In the glass box: Stadiums exhibit more glazing

The proliferation of stadium construction during the past 10 years indicates the importance of sports in the lives of Americans. However, today’s stadiums serve more than the sporting needs of a city; they have become venues for business and entertainment. Further, the use of glass in stadium construction soars. Glass appears in press boxes, interior railings, super boxes and even exterior façades.

Where stadiums were once isolated due to space and parking requirements, today’s stadiums serve as main attractions in city centers and act as the impetus for revitalization and construction.

San Diego’s $458-million Petco Park, opened in 2004 and designed by HOK Sport+Venue+Event of Kansas City, is an example of a stadium situated  in the city center, near offices, hotels and homes. It features minimally supported laminated glass balustrades at upper levels that serves as barriers to spectators, but do not obstruct their vision onto the field below.

Los Angeles’ Staples Center, whose design includes a glass façade that resembles the prow of a ship, is a sports and entertainment center designed to host more than 230 sports, entertainment and family-oriented events each year. Designed by NBBJ Sports & Entertainment of Los Angeles, the Staples Center has become the focal point of a development plan. Approved by the Los Angeles City Council, the center will result in 4 million square feet of additional building projects, including two hotels, shops, restaurants, live theater, housing and an open air plaza.

The Nationwide Arena in Columbus, Ohio, features a 70-foot glass enclosed atrium and exemplifies the trend for stadiums integrated with urban environments. “Spectators focus inward to the inside action [and] are afforded a view to the outside Columbus skyline,” says Anton Foss, principal at 360 Architecture in Kansas City, Mo. Opened in 2000, the Nationwide houses the Columbus Blue Jackets hockey team. The area around has grown to include offices, a cinema, restaurants and even residential development.

Design trends
Versatility has become a key element of modern stadium design. For example, Houston’s Reliant Stadium, another HOK Sport project, accommodates a minimum of 14 professional football games a year, as well as the annual Houston Livestock Show and Rodeo, concerts, trade shows, conventions and soccer events. Reliant Stadium has a natural grass playing field and two retractable roof panels skinned with translucent fabric panels. These two are increasingly popular design elements finding their way into sports venues. Large areas of glazing mark the sides and ends of the buildings.

A retractable roof tops the new Arizona Cardinals Stadium, designed by architect Peter Eisenman of HOK Sport. As with the Reliant Stadium roof, the “Bird-Air” translucent fabric will allow natural light to pass through the roof while keeping heat and water out, and cool air in.

Designing for energy and the environment
Although development of the Jets New York Sports and Convention Center seems to be dead at the moment, this proposed $1.4 billion 75,000-seat, environmentally friendly stadium on the West Side of Manhattan was intended to incorporate many green features in its design and operation.

The stadium designers aimed to receive Leadership in Energy and Environmental Design Silver certification. “The stadium would have harvested rainwater from the roof for the plumbing system and materials would have been chosen and sourced to meet the requirements of the program,” says Trent Tesch, senior associate principal with Kohn Pedersen Fox Associates in New York City. “In addition, the Jets Stadium would have bought energy from upstate New York wind farms.”

The design of the stadium incorporated a semi-opaque glass curtain around the property. The 600,000 square feet of glazing would have been energy efficient insulating glass. “Our design sees the glass as a delicate glass box, although we do have a security plan for the project,” Tesch says. The first two stories were to have blast-resistant requirements.

All of these monumental projects contain features that glass fabricators and contract glaziers can look to for ideas that might be applied to sports venues in schools and community facilities.

Meeting building-code requirements
Whether the glass is in the exterior façade of the stadium or on the inside to enhance the spectators’ views of the field, it must meet building-code requirements. Chapter 24 of the International Building Code contain the specific requirements for glass.

Requirements for human-impact loads are in Section 2405 of the IBC. Compliance is based on passing test requirements found in the Consumer Product Safety Commission standard 16 CFR, Part 1201. In addition, Section 2406.3 lists all of the hazardous locations requiring safety glazing. These include doors, glazed panels, glazing in guards and railings, and glazing adjacent to stairways, landings and ramps. Following are some examples of requirements for other specific applications that might be found in stadiums and other sports facilities.

Sloped glazing and skylights. Section 2405 of the IBC applies to the installation of glass in skylights, roofs and sloped walls. Laminated glass, an allowable glazing material, would typically be specified because of its ability to retain glass fragments in case it breaks.
Glass in handrails and guards. Section 2407 of the IBC requires glass used as structural balustrade panels in railings to comply with Category II impact requirements of the Consumer Product Safety commission standard CPSC 16 CFR 1201. In addition, a safety factor of four is required.

Loads are specified in Section 1607.7 of the IBC. Handrail assemblies and guards must be designed to resist a load of 50 pounds per linear foot applied in any direction at the top and to transfer this load through the supports to the structure. In addition, they must be able to resist a single concentrated load of 200 pounds applied in any direction at any point along the top, and have attachment devices and supporting structure to transfer this loading to appropriate structural elements of the building.

Engineering hardball
Structural engineer A. William Lingnell of Rockwall, Texas, notes that 3⁄4-inch tempered laminated glass handrails installed in Petco Park, home of the San Diego Padres baseball team, were designed as a cantilever. The glass was laminated by Oldcastle Glass Telford in Telford, Pa., and installed by Sunset Glazing in La Mesa, Calif. The laminated glass utilizes DuPont’s SentryGlas Plus structural interlayer, with 100 times the stiffness of a traditional polyvinyl butyral interlayer and offers better edge stability performance with exposed laminate edges, company officials say.

To verify performance, Lingnell provided the design team with engineering calculations, using the worst case of the two load requirements specified in Section 1607.7 of the IBC. He also tested full-size prototypes in the stadium to show the building officials, architects and the contractor that the glass would not break. In addition, a test rig was brought on site to do safety-glazing impact testing.

As a consultant on many sports stadium projects, Lingnell advises the architects and building owners on the proper type of glass, directions on cushioning, mounting and protecting it once installed. “It is important to understand how materials are combined in the glazing system,” he says. “Care must be taken to verify compatibility, such as with laminated glass and grouting or sealants used in contact with the interlayer.”

The glass must be designed to provide public safety, as well as special design requirements. “Code requirements are a starting point, but glass in stadiums must often be designed to resist loads greater than the minimum code requirements,” Lingnell says.

“An appropriate safety factor must be used to ensure that the public is protected.” Besides calculations, the designer may opt for physical tests to simulate impacts from a flying baseball or hockey puck.

“It is important to understand how materials are combined in the glazing system. Care must be taken to verify compatibility, such as with laminated glass and grouting or sealants used in contact with the interlayer,” Lingnell warns.

Types of glass
“Glass is selected to enhance views from interior spaces to the playing surfaces and other outdoor scenes as well as to provide visibility into the facilities,” says John Williams, associate principal with HOK Sports. “Glass can provide a sense of elegance.”

Williams notes that glass selection relies on experience and advice from experts in glass. Each project requires specific analyses for thermal and shading requirements and to provide the specific appearance desired by the designers. Press and VIP boxes typically utilize laminated glass for safety reasons. If laminated glass breaks, the shards will adhere to the interlayer, minimizing the possibility of injury to spectators. Broken laminated glass will remain in its frame until replacement can be made.

Goal is visibility
The designers of certain sports venues, such as hockey rinks, face the challenge of creating visibility for spectators. Some hockey rinks have installed netting above existing glass panels for safety reasons. New laminated glass products offer an alternative to this approach. “By combining our ultra-clear glass with SentryGlas Plus, we offer a laminated product that increases the spectator’s enjoyment of the game and delivers enhanced safety,” says Pat Kelly, new products manager in the Flat Glass Products Division at PPG Industries in Pittsburgh. “This is especially true when thicker glass is required.”

Although only a handful of architectural firms specialize in stadium design, these firms welcome advice in the specification and selection of appropriate materials for these projects. As more glass is required in stadiums, for interior as well as exterior applications, glass company officials will have an increasingly important role to play in the selection and performance of products.