Seismic forces in diaphragm design

April 29, 2006
Publication: Proceedings of the 8th U.S. National Conference on Earthquake Engineering, April 18-22, 2006, San Francisco, California, USA v 6 n 1856 p 3545-3554
Author(s): Ronald Mayes Kevin Moore Eatherton, Matthew Naguib, Wassim I Sabelli, Rafael Boardman, Tom

Abstract: The 1994 Northridge Earthquake offered several instances of diaphragms and their components performing inelastically and even causing partial collapse, most notably in parking garages. While diaphragm failures are not widespread, it is clear that inelastic demands can be placed on diaphragms designed in accordance with current code provisions. Actual inelastic demand, however, is not well understood, nor quantified in current design standards and recommendations. An analytical study was conducted on seven buildings to estimate actual diaphragm forces. Accelerations at each floor, as calculated by nonlinear time history analyses, elastic response spectrum analyses and static analyses were compared. It was found that the accelerations determined using nonlinear time histories are as much as five times higher than the accelerations used to design diaphragms according to current code provisions.