Portland Building Official addresses seismic upgrades for commercial buildings

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It is well known that Portland is situated in a region with the potential for significant seismic activity. The City of Portland, under authority delegated in the Oregon Structural Specialty Code (OSSC), has provisions that set seismic design requirements for existing buildings that undergo changes of occupancy; additions; alterations; repairs from catastrophic damage, fires or earthquakes; or mandatory or voluntary seismic strengthening.

Under Oregon law, the City's Building Official, Natalie Didion, is empowered to provide the final interpretations of state and local building codes when questions arise in the review of development proposals. She recently issued three BODs that seek to clarify when certain seismic standards apply to commercial buildings undergoing particular types of upgrades:

• BOD 26-01 allows a building to conform to a less strict seismic upgrade standard when the occupancy classifications of the area changed are in Relative Hazard Category 5 or 6 (highest classification) as outlined in PCC Table 24.85-A. This applies to one-story buildings that are not changing to a higher risk category.
• BOD 26-02 allows large buildings to increase the additional occupant load threshold up to 149 occupants or 10%, whichever is greater, with respect to the legal building occupancy as of Oct. 1, 2004, before the seismic upgrade requirements in Portland City Code 24.85.040 apply.
• BOD 26-03 allows for the use of an updated American Society of Civil Engineers (ASCE) 41 standard.

Those who are considering improvements to commercial buildings and have questions about these or other seismic upgrade requirements are encouraged to schedule a free 15-minute appointment with a structural engineering reviewer to discuss their projects before seeking a building permit.