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Rotational components of surface strong ground motion
Author(s) -
Oliveira Carlos S.,
Bolt Bruce A.
Publication year - 1989
Publication title -
earthquake engineering and structural dynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.218
H-Index - 127
eISSN - 1096-9845
pISSN - 0098-8847
DOI - 10.1002/eqe.4290180406
Subject(s) - rotation (mathematics) , wavelength , ground motion , rotation around a fixed axis , physics , geology , geodesy , geometry , computational physics , seismology , optics , mathematics , classical mechanics
Rotational components of seismic waves have been estimated using the strong motion array in Taiwan, SMART‐1. The inner rings of accelerographs, covering an approximately circular area of 3 km 2 , permit a decomposition of travelling waves with wavelengths in the range 0.5 to 5.0 km and frequencies from 0.1 to 5 Hz. Rotational components of the strain field, obtained from station pairs and averaged over the array using stacking techniques, were computed for five different earthquakes with M s magnitude 5.7 to 7.8, and epicentral distances 6 to 84 km. The results indicate peak rotation values about a vertical axis on the order of 4 × 10 −5 rad at an approximately 2.5 s period. The measured values for pure rotation and rocking are in agreement with the spatial coherency structure observed in these earthquakes. For comparison, significant effects to engineered structures generally appear when curl u > 10 −4 rad. The estimates are important for design of scaled engineered models for soil‐structure interaction experiments.