Concrete was economical and added green features to The Encore on 7th, an 18-story retail and residential building in downtown Pittsburgh.
Rising 18 stories, The Encore on 7th stands with its lighted crown as a beacon to those entering Pittsburgh's cultural district. The ground floor contains more than 5000 square feet of retail space, topped with 151 residential units. The 208,000-square-foot complex offers spectacular views and easy access to the city's business center, theater district, and sports stadiums across the river.
Although post-tensioned concrete framing is not common in western Pennsylvania, the owner, architect, and concrete contractor agreed on post-tensioned, cast-in-place concrete as the most economical choice. The project team developed high-strength concrete that included up to 30% recycled fly ash. The mixes saved time on the job, allowing post tensioning to occur in 24 hours instead of the normal two to three days.
Contractors used a placing boom—believed to be a first in Pittsburgh—which reduced the completion time of one level from 10 to five days. Using the boom also provided a higher quality product by minimizing disturbance to reinforcements and post-tensioning cables.
Post-tension construction posed challenges, especially placing sleeves and box-outs, which required extreme precision. Each floor had almost 500 sleeves for conduits, water, storm risers, and sanitary and fire protection systems. Instead of traditional hand layout or core drilling, the data point for each utility was plotted and marked using GPS technology. Subcontractors then centered their sleeves over the tacks quickly and accurately. They placed more than 9000 items in the slab, and fewer than 20 had to be modified.
Whenever possible, contractors recommended local and regional materials. A successful waste management plan ensured that 93% of all construction, demolition, and land clearing waste materials were salvaged or recycled. The project is LEED- certified for new construction.