Award of Excellence: Parking Structures Category
Alexandria House Condominium Garage and Plaza Rehabilitation
Submitted by Smislova, Kehnemui & Associates, PA
Alexandria House Council of Co-Owners
Smislova, Kehnemui & Associates, PA
Eastern Waterproofing & Restoration Company, Inc.
New York, New York
Lang Tendons, Inc.
The Alexandria House Condominium Garage and Plaza rehabilitation was a $4.4 million dollar project spanning over 28 months that involved the performance of major structural and waterproofing repairs to the three-level cast-in-place concrete post-tensioned structure. The combination of almost 30 years of inadequate maintenance, poor design details, and poor construction details resulted in severe cracking and deflection of the elevated decks of the parking and plaza areas of the condominium.
Visible signs of distress lead the condominium to conduct an extensive condition survey in late 2000 that included physically exposing and examining a portion of each segment of post-tensioning cable in the elevated decks. Exploratory work revealed areas where over 50% of the cables along a column strip were failed due to corrosion-related deterioration and structure analysis work indicated there were some design deficiencies in the structure. The survey lead to the installation of some permanent emergency shoring in some areas of the garage and the condominium quickly planned a thorough repair program for the facility.
Highlights of the project included the removal and replacement of approximately 34,000 linear ft of post-tensioning cables, the installation of almost 8000 linear ft of carbon fiber reinforced polymer (CFRP) strips for flexural strengthening and slab crack control. The project also included the removal and re-construction of a 15,500 square ft plaza deck area that was severely deteriorated and needed to be upgraded for fire truck loading.
The post-tensioning cable replacement work was made extremely difficult due poor sheathing conditions and out-of-plane paths for the existing cable system. The plaza level deck partial reconstruction was challenging as it involved tying a newly constructed post-tensioned slab into an existing structure while maintaining occupancy of the adjacent plaza areas and the garage parking below.