The focal point of the City of Vancouver, Washington’s new development along the Columbia River is a concrete cantilever pier with an iconic and attractive form. The pier’s triangular, post-tensioned concrete deck overhangs the water by 90 feet and provides an expansive view of the river. A cable system and 80-foot-tall mast support the deck. […]
Read MoreThe long span balcony (mezzanine) in an up-scale large custom-built, single-family residence, overlooking the large open area of floor below had an unacceptable vibratory attribute. The balcony is supported by a long, wide flange (W21) steel beam that supports approximately 600 square feet of tributary floor area. As anticipated and evident from the measured data, […]
Read MoreMonumental, aesthetically pleasing staircases are getting incorporated more and more in the architectural design of institutional and commercial buildings. Monumental staircases frequently cause vibration serviceability issues. This is due to their complex shapes, and long spans, slenderness, and lack of columns. Such staircases vibrates when people climb up and/or down the stairs. Moreover, the […]
Read MoreBased on extensive numerical modeling and measurements the acoustics consultant of the project recommended the stiffening of the frames along with tuned damping of 5 bays of the floor system of a Pharmaceutical laboratory. The floor vibration criterion used was VC-A (50 μm/s RMS in one-third octave bands). The VC criteria take the form of […]
Read MoreThe floor system of a large room at the 3rd floor administration building of a large university with the square footage of around 1760 ft^2s consists of 3 bays exhibited excessive walking-induced floor vibration. This composite floor system is made up of 3 ½” regular weight concrete on 1 1/2” metal deck, supported by 9 […]
Read MoreIn recent years companies with medical imaging equipment have been leasing space in medical office buildings on the upper floors. This is problematic as medical imaging equipment can be very sensitive to vibration velocity. CT, CAT and PET scanners typically are sensitive to vibrations larger than 2,000 micro-in/s and MRI machines are affected by vibrations […]
Read MoreDancing, as in other rhythmic activities, subjects the floor to repetitive loadings. The frequency of dancing load depends on the tempo of the music (normally between 1.5-3.5 Hz and even as high as 4 Hz). Depending on the type of dance, the dancers are either always in contact with the floor or the they are […]
Read MorePassive, tuned acoustic absorbers, such as Helmholtz resonators (HR) and quarter-wave tubes, are commonly used solutions for abating the low-frequency tonal noise in air induction systems. Since absorption at multiple frequencies is required, multiple absorbers tuned to different frequencies are commonly used. Typically, the large size and multiple numbers of these devices under the hood […]
Read MoreGearboxes are typically sources of vibration, either because they are in the transmission path from the engine to the structure so they transmit vibration coming from the engine or they transmit their own vibration at the gear mesh frequency and its corresponding side-bands. The latter can be heard as a whining noise coming from the […]
Read MoreWide column spans along with the use of high strength material make modern floor systems flexible and oscillatory. Walking (as well as other human activities) can induce high levels of vibration in such floors. When the traditional floor vibration control solutions, such as adding architectural features, mass, and/or stiffness to the floor are either not […]
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