Nonstructural performance of seismically isolated structures in the near fault region

Seismic isolation is used worldwide to protect a myriad of structures from traditional use to industrial applications. Its success evolves from the use of rigid body motion reducing the demand on the structure especially in terms of drifts. Nonstructural damage refers to the loss of content of a structure including equipment and machinery that can be deemed necessary for facility operation. In many cases, this content is acceleration sensitive especially for machinery with fundamental frequencies above 2 Hz. Most work to date has focused on either nonstructural damage or isolated buildings with little known about the relationship between them. With this in mind, the study herein explores the performance of nonstructural content in seismically isolated structures in the near-fault region with vertical excitation. Using floor level time histories and response spectra, the presence of high frequency content is observed along with areas of decreased performance for the seismic isolation system. The results reinforce the complex relationship between the performance of nonstructural content, seismically isolated structures, and near-fault excitations.