Award of Excellence: Parking Structures Category
Strengthening of Agana Beach Condominium Parking Structure
Submitted by Structural Technologies, Inc.
The Agana Beach Condominium in Guam and its adjacent 100-space parking structure were constructed in 1990. The parking structure is of reinforced concrete construction, and consists of basement undercover parking and a similar area of exposed roof parking. Its close proximity to the Philippine Sea and tropical environment, coupled with significant seismic events and typhoons, made this structure very susceptible to damage, both from corrosion and from other natural forces.
In June 1999, the building owner became concerned about cracks that were evident in the parking structure and contacted a local concrete repair contractor to investigate a program of repairs. Several cracks were full depth and efflorescence was evident. Extensive ponding of rainwater was evident on top of the slab surface. It was also noted that an unsuccessful “rout and seal” repair of the cracks had been previously undertaken.
After a visual inspection, the contractor began a more invasive investigation. Digital rebar locators, concrete coring, and test pits were used. It was noted that no notable corrosion was detected in reinforcing steel, and as such the previous “rout and seal” repair had prevented deterioration of this nature. On one visit to the structure, a heavy vehicle was noted on the slab, leading to the conclusion that this was a probable cause of much of the cracking, and leading to the decision to strengthen the slab rather than restrict its use.
A combination of epoxy crack injection, near-surface mounted CFRP pultruded rod encapsulated into the top concrete cover surface, and application of a CFRP wet lay-up sheet system was chosen to repair and upgrade the parking structure. After full-scale load testing, it was determined that the strengthening and repair program was successful. As evidence of the confidence of the longevity of the repairs, the contractor has issued an extended warranty which includes an annual site inspection.