The extent of vibration energy that a passive TMD dissipates as well as its effective frequency range (bandwidth) increase with an increase in the mass ratio of the TMD. In addition, the amount of internal damping built into the make-up of a passive TMD increases with the size of that TMD. The TMDs used in […]
Read MoreThe use of a tuned damper or a dynamic absorber in time-varying systems can only be effective if they are adjustable (semi-active) and continuously returned to the current resonant frequency of the system. Such dampers require a tuning algorithm that can automatically adjust the adjustable parameter of the tuned damper/absorber, e.g., the stiffness of the […]
Read MoreDEICON’s patented, semi-actively controlled, ‘air suspended tuned mass damper’ (TMD) uses one/multiple air spring(s) as both the restoring (resilient) and the energy dissipating (damping) elements. Feedback control is used to adjust the stiffness and damping of the air spring(s). The schematic of a tuned mass damper installed on a structure is shown in Figure 1. […]
Read MoreTo lower the vibration level of a monumental staircase, one 500 lb tuned mass damper (TMD) was designed, fabricated, and appended to the structure. The natural frequency of the staircase was measured and used for tuning the TMD. Figure 1 shows the landing of the staircase with two of the measurement locations highlighted. Monumental aesthetically […]
Read MoreFollowing the evaluation of the dynamic attributes of a monumental staircase (in an upscale financial office building), one 500 lb tuned mass damper (TMD) was designed, fabricated, and shipped to the job site. Two views of the nearly completed staircase are shown in Figure 1. Monumental, aesthetically pleasing staircases are getting incorporated more and more […]
Read MoreHunter’s Point South Park is a breath-taking waterfront park located on the edge of the East River, in Western Queens, NY. The focal point of the park is Hunter’s Point South overlook, a beautiful cantilevered platform that offers unobstructed views of the New York skyline. The Overlook’s rather low fundamental frequency (3.5 Hz) combined with […]
Read MoreGrant Street Pier, the focal point for “The Waterfront” development in Vancouver, WA is an attractive, triangular, post-tensioned concrete deck overhanging the water by 90 feet providing an expansive view of Columbia River. A cable system and 80-foot-tall mast support the deck. Since the pier is intended for visitors walking on it as well as […]
Read MoreExcessive vibration of a long span balcony (mezzanine) in an upscale residence was addressed by using a tuned mass damper tuned to the natural frequency of the first structural mode of the balcony. The TMD was sized to have the nominal active mass of 450 Kg. The depth and height of the TMD were chosen […]
Read MoreThe irregular shape of three large, 1200 square feet, cantilevered balconies in a high-profile performing arts center resulted in areas at the balcony tip and edge susceptible to potentially annoying levels of vibration. To mitigate this effect, the building designers added tuned mass dampers (TMDs) to the underside of each of the three balconies. Following […]
Read MoreExtensive vibration measurements and numerical analysis of the 2nd floor of a pharmaceutical laboratory floor system conducted by the acoustics consultant of the project revealed that the vibration levels at various bays were well above the laboratory vibration criteria. In coordination with the structural design team, contractor, and client, a two-phase retrofit scheme was proposed […]
Read More