EL Centro
This spectrum data can be accessed by selecting the file “ELCentro_NS_May18_1940.spe” available in the folder “Spectrum Library” through Layout window >Misc> Spectrums > File > Library.
This predefined data is taken from “J’ Bigs, Introduction to Structural Dynamics” and is based on the north-south component of the May 18, 1940 El Centro California earthquake. As stated in this document, the recorded maximum quantities were 0.33g, 13.7 in/sec, and 8.3 in. This is intended to apply to elastic systems having between 5 and 10 % critical damping. For the El Centro input given below, the three straight lines are defined by.
