In Billings, the sandstone cliffs and the Yellowstone River define the landscape, but the real threats often lie beneath. The 1935 Helena earthquake, felt strongly here, reminded everyone that Montana is not seismically quiet. When a hospital or data center goes up on the south side near the Rimrocks, standard fixed-base construction leaves too much to chance. We approach base isolation seismic design as a direct engineering response to the Intermountain Seismic Belt. The goal is straightforward: decouple the structure from ground motion. Our team applies ASCE 7 Chapter 17 criteria from the earliest schematic phase, ensuring the isolation system period stays above 2.5 seconds. On a recent project near the Billings Clinic, integrating lead-rubber bearings required us to first verify subsurface conditions with test pits to confirm bearing capacity before isolator placement.
A well-tuned isolation system reduces spectral acceleration demands on the superstructure by 60 to 80 percent compared to a fixed-base design in Billings.
