PROCEDURES FOR REAL EARTHQUAKE TIME HISTORIES SCALING AND APPLICATION TO FIT IRANIAN DESIGN SPECTRA

With advances in seismic analysis and design of structures, linear and nonlinear time-history analyses are becoming more common in civil engineering area. One of the most important issues for such analyses is the selection of acceleration time histories as input parameter. Generally, international design codes require selection and scaling of acceleration time histories to satisfy the specified design response spectrum at the site of the structure. In literature, there are three sources of acceleration time histories: design response spectrum compatible artificial records, synthetic records obtained from seismological models and accelerograms recorded in real earthquakes. Due to the increase of available strong ground motion database, using and scaling real recorded accelerograms is becoming one of the most contemporary research issues in this field. Generally, two methods for scaling actual time histories to match a given design spectrums are used: scaling in time domain and frequency domain. Selection criteria of proper time history records to fit the design code spectrum account for geological and seismological conditions at specific site. In this study, basic methodologies and criteria for selecting strong ground motion time histories are summarized and the selection and scaling criteria of real time history records to satisfy the Iranian design code are discussed. The time and frequency domain scaling procedures are utilized to scale a number of the available real records to match the Iranian design spectra. The resulting time histories of the two procedures are investigated and compared in terms of suitability as input to time history analyses of civil engineering structures.