The seismic demand hazard and importance of the conditioning intensity measure

SUMMARY The seismic demand hazard, which gives the rate/probability of exceeding a specified level of seismic demand/response in a given exposure period, is a key measure used to quantify the seismic performance of structures. Because of its simplicity in implementation, the intensity measure (IM)‐based approach is the most common method for computation of the seismic demand hazard. One observed detrimental consequence of the IM‐based approach is that the practical computation of the seismic demand hazard appears to be dependent on the IM used in its computation. This manuscript demonstrates theoretically that the seismic demand hazard for a particular structure at a specific location is unique irrespective of the conditioning IM used in its computation. More importantly, it is demonstrated that this theoretical result can be consistently obtained in a practical context via a six‐step process based around the selection of ground motion records using the generalised conditional intensity measure (GCIM) approach.