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Strengthening Methodology for Lightly Reinforced Concrete Frames-I.

pdf icon Strengthening Methodology for Lightly Reinforced Concrete Frames-I. (2442 K)
Phan, L. T.; Todd, D. R.; Lew, H. S.

NISTIR 5128; 108 p. February 1993.

Available from:

National Technical Information Service
Order number: PB93-161354


frames; reinforced concretes; analytical; dynamic analysis; experimental; hysteresis models; infilled walls; system identification; multi-variable regression


An analytical method for evaluating the inelastic dynamic structural response of lightly reinforced concrete (RC) frames strengthened by infilled shear walls was developed. This method consists of the development of hysteresis failure models for existing and strengthened RC frames and the incorporation of the models into computer program IDARC for use in analytical study. The hysteresis models were developed by, first using the system identification techniques to characterize the load-deformation histories of fifty-five RC frame tests in terms of the stiffness degradation parameter, the strength degradation parameter, and the pinching parameter. Next, multi-variable regressions were performed to relate as functions of the specimen's material and geometric properties and reinforcement parameters. The empirical expressions resulted from these regressions are the hysteresis failure models. The models were validated by analyzing a one-story, one-bay infilled frame, tested by Aoyama et al., and a three-story, one-bay infilled frame tested by Higashi et al. The results of the analyses showed that (1) hysteresis models developed using one-story, one-bay frames can be incorporated into IDARC for the analysis of frames with more than one-story height, and (2) reasonable predictions of structural behavior, both in terms of ultimate load capacity and in absorbed energy on the per cycle basis, can be achieved using the hysteresis models. Thus, in the present form, the hysteresis models can be used in parameter study to assist in the design of strengthening of RC frame structures.