Effects of Far- and Near-Field Multiple Earthquakes on the RC SDOF Fragility Curves Using Different First Shock Scaling Methods

Typically, to study the effects of consecutive earthquakes, it is necessary to consider definite intensity levels of the first shock. Methods commonly used to define intensity involve scaling the first shock to a specified maximum interstorey drift. In this study the structure’s predefined elastic spectral acceleration caused by the first shock is also considered for scaling. This study aims to investigate the effects of consecutive far-field (FF) and near-field (NF) ground motions on the exceedance probability of different performance levels of a reinforced concrete single degree of freedom system considering the aforementioned first shock scaling methods. Eight groups of simulations are defined with each considering a combination of FF and NF ground motions. By using elastic spectral acceleration as the scaling method, it is found that the exceedance probability of the second shock performance levels, especially in pulse-like records, greatly depends on the order of far/near field ground motions and the level of damage caused by the first shock. It could be inferred that although first shock scaling method to maximum drift ratio is the commonly used method, the effects of record type multiple earthquakes are more revealed using elastic spectral acceleration as the first shock scaling criteria.