Upon having the construction of a new church near completion, walking induced vibration was perceived on a long span balcony. DEICON conducted on-site measurements and identified the first two natural frequencies of the balcony. In addition, the participating mass and the damping ratio of mode 1 of the balcony was evaluated. Tuned damping was used […]
Read MoreWalking induced vibration of composite floor system of an office building was controlled at 4 bays, using 8 x 1500 lb tuned mass dampers (TMDs). The measured natural frequencies of the floor system were used in tuning the TMDs targeting the first vibration mode of two bays and first two vibration modes of the other […]
Read MoreTo address the vibration of a monumental staircase in an office building, the structural engineer of the project incorporated a 500 lb tuned mass damper (TMD) into the design. DEICON designed, fabricated the TMD to be installed underneath the landing Figure 1 shows the tuned mass damper. The dynamic attributes of the monumental staircase, namely […]
Read MorePart of an existing building was converted to a medical center with a number of operating rooms. Vibration Measurement of the bare floor system (without any fit-out) pointed to the first natural frequencies of around 6 Hz for various bays. Floor Vibration Limits of Operating Rooms: ISO standard suggests that vibrations in operating rooms not […]
Read MoreFluid/structure interaction and the operation of one of the natural gas compressors imparted dynamic forces onto one of the compressed natural gas piping systems of a power plant. The frequency of this dynamic perturbation happened to nearly match the first resonant frequency of the piping system, which in turn resulted in excessive resonant vibration of […]
Read MorePassive electronic damping using piezoelectric ceramics is a less temperature-sensitive and more tunable alternative to viscoelastic damping treatments. In this damping technique, the mechanical energy of the structure is converted to electrical energy using piezoelectric material. High mechanical stiffness of piezoceramics enables efficient energy transfer to the piezo damper. The electrical energy, in turn, is […]
Read MoreIn four stroke engines, including diesel engines driving generators, each cylinder fires every other revolution. This causes the engine vibration to occur at ½ the engine RPM, called the ½ order vibration, and its higher order harmonics namely 1 order, 1½ order, 2 order. In the case of a diesel generator, in addition to the […]
Read MorePendulum tuned mass dampers (PTMDs) are commonly used in adding damping to tall structures, including high-rise buildings, control and communication towers, stacks, etc. These multi-directional TMDs, which are made up of mass blocks suspended by steel cables or rods, can readily be tuned to the very low natural frequencies associated with the primary modes of […]
Read MoreThe 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 […]
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