Thornton Tomasetti provided structural design and construction administration services for Metropolitan Tower, a conversion of the historic Britannica Center and adjacent Karpen Building into luxury residences. Built as the Straus Building in 1924, the 30-story Britannica Center features limestone and brick masonry façades, two basements and a distinctive “beehive” ornamental lantern at the apex. The $70 million project accommodates 243 units, including penthouses; two-story townhomes; and seven levels of parking, including two below grade. The conversion of the landmark building required the removal of the third level and basement floors and construction of two new floors to accommodate the townhomes and parking functions.
The eight-story Karpen Building, built in 1885, underwent a partial demolition and full renovation. As structural and architectural drawings were not available for the existing structure, Thornton Tomasetti performed investigations, invasive exploration, and material testing to determine the gravity system, lateral system, material strengths, structural member sizes, and other information required to fully evaluate the building. The structure required a new lateral system on the west side, as the west wall was removed during demolition. A new system ties the two existing structures together to meet wind load resistance criteria.