A proposed damage model for R/C bridge elements under cyclic loading.

摘要

A damage model is proposed for reinforced concrete elements. The model yields a damage index at a point in the time history for the load on the element, based on the predicted monotonic response from the point in time to failure. The model takes into account the parameters that describe the hysteretic behavior: stiffness degradation, strength deterioration, and ultimate displacement reduction. The model is cumulative and it combines energy, ductility, and low-cycle accumulation. The model is based on the work needed to fail the element monotonically after it experiences cyclic loading and takes the energy under the monotonic load-deformation envelope for the virgin state of the element as a reference capacity. The model modifies the ultimate displacement that the element can achieve, due to low-cycle accumulated damage at the longitudinal reinforcement using the rule in combination with Miner's hypothesis.; The proposed model is applied to 12 bridge columns tested by others. The proposed model gave a realistic prediction of the damage throughout the loading cycles for the test specimens investigated.; An experimental test for a full-scale coupling beam is conducted in this study in order to observe the damage due to cyclic loading. A theoretical prediction of the monotonic force-displacement response of a diagonally reinforced coupling beam is proposed based on a truss model. The model considers the confined concrete between the diagonal reinforcement in the compression direction in addition to the diagonal reinforcement, while only the diagonal reinforcement is considered in the tension direction. The damage prediction of the proposed model compared very well with the observed damage and showed the ability of the proposed model in describing the damage of elements other than bridge columns.; A series of nonlinear dynamic analyses were performed using records from the 1971 San Fernando, 1989 Loma Prieta, 1978 Miyaki-Oki (Japan), and 1999 TW (Taiwan) earthquakes fitted to Vancouver firm ground spectrum with 2% probability of exceedance in 50 years. This study showed that the proposed model is applicable to real bridge columns under real seismic loading. (Abstract shortened by UMI.)