NDM-541: THE HEAT LOADS OF A TUNED MASS DAMPER

Modern tall buildings are often susceptible to excessive wind-induced motions. Tuned mass dampers (TMDs) are used to improve occupant comfort by reducing structural accelerations during common winds, and also to reduce building drift during stronger winds. A TMD is an auxiliary mass that is connected near the top of the structure through elements that produce restoring and damping forces. If the TMD is designed to have the appropriate natural frequency and damping ratio, vibrational energy from the structure is transferred to the TMD where it is dissipated through the TMD damping. This additional source of energy dissipation increases the effective damping of the building, reducing its dynamic motion. The energy dissipating elements of the TMD, whether linear or nonlinear, will convert some of the TMD’s kinetic energy into heat. It is critical that the heat generated by the TMD motion is accurately predicted, and the damping device is demonstrated to be capable of ejecting this heat. If the device cannot eject the heat it generates during operation, the device may overheat, altering its damping properties or potentially leading to device failure. This paper studies the rate of heat generation (power) of a TMD with two common forms of damping. Simple techniques are employed to calculate the mean TMD power. Nonlinear simulations are used to evaluate this simple model, and predict the peak TMD power that is expected over a short period of time. For a given structural acceleration reduction, the TMD power is independent of the form of damping.