Project: Second & Plankinton Parking Structure
Location: Milwaukee, Wisconsin
Engineer: HNTB

Winner of the 2001 ICRI Award of Excellence for the Repair of Parking Structures
 
Scope:
 Eight Level Restoration Including Two Helix Ramps
 Hydro-demolition Concrete Removal
 Partial Depth Concrete Replacement
 Full Depth Concrete Replacement
 Vertical Ceiling, Column, Beam Concrete Repairs
 Construction of a New Entrance Ramp
 Placement of Supplemental Reinforcing Steel
 Installation of a 1 ½” Microsilica Concrete Overlay
 Application of Corrosion Inhibiter
 Routing & Sealing of Random Cracks
 Caulking of Control & Construction Joints
 Application of Silane Sealer
 Installation of a Traffic Coating System
 Re-striping & Painting
 
Site Conditions:
 Free Standing Open Garage
 The Garage was only Closed for Three Months
 The Majority of the Repairs were Completed While the Garage was in Service
 Work was carried on throughout the Winter Requiring Supplemental Heating
 Numerous Phases

The 35 year-old Second and Plankinton parking garage is an important asset in the Milwaukee's growing entertainment district. The city's decision to restore it has resulted in a renewed parking resource that exceeded expectations.

Structural modification to enhance safety and efficiency involved the repair of all deteriorated joists, walls, stairwells, delamination of the slabs and repairs to the concrete slabs and walls of the double-threaded helix. Construction joints and slabs were repaired and sealed, and minor repairs were made to the structure's beams and columns. Hydrodemolition removed delaminated concrete and prepared the surface for an overlay on the cantilevered helix slabs, the pan joist slab system and on other selected concrete areas.

Preventative measures were developed to reduce deterioration, including varying the corrosion inhibiting and waterproofing strategies used throughout the garage. On the cantilevered helix slabs and the pan joist system, epoxy coated reinforcing bars and a microsilica concrete overlay were applied. The pan joist slab system on level 2 and 3 also received a traffic-bearing membrane coating. On the garage's top two levels, the concrete was patched and a traffic-bearing membrane coating was applied. A detailed annual maintenance program was implemented.

Architectural modifications to the garage were dramatic and complemented surrounding structures. The north façade features a cityscape with a neon band to create visual interest. The helix enclosure and railings were painted to soften the interior and compliment adjacent buildings. A brighter and more prominent lobby and offices will better serve patrons and staff. New signs and graphics were installed to enhance wayfinding. Improvement to the interior environment involved painting and lighting.

The results of the restoration have more than exceeded the city's goals. There is a waiting list to get into the structure, and the quality parking has attracted new businesses, which use the garage for parking.