by J. Bouwkamp, R. Hamburger and J. Gillengerten
Bouwkamp, J., R. Hamburger and J. Gillengerten (1991). Degradation of Plywood Roof Diaphragms Under Multiple Earthquake Loading . SMIP91
Seminar on Seismological and Engineering Implications of Recent Strong-Motion Data, p. 6-1 - 6-10.
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This paper summarizes the interim findings of research examining the recorded response of three
buildings with concrete walls and plywood roof diaphragms to repeated strong motion events.
Observed stiffness characteristics of the diaphragms are compared for each successive event
and with that predicted by design formula and available data from static tests. Recorded
response of the diaphragms indicates an initial dynamic stiffness substantially in excess of
that predicted by static tests and design formulae. Damping for these diaphragms is determined
to be low, on the order of 5% or less. Degradation of dynamic stiffness, of highly stressed
diaphragms with large aspect ratios is apparent. However, the observed degraded stiffness of
these diaphragms is still in excess of that predicted by conventional design formulae. Research
was performed under a grant from the California Division of Mines and Geology.