A Safer Earthquake Design Code After NorthRidge

by Oscar G. de Pineres, (M.ASCE), Principal; ODeP Engineers Associate, San Francisco, CA,

Serial Information: Civil Engineering—ASCE, 1995, Vol. 65, Issue 6, Pg. 72-73

Document Type: Feature article

Abstract: Three recent killer California earthquakes have demonstrated serious deficiencies in our current building codes. As they do after all such events, officials in California and other states that follow the California SEAOC-ICBO-UBC seismic code provisions are debating code provision changes while ignoring the true deficiencies of the seismic design model. The minimum codes are based on an inelastic lower-bound solution that ignores the fundamentals of mathematics and physics. On the other hand, engineers normally adapt mathematical upper bound solutions, then add a design factor of safety above 1.0. to accommodate unknown actual loads. Even though we know little of the expected dynamic forces from earthquakes, the code officials adopted an inelastic lower-bound solution to the earthquake problem and moreover adopted a design factor of safety below 1.0. This unusual switch was no doubt based exclusively on low first cost economics. Recommendations are made and reasons given for changing the code seismic provisions so as to comply with Newton's law of force times acceleration in any direction.

Subject Headings: Seismic design | Standards and codes | Earthquakes | Safety | Dynamics |

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