Beating effect identified from seismic responses of instrumented buildings

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Abstract

Beating effects observed in the recorded responses of buildings are examined in this paper. Beating is a periodic, resonating and prolonged vibrational behavior caused by distinctive close coupling of translational and torsional modes of a lightly damped structure. Repetitively stored potential energy during the coupled translational and torsional deformations turns into repetitive vibrational energy causing the ensuing prolonged motions. Beating, if a dominant response characteristic, may impact the instantaneous and long-term shaking performances of the buildings during earthquakes. In many cases, it is noted that resonance caused by site effects also contributes to accentuating the beating effect. Records from the buildings exhibit structural responses with beating effects. Spectral analyses and system identification techniques are used to quantify dynamic characteristics used in computing beating periods. The beat frequency generally known in acoustical physics is denoted by the absolute value of the differences in frequencies that cause the phenomenon. Engineering implications of the beating may be summarized as (a) prolonged cyclic shaking due to beating effect may take its toll on the structural system, (b) repetitive shaking can accentuate fatigue and low-cycle fatigue, and (c) resonating beating cycles can and do cause discomfort to occupants. Identification of beating effects is the key to find remedial action in modification of dynamic characteristics in order to attenuate or eliminate such effects.

Publication type Conference Paper
Publication Subtype Conference Paper
Title Beating effect identified from seismic responses of instrumented buildings
DOI 10.1061/40946(248)14
Year Published 2007
Language English
Publisher ASCE Library
Contributing office(s) Earthquake Science Center
Larger Work Type Book
Larger Work Subtype Conference publication
Larger Work Title New Horizons and Better Practices
Conference Title Structures Congress 2007
Conference Location Long Beach, California
Conference Date May 16-19, 2007
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