Routine computer processing of strong-motion accelerograms

This report contains short descriptions, flow charts and listings of the computer programs that are currently being used for routine processing of strong-motion accelerograms at the Earthquake Engineering Research Laboratory of the California Institute of Technology. All programs are in Fortran IV. The programs are presented in five groups corresponding to the processing scheme developed at the Earthquake Engineering Research Laboratory for Volume I, II, III, IV, and eventually Volume V reports (Hudson, et al, 1969; Hudson, et al, 1971; Hudson, et al, 1972a; and Hudson, et al, 1972b). The programs belonging to the Volume I operation are used to check the raw digitized data, to perform the elementary corrections for time and fixed base line, and to scale the raw digitized acceleration data to seconds and G/10 (G is the acceleration of gravity = 981 cm/sec'). The programs belonging to Volume II processing perform the instrument and base line corrections and calculate ground velocity and displacement. The programs for Volume III processing calculate the true velocity spectra, the Fourier amplitude spectra and the pseudo velocity spectra, while the programs for Volume IV compute the Fourier amplitude spectra using the Fast Fourier Transform approach. On the completion of the various stages of processing the output data are plotted, tabulated, punched on cards, and stored on magnetic tapes. The programs for Volume V processing at present plot the RES curves on linear and logarithmic scales by reading the Volume V tape containing the corrected accelerogram and the RES amplitudes.