Quasi‐resonance effects observed in the 1994 Northridge earthquake, and others

Article type: Research Article

Authors: Fischer, Edward G. | Fischer, Thomas P.

Affiliations: Fischer Consulting, 5525 Third Street, Verona, PA 15147, USA Tel.: +1 412 793 0224 | Astro Nuclear/Dynamics, Inc., 811 Route 51 South, Large, PA 15025, USA Tel.: +1 412 382 7173; Fax: +1 412 382 4927

Abstract: Sine‐beat phenomena have been found in the 1994 Northridge earthquake records, and they are capable of producing time‐history responses and damaging quasi‐resonance effects in structures. Linear, single DOF (degree of freedom) oscillators, in lieu of nonlinear, multiple DOF systems, have been found adequate to discuss the failures of tall circuit breakers during the 1971 San Fernando and the 1989 Loma Prieta quakes in California. The use of sine‐beat excitation for seismic‐shaking‐table tests of equipment continues to be a conservative simulation of earthquakes.

Keywords: Northridge, earthquake, quasi‐resonance, sine‐beat, circuit breaker

Journal: Shock and Vibration, vol. 5, no. 3, pp. 153-158, 1998