The LondonHouse Hotel Project included the renovation of the existing London Accident & Guarantee Building, a City of Chicago Landmark, and the construction of a new 22-story steel framed structure. The new addition provided an additional 70,000 square feet (6,503 square meters) for hotel rooms and amenities. Due to the small footprint, demanding program requirements, and the challenges due to its Landmark status, TGRWA encountered and solved several structural challenges while maximizing the use of the existing elements.
The greatest challenge for the project was the design of the lateral system for the new addition. The solution was to meet the architectural and cost constraints by utilizing a hybrid lateral system. Traditional concentric steel braced frames were placed in the North/South Direction, while utilizing the existing building’s lateral system in the East/West direction. A specially designed expansion joint between the new and existing buildings was planned to allow relative movement in one direction, while locking the structures together in the perpendicular direction.
Another unique challenge for the addition was the building program’s requirement of a column-free open space on the 3rd Floor in order to accommodate a new, large ballroom. The building columns above the ballroom were transferred over a 60’-0” span to limit impact on the ballroom space below. Additional features of the renovation included a new 22nd floor rooftop terrace which required the installation of a hanging elevator at the 21st floor of the existing structure, new openings to accommodate new stairs, and reinforcement for over 60 existing beams for the increased loading. Each of these renovations occurred in a building with an archaic steel and clay tile slab structural system.