Award of Excellence: Parking Structures Category
State of Michigan/Allegan Street Parking Ramp & Plaza Restoration
Submitted by Carl Walker, Inc.
This $21,000,000 project was located at the heart of the State of Michigan Government Capital Complex. The 33-year-old complex consists of an elevated landscaped area and two below-grade parking levels which encompass four State of Michigan office buildings. The parking structure is directly below the building and plaza, and provides structural support for three of the office buildings. The plaza provides 400,000 square feet (37,000 square meters) of pedestrian area and the parking levels provide 800,000 square feet (74,000 square meters) of parking area. The structural system for the supported plaza and parking levels consists of conventionally reinforced concrete two-way flat slabs, 10 in. (250 mm) thick, spanning to reinforced concrete columns. The plaza consists of precast concrete pavers, planters, open lawn areas, and 4 feet (1.2 m) of soil in most areas. Due to over thirty years of exposure to the Michigan climate and deicing salts, the parking slabs exhibited extensive corrosion deterioration. Furthermore, the plaza deck was poorly drained and there was extensive leaking to the parking level below. Besides the structural damage, the leaking was also causing extensive damage to electrical and mechanical items.
The repairs to the parking ramp consisted of complete removal and replacement of the supported slab with new storm lines, fire protection system, and lighting. The new deck slab contained many durability features, including 2 in. (50 mm) of cover over the top reinforcing, silica fume for reduced permeability, a corrosion-inhibiting admixture, and improved slab drainage. The parking slabs were coated and the walls and columns painted. The repair to the plaza consisted of complete removal and replacement of the existing wearing course, plantings, soil, drainage system, and waterproofing system.
These repairs were performed while maintaining 80% of the parking spaces open for users and while maintaining all building operations without disruption and without compromise for safety.