Engineering Mechanics Institute (EMI)

Rocking Isolation: An Effective Strategy for Limiting Forces, Permanent Displacements, Damage and Cost

NHERI Lehigh Seminar Series

December 8, 2021 | 4–5:00 pm EST

Presenter: Dr. Nicos Makris, F.ASCE, Addy Family Centennial Professor in Civil Engineering Southern Methodist University

Abstract: The uplifting and rocking of slender, free-standing structures when subjected to ground shaking may limit appreciably the seismic moments and shears that develop at their base. While the unparalleled seismic performance of rocking isolation has been documented with the through-the-centuries survival of several free-standing ancient temples; and careful post-earthquake observations in Japan during the 1940’s suggested that the increasing size of slender free-standing tombstones enhances their seismic stability; it was Housner (1963) who elucidated a size-frequency scale effect and explained that there is a safety margin between uplifting and overturning; and as the size of the column or the frequency of the excitation increases, this safety margin increases appreciably to the extent that tall, free-standing columns enjoy ample seismic stability.