Elegance Restored

Constructed more than 20 years ago, the Atrium is an elegant 20-story contemporary condominium complex convenient to Manhattan. Because of today’s busy lifestyle, condominium owners demand amenities close to home. The Atrium offers health and fitness spas, a sauna, indoor/outdoor pools, tennis courts and concierge services.

Surrounding the Atrium is a 153,200-sq.-ft. outdoor concrete plaza area sitting atop a two-level parking garage. The plaza deck is home to tennis courts, a pool, basketball courts, a children’s play area and a running track. Below the deck, the parking garage accommodates approximately 700 vehicles. Although the plaza and garage were designed to complement the sophisticated elegance of the interior living space, over time, these areas have suffered severe deterioration.

Structure in distress

The plaza deck and parking structure surrounding Atrium Palace were built on cast-in-place concrete foundations stemming from solid bedrock. The parking structure was constructed of cast-in-place concrete reinforced by 0.5-in. unbonded monostrand post-tensioning with mild steel reinforcement in the temperature directions. The post-tensioning system created long spans in the garage to meet the parking requirements. Vehicles accessed the garage through two lower-level entrances and by a ramp to a smaller parking area on the plaza level. Overall, the parking garage encompassed a gross area of approximately 200,000 sq. ft.

Composed of a structural deck with a sheet-applied waterproof membrane, the plaza deck sits on top of the underground parking garage. A thin, unreinforced 3-in. topping slab served as the plaza deck’s wearing slab, and expansion joints were located midway between the plaza deck/parking garage. Before restoration, the plaza deck’s amenities included tennis courts, planter pots, a parking area and vast open concrete deck space, as well as a cast-in-place concrete pool supported by the garage beam infrastructure.

In 2003, maintenance staff for the Atrium Palace first noticed something was wrong and called O&S Associates, an engineering firm, because of visible and extensive shear cracking in the column corbels and beams supporting the parking garage. Failed post-tensioning tendons also were visible throughout the parking garage. Spalls, both horizontal and overhead, were identified in various locations in the garage area. Over the garage, the entire plaza deck topping slab was severely cracked and heaved. Water was leaking through the waterproof membrane to the lower garage levels. The pool also was leaking water into the lower level of the garage, and the plaza deck drainage system was clogged and blocked. Expansion joints had failed and created huge gaps in the slab. The amenities also had deteriorated, adding to the overall effect of these damaged areas.

O&S Associates contacted Structural Preservation Systems to assist with the repair. SPS was interviewed by the board of directors of the condo association and selected for the project. Although the project cost was certainly important and carefully monitored, it was not the deciding factor in choosing a contractor, as SPS was not the lowest bidder. Rather, SPS was hired based on their expertise, resources, project management and financial stability.