A frequency value of 1 means that all values are read, frequency 2 means that every other value is read, frequency 3 means that one in three values is read (typically used in case of files where values of acceleration, velocity and displacement are given in sequence). To open accelerograms saved in this multiple-value per line type of format, users must specify also two additional input file parameters the frequency of reading and the initial values skipped. In the case of example of 1 above, the acceleration column would have the value 2 (values in all other columns are ignored by the program), whilst in the case of example 2, the acceleration column should be defined as 1. To open accelerograms saved in this single-value per line type of format, users must specify one additional input file parameter the column in which the acceleration values are to be found. Further, depending on the type of text file format being, other input file parameters must be defined, as described below: Single-value per line input text files In such cases, it is evidently needed for the last line value to point to the last line of acceleration values. This is a typical behaviour for files coming from a number of strong motion databases whereby velocity and/or displacement time-histories follow their acceleration counterparts.

The last line parameter is also needed for those particular cases where the text file contains additional information after the acceleration values.

For these cases, the first line to be read becomes evidently equal to 32. As an example, consider the corrected accelerogram files obtained from the European Strong Motion Database, where a 31 lines header is usually found. Evidently, these lines are not to be read by the program. Commonly, accelerogram text files contain introductory header lines, describing their source, characteristics, etc. The first line value essentially specifies the number of lines to be neglected from the beginning of the file. In order to open the accelerogram, users should select the File>Open… menu command and then define the respective input file parameters first line and last line to be read, the time-step of the time-history and the scaling factor (if users wish to scale up or down the accelerogram being read). The program can read accelerograms saved in any of the two most popular text file formats used by strong-motion databases single- and multiple-values per line. Defining an acceleration time-history When ran, SeismoSignal opens its main Time Series module, where a given accelerogram can be defined and displayed, preferably by reading it from a text file.

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