New York — One World Trade Center (WTC) was awarded the 2015 Best Tall Building Award for the U.S. from The Council on Tall Buildings and Urban Habitat (CTBUH). WSP, a global engineering and professional services organization, served as structural engineer for the 104-story office tower on behalf of the Port Authority of New York and New Jersey.

The CTBUH Awards are an independent review of new projects, judged by a prestigious panel of experts. These awards recognize projects that have made extraordinary contributions to the advancement of tall buildings and the urban environment and exhibit processes and/or innovations that have added to the profession of design while enhancing the cities and the lives of their inhabitants. The Best Tall Buildings have been named from each of four competing regions in the world, from nominees representing a total of 33 countries.

One World Trade Center is a new landmark for New York City rising from the northwest corner of the 16-acre (six-hectare) World Trade Center site. The building’s podium has a square plan that matches the dimensions of the original World Trade Center towers, while its roof and parapet heights also symbolically reference the heights of the original buildings. The tower’s eight stainless-steel edges also recall the reflective corners of the original twin towers.

The CTBUH judges noted: “One World Trade Center is of undeniable importance to the Americas as well as the World. The building had high design expectations which the jury felt were met and exceeded.”

“As the tallest building in the Western Hemisphere, soaring to a symbolic height of 1,776 feet, One World Trade Center has become an immediate iconic fixture of the Manhattan skyline,” commented David Cooper, P.E, president U.S. Property & Building sector and chief commercial officer for WSP | Parsons Brinckerhoff. “We are honored to have participated in the redevelopment of the entire World Trade Center site and thrilled to see One World Trade Center recognized by the CTBUH as the best Tall Building in the USA for 2015.”

According to Ahmad Rahimian, director of building structures at WSP and principal-in-charge of structural engineering for One World Trade Center, “WSP was charged with driving early decisions regarding structural design criteria, including resiliency, during a period when codes were being rewritten, that impacted the overall trajectory of the development and evolution of the design.

“One World Trade Center is a unique shape, and it presented a challenge for designers. The footprint starts square, but the corners are gradually cut away from the first office level until it squares off again at 145 feet, rotated 45 degrees. The tower’s height and slenderness imposed very high requirements on the structure’s height and stiffness. The strength of the concrete is 14,000 psi (100 MPa), the highest ever poured in New York City.”

A second WSP project, the Baccarat Hotel on 53rd Street in Manhattan, was also a finalist for the 2015 Best Tall Building Award. WSP provided structural engineering services for the 46-story, 345,000 square foot luxury hotel and residence tower to be located opposite the future MoMA Tower. The tower’s east and west elevations – its main structural components – are sheathed in faceted jet-black aluminum panels. The façades neatly frame the tower’s north and south elevations, whose transparent high-performance glass call to mind Baccarat’s long history of decorative arts. This very slender tower has a slenderness ratio of 14:1.