The Earthquake Engineering Online Archive

Observations and implications of tests on the Cypress Street Viaduct test structure

Bollo, Martin E.; Mahin, Stephen A.; Moehle, Jack P.; Stephen, Roy M.; Qi, Xiaoxuan

UCB/EERC-90/21, Earthquake Engineering Research Center, University of California, Berkeley, 1990-12, 274 pages (545.1/B64/1990)

Following the 1989 Loma Prieta earthquake, a series of experiments was carried out on an undamaged portion of the Cypress Street Viaduct in order to identify the structural causes of the collapse as well as to study ways of retrofitting other similar freeways. This paper reports, analyzes, and interprets the results of these tests. Experiments conducted include low-amplitude forced vibration tests to determine the dynamic characteristics of the structure and high-amplitude static load tests to assess the strength, stiffness, and toughness of the structure. Both sets of tests focused on response in the transverse direction and were conducted on the structure in its original configuration as well as following partial retrofit. Three different forms of partial retrofit were considered. The final tests of the retrofitted structure were carried out clinically to deformation levels resulting in severe damage.

Available online: http://nisee.berkeley.edu/documents/EERC/EERC-90-21.pdf (21 MB)