Aerial view of the Leon County Courthouse complex.
Epoxy injecting radial slab cracks prior to strengthening.
CFRP sheets installed to strengthen traffic aisle slabs.
Cast-in-place drop panels to increase punching shear and bending moment capacities.
Two-way CFRP sheets to strengthen slabs (prior to topcoat).
The amount and spacing of reinforcing steel found during investigation varied widely.
Surface grooves cut for NSM CFRP rods for negative moment bending upgrade.
NSM CFRP rods epoxy bonded in pre-cut grooves were used to strengthen traffic-bearing surfaces.
New steel reinforcement of cast-in-place beam to strengthen dumpster area.

Leon County Courthouse Parking Garage Strengthening

Project Description 

The Leon County Courthouse Parking Garage is a cast-in-place concrete structure with a capacity of more than 500 vehicles. It consists of five below-grade parking levels and a five-floor office structure above the parking levels. The garage also is home to a 135 ton memorial statue that sits on top of the courthouse's plaza deck which serves as the roof of the parking garage.

Tests revealed that the existing reinforcement was inadequate to carry the load from the monument. Additional inspection showed signs of serious cracking on all floor levels - leading the owner to pursue and implement a comprehensive structural evaluation and strengthening program. The ultimate goal for the County - a cost-effective and comprehensive solution to restore and improve the capacity of the structural elements of the garage while keeping the entire facility operational

Meeting this goal presented to challenges – one technical, the other economic. Technical issues included determining the as-constructed current capacity of the structure (there were no accurate as-builts), understanding the multiple signs of structural distress and selecting and implementing cost effective solutions that could be performed while the structure was operational.

The economic side of their dilemma was that the complexity of the project was too large for an engineer’s standard specification. Without a comprehensive specification, contractors would have increase pricing to allow for the associated risk.

To address these issues, the County decided to request proposals from teams consisting of engineers, contractors and material suppliers. The teams would be required to demonstrate experience in these types of repairs and offer design build solutions. Each team would go through a multi-step process to provide qualifications, design and pricing.

After three and a half months, a multi-step solution was chosen by the County to meet the needs of the project. Each crack was noted individually -- by location, size and the nature of the crack -- for epoxy injection. Full-depth cracks were pressure-injected; while other cracks were injected by the gravity feed method. For the 35 locations with shear deficiency, steel collars and cast-in-place drop panels were installed. Finally, slabs were strengthened using either a carbon reinforced polymer strip system or span reduction using cast-in-place beams.

Because the structure remained operational, work was scheduled in phases and all work was performed at night and on Saturdays. A special "poly-envelope" was erected and filtration equipment was used to create a dust-free environment. Additionally, regular meetings with the owner ensured open communication with the courthouse occupants and a productive working environment.

The outcome of the project allowed the County to place the monument as desired, as well as move forward knowing that the entire structure was operational at full capacity.