Seismic Isolation of the Terminal Core Roof at the Portland International Airport

The Terminal Core Redevelopment project is an approximately 1.6 billion USD project to functionally expand and seismically upgrade the existing main terminal at the Portland International Airport in Portland, Oregon, USA. At the center of the project is the seismic isolation of a new approximately 350,000 square foot (32,500 m²) mass timber roof. A total of 68 double-concave friction pendulum isolators with displacement capacities ranging between 16 and 22.5 in. (406–572 mm) sit on top of each tine of 34, approximately 53-foot (16.2-m) tall concrete-filled steel Y-Columns on which the mass timber roof is supported. Performance-based seismic design for both a Risk-Targeted Maximum Considered Earthquake (approximately equal to the 2500 year return period event) and a deterministic event on the Cascadia Subduction Zone was pursued. Extensive nonlinear response history analyses considered multiple cases of foundation stiffness and seismic isolator coefficients of friction as well as explicit, time-step-by-time-step assessment of isolator-induced P-Delta and V-h moments. Full-scale, dynamic testing of prototype seismic isolators was performed at EUCENTRE. Quasi-static testing of 100% of production isolators was conducted at either EUCENTRE or SISMALAB prior to shipping to the project site.