The Earthquake Engineering Online Archive

Earthquake simulator study of a reinforced concrete frame

Hidalgo, Pedro A.; Clough, Ray W.

UCB/EERC-74/13, Earthquake Engineering Research Center, University of California, Berkeley, 1974-12, 290 pages (550.3/H49/1974)

This study presents the first test of a reinforced concrete structure conducted at the Earthquake Simulator Lab. located at the Univ. of California, Berkeley. A two-story, one-bay structure, representing the behavior of a typical small apartment or office building, was designed to meet the ductile concrete requirements of the 1970 Uniform Building Code and the ACI 318-71 Code. Using the 20 ft square shaking table, it was subjected to a series of simulated earthquake ground motions with intensity large enough to cause significant inelastic deformations and change in the properties of the structure; the maximum base acceleration achieved was 0.46 g. The test structure was then repaired by injecting epoxy into the cracks and tested again with ground motions of equal or larger intensity than before. The structure was finally tested until failure using a static, horizontal load applied at the top floor. Test results concerning the overall structural response are described, with emphasis on the general characteristics of the response, the varying structural properties of the specimen and the peak values of story displacements, as well as story shear and overturning moment attained during the earthquake simulator tests. These results are discussed in connection with the respective ultimate values given by an elasto-plastic static analysis and the static test. Finally, an analytical study to evaluate the inelastic seismic response and its correlation with the measured performance is presented. The problems involved in predicting the initial stiffness properties of the structure are first discussed. Then, a basic computer model, based on a standard frame system in which bilinear hysteretic hinges may develop at the member ends, is used to obtain the inelastic response. However, in order to improve the correlation, it is necessary to supplement this model with the addition of stiffness degradation and deterioration mechanisms defined with respect to the fundamental mode response of the structure. Good correlation is obtained, but this type of approach needs to be verified with structures having other geometrical properties and mechnical behavior before such analyses can be employed in practice.

Available online: http://nisee.berkeley.edu/documents/EERC/EERC-74-13.pdf (22 MB)