OSF HealthCare Structural Rehabilitation

The historic parking structure was originally constructed in 1950. It is 4 levels and 145,000 square feet with one partial below-grade and one level below grade. Between the parking structure and adjacent building is an integrally constructed finished pavilion space. The parking structure is part of a historically registered district connecting to the adjacent 1920 historically registered office building.

The structure had previously undergone several repair programs, the last completed many years ago. As a result, the structure was severely deteriorated and in a state of disrepair. Due to safety concerns, the structure had been closed for many years. However, after completing renovation of the adjacent connected office building, the Owner’s attention turned to the parking structure. The owner engaged Walker to perform a condition assessment of the structure to evaluate the deterioration and provide repair options.

Walker performed a complete condition assessment of the structure that included visual observations and soundings to record findings, estimate repair quantities, and provide repair options. The team used Ground Penetrating Radar (GPR) and test openings to document existing reinforcement in structural members. Soil test pits and soil borings were performed to determine geotechnic properties of the surrounding soils to evaluate repair options. The assessment found the structure to be in poor condition with over 90% of the roof level beams exhibiting severe freeze-thaw deterioration, an estimated 50% of lower-level beams exhibiting areas of corrosion related distress, and over 50% of the total elevated floor slab areas exhibited corrosion related distress.

After performing the condition assessment, Walker provided the owner with several repair solutions and the owner chose to perform a complete restoration of the parking structure and pavilion area. Walker provided the designs for repairs which included gaining approval for the designs from the State Preservation Office and National Parks Services.

Walker provided repair designs which included:

• Full slab replacement
• Beam and girder replacement (~50%)
• Full replacement of helical ramp slabs
• Reinforcing the basement walls to resist lateral earth pressures
• New traffic bearing waterproofing membranes
• New lighting, plumbing, fire protection, and basement ventilation system
• New wayfinding signage

Due to extensive pre-construction testing and planning, the construction phase was efficient with minimal surprises.  The project was successfully completed within a tight schedule set by grant funding constraints. This project restored a historic structure, lessening landfill waste, reducing the use of natural resources, and was environmentally responsible.