• Located in downtown Atlanta, this mixed-use development consists of a 5-level subterranean parking structure with the 55 Allen and the 45 Allen towers constructed on top – a 14-story office tower and a 28-story hotel/residential tower, respectively.
• During design phase of 45 Allen, additional levels were added to the tower. However, since the foundations and subterranean parking structure were already constructed as part of the 55 Allen Plaza project, the load limits were predetermined. To add the additional levels, semi-lightweight concrete was utilized, instead of normal weight concrete, in the top nine floor levels to compensate for the additional load.
• At the first level, a unique cantilevered and 102-foot-long, curved transfer girder was required at the first level to eliminate columns in the loading dock. A 4-foot-wide by 14-foot-tall transfer girder was designed. using high strength self-consolidating concrete and reinforced with a fully grouted post-tensioning system.

Award of Excellence
McGraw Hill Construction