CCFSS Library (1939 - present)

Alternative Title

Steel research for construction


This report describes experimental and analytical studies of the dynamic behavior of the East Building of the University of California's new Medical Center at San Francisco, California. It also describes experimental tests conducted on the East Building's mechanical service tower and on an adjacent elevator tower. Experimental tests on the East Building were conducted in the summers of 1964 and 1965. Vibrations were produced by eccentric-masstype vibration generators. Frequency responses, time responses, and mode shapes were observed. In the summer 1964 tests, the first mode east-west had 2% of critical damping and the first mode north-south had 1.8%; the values of damping for the higher modes lay in the range 0.4% to 0.9% of critical In the summer 1965 tests, the damping capacity measurements were mostly in the range 5 to 10% of critical. The cause of this increase in damping capacity was investigated in the fall 1965 tests. The fall 1965 tests showed that although the East Building was designed as free-standing, it was dynamically coupled to its adjacent buildings The relatively large damping capacity of this coupled system has been attributed to the Coulomb damping provided by non-structural connections between buildings An analytical model of the East Building was formulated to provide behavior corresponding to the summer 1964 test results. A standard openframe- type model was found capable of representing the dynamic behavior of the real structure. The analytical model was subjected to the El Centro earthquake ground acceleration record in a digital computer analysis. With 5% critical damping in the first few modes, no members of the frame yielded, but when the intensity of the earthquake was increased by a factor of 1.3, some members did yield.


Civil, Architectural and Environmental Engineering


American Iron and Steel Institute

Research Center/Lab(s)

Wei-Wen Yu Center for Cold-Formed Steel Structures


American Iron and Steel Institute

Publication Date

01 Apr 1968

Document Version

Final Version


© 1968 American Iron and Steel Institute, All rights reserved.

Document Type

Technical Report

File Type




Technical Report Number

Bulletin No. 9