Effect of long-duration earthquakes on the low-cycle fatigue damage in RC frame buildings

Several cases of failure due to rupture of reinforcing bars in RC buildings were reported by inspection teams after the 2010 Muale earthquake in Chile that triggered further research efforts. This paper studies the effect of long-duration earthquakes on the damage potential due to low-cycle fatigue through nonlinear analysis of three existing RC frame buildings. The number of strain cycles and their amplitudes for reinforcing bars at the critical locations within each building were obtained from nonlinear time history analyses. The reduction in the fatigue life has been estimated using S-N curve obtained from the experimental literature and by applying the Palmgren-Miner damage rule. The results showed significant reduction in fatigue life for the low- and medium-rise buildings larger than high-rise buildings. It was found that A706 steel has longer fatigue life than A615 steel. Also, larger diameter steel bars tend to experience less fatigue damage within RC members.