In many cases, stiffening lively buildings or structures is costly and reduces the amount of usable floor space. Alternatively, the process of supplemental damping provides an economical and effective option to control building accelerations and deflections. At Gradient Wind, we have designed, tested, fabricated and overseen the installation of supplemental dampers in numerous buildings across North America.
The TMD is one of the most efficient types of dampers to control excessive building motions. Leveraging solid mass made of steel or concrete, TMDs provide greater damping for a given space, and their maintenance is much easier compared to other dampers, such as Tuned Liquid Sloshing Dampers (TLSD) or Tuned Liquid Column Dampers (TLCD). Compared to pendulum or double-pendulum type TMDs, which have large space requirements, Gradient Wind’s TMDs are designed to fit in much smaller spaces while providing similar or even greater damping effects. This efficiency is accomplished through a compact design that involves moving mass gliding on linear guides or multi-layered rubber bearings. Gradient Wind provides TMD design, fabrication, installation, and maintenance services.
The TLSD is the most widely used and economical apparatus to control building motions. This device is installed near the top of a building and consists of one or more water-filled tanks fitted with internal baffles. The motion of the water in the tank, tuned to the natural frequency of the building, passes through the baffles and dissipates the energy of the moving structure. The Gradient Wind team can provide initial consultation for damping options, and when necessary, detailed design of the TLSD using our dynamic test rig. This rig simulates the damping effect that the TLSD would impose upon the full-scale building.
Modular Dampers
As a variation of the TLSD, Gradient Wind has invented modular dampers that facilitate simple and more flexible damper installation. Unlike the one large tank of a TLSD, modular dampers consist of many modules (50 to 100) of small-sized fibreglass tanks with an approximate dimension of 9’ (L) ×4’ (2)’ (W) ×1’(H). Due to their small size, modular dampers can be flexibly stacked in smaller spaces while providing damping effects similar to a large TLSD. Other benefits of modular dampers are that they are virtually leak-free, with easy installation and replacement. Moreover, modular dampers do not require large concrete tanks and can be used in the rehabilitation of existing buildings. Lastly, since the installation time can be delayed to follow field monitoring, the most economic damper design is possible after knowing the exact design parameters, such as required supplemental damping levels and building frequencies. As the inventor, Gradient Wind designs, fabricates and installs the modular dampers.
To suppress the vibration of slender structures such as bridge decks, slender towers and flexible sculptures, special damping solutions are sometimes necessary. These include smaller versions of the TMDs used for buildings, Impact Chain Dampers (ICD), and Viscoelastic Dampers (VD). While TMDs and ICDs dissipate vibration energy through “tuned” secondary masses, VDs dissipate the energy through the viscous dissipation of fluid or the plastic deformation of the interfacing material itself. A wide variety of dampers can be used to satisfy different design requirements and unique site conditions.
Empty Tank
With Screens and Water
Monitoring Of Building Motion
Occupants of tall buildings and slender towers can experience uncomfortable motions and accelerations. Our team of experienced engineers determines structural accelerations based on wind tunnel testing and analysis of theoretical building properties. These techniques provide us with the initial estimates of motions. Later, we can perform full-scale measurements on the completed structure to validate our predictions. Finally, we use the information gathered through predictive modelling and physical measurements to mitigate uncomfortable accelerations.
Gradient Wind staff have practical experience monitoring the motions of buildings and structures, the knowledge to design cost-effective damping devices, and the judgement to apply solutions to mitigate excessive accelerations where required. We use state-of-the-art technologies to monitor, retrieve and analyze essential structural properties and structure response data.
