfort criteria. A new CFD methodology was developed to assess the performance of the TLCD design using the multi-phase Volume-of-Fluid (VOF) solver and dynamic mesh motion libraries available in the CFD software tool HELYX®. The damping effects introduced by the array of internal porous baffles in the TLCD were approximated using a Darcy-Forchheimer porosity model. Comparisons of free-decay damping performance between CFD results and shake table experiments for a 1:20 scale model of a 3 baffles’ TLCD configuration were found to be satisfactory for design purposes. The results for the amplitude of the net forces acting on the TLCD, as well as the frequency response measured using the free-decay logarithmic decrement approach, confirmed that the proposed CFD methodology provides an accurate representation of real operating conditions. The same CFD approach was successfully applied to model the full-scale TLCD device. With the introduction of a pair of identical purposely designed TLCDs, a 30% increase performance of the structural response of the 42-storey building to wind loading excitation was achieved.