Adverse effects of snow and ice on the breakaway resistance of base-isolated buildings

By J. Salmon (Ausenco), J. Sherstobitoff (Ausenco), R. Mortazavi (Ausenco), I. Aiken (Seismic Isolation Engineering Inc.), S. Marusich (Forell Elsesser Structural Engineers Inc.), D. Carson (WSP) & D. Arnold (WSP)

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Base isolation is used to improve the seismic performance of buildings by decoupling the movement of the building from the seismic motion of the ground. A base-isolated building will respond essentially as a fixed-base structure until the lateral breakaway resistance of the isolation system is exceeded. In cold-weather climates, the adverse effects of snow build-up around the perimeter of the building and ice adhesion at exposed sliding surfaces may contribute to the breakaway resistance of the isolation system and may need to be considered in design.

These contributors to the breakaway resistance may be especially problematic for base-isolated buildings in regions of low to moderate seismicity that have low target design base shears. A case study of a base-isolated building in a cold-weather, moderate-seismicity region illustrates that snow and ice effects have the potential to increase the breakaway resistance beyond acceptable limits. Snow removal, either manually or through snow-melt systems, mitigates the adverse effects of snow. Reducing contact areas at sliding interfaces, employing surfaces with low ice adhesion strengths, and providing dehumidification were identified as effective mitigation measures to reduce ice adhesion breakaway resistance.

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