SoFi Stadium: Setting A New Standard In Stadium Design And Construction

SoFi Stadium, the breathtaking new home to two NFL franchises, set out from the beginning to become the standard by which all stadiums will be compared. With a development and construction cost reportedly in excess of five billion dollars, this is the most ambitious stadium ever built. SoFi Stadium is the centerpiece of a 298-acre mixed-use development featuring retail, commercial office space, a hotel, residential units, and outdoor park spaces.

The stadium was designed by renowned stadium architecture studio, HKS, with assistance from structural engineering firm, Walter P Moore. Enclos Tensile Structures was contracted in a design-assist role with the project consultants in developing a technically and commercially viable cable net roof structure and ETFE cladding system, as well as overall project budget, schedule, and coordinated logistics plan.

The stadium is built with an arching steel truss compression ring supporting a double grid cable net roof covered with translucent ETFE and surrounded with perforated aluminum panels. The roof, the largest of its kind ever built, is comprised of 302 ETFE panels, including 46 mechanized vents that allow the heat generated by more than 70,000 spectators to dissipate. The massive roof consists of more than 1400 tons of double orthogonal grid steel, and approximately 67,000 tons of ETFE membrane, secondary steel, gutters, cross clamps, cable struts, and retractable vents. The 20,000-ton steel truss compression ring reaches the ground at three points and has additional support from thirty-seven earthquake-resistant columns as high as 100-feet from grade. The 13-acre stadium roof is open on three sides and is a completely separate structure seismically isolated from the stadium bowl.

Another unique feature of the stadium, situated in the flight path of nearby Los Angeles International Airport, is an enormous installation of 28,000 V-Pix LED lights on the roof that will create a 13-acre high-resolution video display when viewed from above.

Constructing the largest cable net roof ever built for a stadium, one that free spans over 1000 feet longitudinally and 800 feet tangentially, requires one of the heaviest cable structures and, subsequently, one of the highest cable pinning forces ever attempted at approximately 2000 kips. In fact, the stadium’s steel and concrete bowl structure could not support the static dead load from the cable grid, let alone the dynamic movement imposed during the cable jacking and erection process. To overcome this challenge, the upper and lower cable nets were divided into a total of 18 individual nets, and significant scaffolding, matting, bridging, and shoring were involved in reducing the imposed cable loads on the stadium bowl structure to acceptable levels.

Enclos began mobilizing at the stadium site in December 2018. The main cable net was completed in September 2019, the ETFE secondary steel and cladding was completed in June 2020, and the commissioning of the retractable vents and the roof-mounted LED was completed in September 2020.