With parking for more than 13,800 vehicles on eight levels, the Sea-Tac Airport Parking Structure is critical to smooth daily operations at the Seattle-Tacoma International Airport –- the 13th busiest in the U.S. Constructed in phases between 1969 and 1999, the cast-in-place, waffle and post-tension (PT) slab/beam parking structure needed critical repair to address serious safety and liability risks. Although testing showed very little concrete deterioration, good-quality concrete, and the PT tendons and concrete cover performing as designed, leaking through the Level 8 floor slab had damaged vehicles and closed down several parking spaces on Level 7. Cracks near the mid-span of the post-tensioned slabs extended for 38,000 lineal feet (with vertical displacement of the slab in some locations), raising concern about structural issues. Various measures had been employed to try to stop the leaks, most of which were unsuccessful.
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