NEHRP Clearinghouse
- Title
- Observations and Implications of Tests on the Cypress Street Viaduct Test Structure.
- File
- PB93114775.pdf
- Author(s)
- Bollo, M. E.; Mahin, S. A.; Moehle, J. P.; Stephen, R. M.; Qi, X.
- Source
- National Science Foundation, Washington, DC.; California State Dept. of Transportation, Sacramento., December 1990, 291 p.
- Identifying Number(s)
- UCB/EERC-90/21
- Abstract
- During the October 17, 1989 Loma Prieta earthquake, a 3/4-mile length of the upper deck of the viaduct collapsed suddenly onto the lower deck. Following the earthquake, a series of experiments was carried out on an undamaged portion of the viaduct in order to identify the structural causes of the collapse as well as to study ways of retrofitting other similar freeways. Results of these tests are reported, analyzed and interpreted in the report. 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 partial retrofits were attempted to mitigate problems with the lower joint region. The final tests of the retrofitted structure were carried out cyclically to deformation levels resulting in severe damage. The test results indicate the importance of considering the strength and deformability of joints when evaluating and retrofitting such highway structures and of identifying the likely hierarchy of member and joint failures. Design implications resulting from these tests are identified.
- Keywords
- Earthquake resistant structures; Elevated highways; Moments; Loma Prieta Earthquake; Test facilities; California; Reinforcement (Structures); Earthquake damage; Dynamic tests; Highway design; Earthquake engineering; Highway improvements; Stiffness; Seismic effects; Rehabilitation; Loads (Forces); Cypress Street Viaduct; Structural analysis