Full scale ambient and forced vibration dynamic measurements
of buildings have become a continuing research activity over the last twenty years or so. One building that has been studied in such a
way was the Imperial County Services Building which was also instrumented with a number of seismographs. On the 15 October 1979, this building suffered major structural damage in a powerful earthquake. This paper briefly describes the ICSB and the damage that occurred, before discussing the computer models that were analysed to study the likely inelastic behaviour of the building. Though the analytical time histories do not show very good agreement with the seismograph results, they do show that the transverse component of the earthquake had a significant effect on the behaviour of the building on account of a non-symmetric arrangement of the ground floor shear walls in the transverse direction. Another factor was the placing of a ground
level slab above the detailed column hinges.