The Two Alliance Center is a captivating presence on Atlanta’s Buckhead skyline, featuring an entrance that is approximately 140 feet wide, 15 feet deep and 24 feet tall at its apex. The canting glass structure consists of five separate axes. Each glass axis marries to form a multi-axis glass wall, glass roof and glass soffit element. The primary support element of this entry is a ribbed construction made of glass fins and glass rafters. The focal point is a recessed glass soffit area that houses a revolving door and tempered glass swing doors. There is a continuous 20-foot long, 1 1/2-inch thick laminated glass beam that supports the glass system above the revolving door and the tempered glass swing doors.

For this project, Innovative Structural Glass, Three Rivers, Calif., took the architectural intent developed by Smallwood, Reynolds, Stewart, Stewart & Associates Inc. of Atlanta and engineered, designed and supplied the glass entrance system to glazing contractor Trainor Glass, Alsip, Ill., for installation.

“SRSSA’s design was complex in that it was a multi-linear construction of canting and sloping planes of glass that were ultimately interconnected,” says Manuel Marinos, president and CEO, Innovative Structural Glass. “This all-glass structure not only enclosed the ground floor of a multistory office building, but was a self-supporting glass structure capable of resisting wind forces, seismic forces, thermal expansion and contraction, building movements, live load, snow load and water penetration. This design stretched the limitations of both structural glass engineering technology and glass fabrication capability.”

From an engineering perspective, the design required that Innovative Structural Glass design the system using 3D modeling techniques and Finite Element Analysis. This was done to ensure product fit and finish, in addition to structural performance. Custom glass connection brackets had to be specially designed and manufactured to accommodate the design. Innovative Structural Glass had each new design tested by an independent testing agency to verify the engineering results.

Much of the glass was custom oversized pattern cut glass that was tempered, laminated and heat soaked. The complex glass geometry required that state-of-the-art CNC glass machining centers were used to fabricate the glass. Oversized laminating and tempering equipment was also utilized to construct single lites of glass up to 20 feet in length. Due to the complexity of the glass fabrication, its oversized nature and the specifications it had to adhere to, Innovative Structural Glass had the glass fabricated offshore. Most of the glass fabrication was so complex, in order to convey the fabrication requirements for a single lite of glass, Innovative Structural Glass had to create multiple glass fabrication drawings. Before the glass was shipped, the company sent a team of quality assurance inspectors to inspect the glass lites to ensure they met its quality standards. Ultimately, when Innovative Structural Glass shipped the materials to the job site, it supplied a design engineer to provide onsite installation training and assistance.

The Beck Group, headquartered in Dallas, was the general contractor for the project. Crane Revolving Doors, Lake Bluff, Ill., fabricated the entrance’s revolving door.

Source : www.glassmagazine.com