Strong winds can generate large loads on tall buildings and slender structures, often triggering dynamic responses. For this reason, wind loading is generally considered to be one of the most important factors when designing tall structures. Due to the complex interaction of turbulent wind flows and the flexibility of structures, wind loading on buildings can only be measured accurately by wind tunnel testing.
At Gradient Wind, we create model replicas of study sites and their surroundings (typically at a scale of 1:400), install them in the wind tunnel, and perform tests for the full 360° azimuth of wind directions. We then combine the raw data with statistical models of the wind climate for the building’s location to predict wind loads and building accelerations. At Gradient Wind, we have experienced engineers and technicians who are capable of accomplishing project goals quickly and efficiently using our in-house testing and fabrication facilities.
Our studies are conducted using either the High-Frequency Force-Balance (HFFB) technique or the High-Frequency Pressure-Integration (HFPI) technique, which provide the loading and deformation information necessary to design safe structures. Gradient Wind staff also have experience with more complex aeroelastic modelling for unique situations.
After wind loading, occupant comfort and functionality of buildings are the most important priorities in tall building design. Adequate serviceability of a building is assured by controlling accelerations at top occupied floors. Accelerations influencing occupant comfort are related to building deflection (inter-storey drifts) and the interaction of building components.
Building motions increase under stronger wind, but decrease when a building becomes stiffer or has more inherent damping. Beyond these factors, good aerodynamic design of tall buildings can avoid the largest resonant vibrations by detuning the building’s natural vibration from vortex shedding around the building corners for prominent wind speeds.
When detuning by structural stiffening or geometric modification is not feasible or economical, the problematic vibrations can be mitigated by introducing supplemental damping such as Tuned Mass Dampers (TMD) or Tuned Liquid Sloshing Dampers (TLSD), among other options. Information relating to building motions and accelerations are also derived from wind tunnel testing using the HFFB and HFPI approaches. Gradient Wind engineers routinely interact with the design team to provide advice for the most economical solutions to building motion and wind-loading problems.
