2019 CSCE Annual Conference - Laval (Greater Montreal) Conference
Mr. H. Kurabayashi, Vibro-System
Dr. Dong Ho Ha, Konkuk University
Mr. Andrew Sliasas, Gradient Wind Engineering Inc.
Mr. Vincent Ferraro
Mr. Liam Dupelle, Gradient Wind Engineering Inc.
Mr. Kevin Tarrant, Gradient Wind Engineering Inc.
Tall buildings often require supplemental damping as the only viable solution for serviceability issues such as excessive wind-induced lateral accelerations. Among the various supplemental damping systems available, Tuned Mass Dampers (TMDs) are one of the most compact and easy-to-maintain solutions; for instance, other dampers, such as Tuned Liquid Sloshing Dampers (TLSDs), require a large space with concrete walls and mechanical systems for water supply and drainage, as well as careful maintenance to prevent water leakage. The supposedly compact TMD design often leads to a damper occupying a large space to accommodate pendulum systems or nested-pendulum-type systems. This paper presents Sliding-Type TMDs (S-TMDs) which can provide two(bi)-directional damping through a low-profile design (e.g. the damper rests directly on slab). Typical S-TMDs weighing less than 300 ton can be designed with linear guides, springs and dashpot dampers, whereas TMDs with heavier mass with longer building periods can be better designed with multi-layered rubber bearing-supported TMDs (R-TMDs) in combination with linear guides and springs. The hollow cylindrical rubber bearings of R-TMDs are stacked in groups and layers to the required height that generates TMD frequency. The rubber bearings are organized in groups and layers, and each adjacent layer of each group is sandwiched by a steel plate to achieve overall stability and required flexibility. These R-TMDs are relatively taller than S-TMDs, however the height of 600 to 1,000-ton R-TMDs (for building periods of 10 to 12 seconds) are no more than 5 to 7 meters (m). These heights are substantially shorter than those of pendulum-type TMDs, which require a pendulum height of up to 35 m. This paper also introduces a novel system of an air-floated Mass TMD system, which can reduce the initial static friction of the S-TMD through slightly floating the mass by pressurizing the gap between the mass and the base. Although S-TMDs, when properly installed, can have an initial static friction coefficient as low as 0.3% to 0.4%, this initial static friction coefficient can be even further reduced below 0.1% to 0.2% by ‘floating’ the mass from the rail. This can make the TMD more sensitive even to very low accelerations of 1 to 2 milli-g. This paper presents details of these sliding-type TMDs and their applications to buildings. The proposed new damper systems of S-TMD, R-TMD and air-floated TMD will make building damper design more versatile and economical.