Considered by some to be one of the world’s most challenging buildings under construction, the Abu Dhabi National Exhibition Company’s (ADNEC) Capital Gate project recently passed the halfway mark. The tower, which leans 18-degrees westward–14 degrees more than the Leaning Tower of Pisa–includes a giant internal atrium suspended on the 17th and 18th floor; the façade comprises 23,000 square meters of steel and glass elements spiraling skywards.The $35 million glass facade is the responsibility of Austria’s Waagner-Biro, which is handling the steel and glass engineering. The tower will feature Cardinal’s LoE2-240 coated glass laminated with 6-mm clear glass, 16-mm airspace with 13.52-mm laminated clear glass indoors. Architects from RMJM, the United Kingdom-based firm that designed Capital Gate, say the chose the glass “for its anti-glare properties and excellent transparency.”

The glass was produced at Cardinal’s Spring Green, Wis., facility and sold to Intraco Corp. in Troy, Mich., the exclusive distributor for Cardinal CG throughout the Middle East. White Aluminum Factory in Abu Dhabi served as the glass fabricator.

The design of the building poses several challenges with regards to planning, production and erection. In keeping with the triangular configuration of the main supporting structure, more than 700 diamond shaped glass panels will be prefabricated on site from triangular tubes and lifted into position fully glazed. No two of the 12,000 triangular panels are alike.

Because of the tower’s unique posture, the 35-story Capital Gate is being constructed on top of a 2-meter deep concrete raft with an extremely dense mesh of reinforced steel. The steel exoskeleton known as the “diagrid” sits above an extensive distribution of 490 piles that have been drilled 30 meters underground to accommodate the gravitational, wind and seismic pressures. The design of the central core, which slants in opposition to the lean of the building, straightening as it grows, has never been attempted before.

The building’s decorative ‘splash’ is designed to mimic a wave. Besides providing an innovative sunshade for the Capital Gate tower itself, the splash provides a new and creative treatment for the roof of the existing grandstand canopy in the adjoining Abu Dhabi National Exhibition Centre grandstand. The splash is a completely independent structure made of structural steel I-beams fixed to the main building structure.