A Collection of processed near-field earthquake accelerograms with response and drift spectra

A number of particularly important earthquake accelerograms were measured by instruments that were located in the Near-Field region of several recent earthquakes. For a strike-slip or a thrust fault earthquake, this region is taken to be the area within and immediately adjacent to the surface trace or the surface prediction of the fault rupture plane and its extension to the earth's surface. Such accelerograms are termed near-field earthquake accelerograms. They possess the following features that differ from other earthquake accelerograms: distinctive pulse-like time histories, high peak velocities, and high ground displacements. These features of nm-field ground motion have not yet been well documented and are generally not considered in seismic design. It has been shown, however, that they can place very serious demand on structures located in the near-field region of an earthquake [I]. This report presents uniformly processed data for 12 near-field earthquake accelerograms obtained from four recent earthquakes. The results are presented in the following format: time histories of acceleration, velocity, and displacement rotated to east-west, north-south, and maximum velocity directions, horizontal particle trajectories, Response Spectra for the east-west, north-south, and maximum velocity directions, and Drift Demand Spectra for the east-west, north-south, and maximum velocity directions. Tables 1-4 summarize the relevant information for the earthquakes and near-field accelerograms in this report. Plots of time histories, horizontal particle trajectories, Response Spectra and Drift Demand Spectra are presented in the figures following Table 4. All accelerograms were uniformly corrected using the processing scheme developed by Iwan and Chen [2]. This includes appropriate instrument correction according to the instrument type and baseline correction without band-pass filtering. The time history, Response Spectrum and Drift Demand Spectrum for the north-south component of the El Centro (ELC) accelerogram obtained in the 1940 Imperial Valley earthquake are included in Appendix I for purposes of comparison. As shown by their response and Drift Demand Spectra, all 12 earthquake accelerograms featured in this report place much higher demands on the response and interstory drift of structures than does the standard ELC ground motion. This suggests that the widely used ELC accelerogram may be inadequate for some design purposes. All data processing, response and Drift Demand Spectral computations, and plotting were performed using a Matlab-based package [4