The innovative Puerto Rico Convention Center—notable especially for the striking curved-roof structure that embodies its Caribbean Sea location—opened to much acclaim in November 2005. This spectacular new asset of the Commonwealth of Puerto Rico anchors the growing waterfront Convention Center District in San Juan and has quickly become an icon and feature attraction of the Puerto Rico tourism industry.

The project is the result of the collaboration of the architects, TVS International, Atlanta; and Jimenez + Rodriguez Barcelo, San Juan, Puerto Rico; with the Atlanta office of structural engineers Walter P Moore and local engineer Jorge L. Robert & Associates.

The building’s design implements a wide range of construction methods, materials, and techniques, and extends the notion of what is possible within our profession through innovation, collaboration, and technology. The structure’s unique components warranted the use of many different construction materials, including structural steel, laminated glass, cold-formed steel, reinforced masonry, precast concrete, and both normal- and lightweight-reinforced concrete. Sustainability was incorporated by using locally available materials whenever possible, as well as recycled materials in concrete and steel. The design integrates these very different materials and methods of construction into a beautiful design. Architects can take inspiration from the dramatic way that the structural engineering supported a vision that began as a drawing on paper.

In making this project a reality, Walter P Moore created the one-of-a-kind roof structure while overcoming a number of design challenges. The structure would stand on a reclaimed landfill site subject to liquefaction, in a highly seismic zone, and in the path of Category 5 hurricanes.

A waterfront jewel
The 580,000-square-foot building is the largest convention facility in the Caribbean and Latin America. It features 153,000 square feet of exhibit hall space nestled below meeting rooms on the second and third levels. Eight columns on a 90-foot-by-90-foot grid support the steel structure above the exhibit floor. A 40,000-square-foot ballroom—also the largest in the Caribbean—is perched at the third floor beneath a soaring, exposed roof structure.

Prominent pre-function space and lobbies provide dramatic backdrops for any event. Arriving conventioneers must first pass through the landscaped outdoor plaza, covered by the soaring arched-high roof, particularly spectacular at night when lit up.

Entering guests encounter a spectacular 130-foot-tall lobby space that is fronted by a full-height curtain wall. Views continue to improve as guests ascend the escalators to the meeting rooms and ballroom. A contiguous outdoor patio beneath the high roof offers panoramic views of San Juan, the cruise ship district, and the nearby beaches and surf that inspired the building form.

The roof floats effortless above
The most notable element of the building is its signature roof, which consists of two thin-shell elements that seem to float effortlessly over the building, despite being comprised of more than 3,800 tons of structural steel. High-capacity driven steel piles were required to support the structure and to buttress the roof. While it appears to consist of complex curves, the roof is actually comprised of two simple forms—the high roof and the intermediate roof.

The high roof is elliptical, curving in two directions as it spans 375 feet and reaches a height of 130 feet above the exterior plaza at its apex. The design team selected a structural roof system comprised entirely of steel pipes for beauty, durability, and structural efficiency. A large pylon launches the west end of the arch from the ground. The arch is anchored at its east end by a pair of tree columns. Two 60-inch-diameter pipes frame the perimeter of the high roof, with 24-inch-diameter pipes creating a 15-foot-square infill grid. After conceptual analysis, Walter P Moore added a system of 10.75-inch-diameter diagonal bracing pipes that prevent roof racking and strengthen the overall roof system against hurricane and earthquake loads.

The intermediate roof is formed by a single vault roof that covers the ballroom at the building’s rear, extends out the building’s front to cover the pre-function areas, and curves down to converge at a single pylon support at the ground level. Over the ballroom, the roof is a thin-shell arch comprised entirely of curved, 24-inch-diameter pipe rib members that span 270 feet. Perpendicular 24-inch-diameter pipes finish the arrangement, creating a beautiful and stable roof structure. The front section of the roof is a continuation or extrusion of the same curved geometry over the ballroom, with two large sections cut out of the barrel shape in order to allow it to converge to a single point. This thin-shell arch is framed similarly to the high roof with 24-inch and 60-inch pipes, and spans a maximum of 435 feet while arching to a height of 120 feet above the ground.

Close collaboration between Walter P Moore and TVS ensured that the roof was affordable and straightforward to construct. The structure features highly repetitive dimensions, member sizes, and connections, thereby minimizing the number of different roof elements and greatly simplifying the already complex job of steel detailing, fabrication, and erection. A 3-D CAD model was produced to optimize roof geometry and to define spatial coordinates for each intersecting roof element to within 1/16 of an inch.

Walter P Moore designed all connections, working with both the architects and the steel fabricator, American Bridge Puerto Rico, Inc., to make them economical and aesthetic. Bolted connections minimized labor costs and erection time, and Tekla Corporation’s X-Steel sped detailing of the steel. Articulated bolt end splices along the length of each pipe further simplified erection. The thoughtfulness and coordination of the design allowed American Bridge to shop-assemble entire roof sections to confirm fit-up. These sections were then disassembled, shipped to the site, preassembled on the ground, and lifted onto erection towers. The pipes were shop-primed and then field-coated with a two-part epoxy coating paint system.

Let the sun shine in
A laminated glass skylight covers both roof shells, providing a brilliant level of sunlight for the pre-function areas. Though the mullions and glass panels are segmented for economy over the expansive scale of the roof, the glass appears to curve to follow the sweeping radiuses of the steel roofs.

Anticipating difficulties in panel installation from potential roof movement, expected roof deflections were provided at key points during each stage of construction to allow the skylight manufacturer and erector to build appropriate adjustments into their systems.

Unconventional convention space
To make the 153,000-square-foot exhibit hall highly flexible, the designers created nine 90-foot-by-90-foot column-free bays, as well as three 90-foot-by-150-foot oversized bays on each flank. The space can be subdivided into three individual exposition spaces with suspended operable partitions. Walter P Moore also designed a 10-foot-by-30-foot grid of 1,500-pound capacity hang points at the underside of the structure above. This provides ultimate flexibility for exhibitors to hang a wide variety of elements.

To accommodate the poor soils on the site without compromising the load capacity of the exhibit floor, the structural engineers designed a 10-inch-thick exhibition slab that spans between a grade-beam grid. The slab supports heavy trucks and forklift loading and conceals a grid of utility floor boxes.

A ballroom that suspends belief—and vibration
The 270-foot-by-150-foot ballroom is located directly above the exhibit hall, making the convention center one of just a handful of U.S. venues with a stacked ballroom configuration. Walter P Moore developed a tuned structural system that controls vibrations under a wide variety of activities, including rhythmic and dynamic dances. A 10.5-inch-thick concrete floor slab atop metal deck and steel beams at 10-foot centers is supported on trusses at 30-foot centers that frame the 90-foot-by-90-foot column grid. This structural system effectively controls ballroom floor vibrations while also supporting an efficient rigging grid for the exhibit space below.

A chandelier so large it is known as "the cloud" suspends from the ballroom roof by a grid of steel hangers and beams. The roof also supports a 96,000-pound capacity rigging grid and a suspended operable partition that allows the ballroom to be divided into two smaller spaces. Walter P Moore worked closely with the architect and operable wall manufacturer during design, construction, and installation of the assembly to solve the challenges of suspending such a tall wall from the complex, long-span roof.

Conclusion
Few buildings combine creative architecture, structural expression, and marketing as well as the Puerto Rico Convention Center. The facility opened on time and on budget to rave reviews from the client, the media, and the public. Additionally, the convention center was an excellent investment for Puerto Rico. It provided construction jobs and permanent jobs, as well as significant tourism revenue to the commonwealth, allowing it to compete with other convention destinations throughout the hemisphere. The project was also a catalyst for the redevelopment of a formerly blighted industrial landfill zone that is becoming an active waterfront district. A new convention center hotel is being constructed, and retail and other amenities will soon follow to convert the area into a lively tourist destination.

Doug Robinson, P.E., principal and managing director; Blair Hanuschak, P.E., principal; and Bart Miller, P.E., senior engineer are based in the Atlanta office of Walter P Moore and can be reached at 404-898-9620. They may also be contacted at drobinson@walterpmoore.com, bhanuschak@walterpmoore.com, and bmiller@walterpmoore.com, respectively.

Photo credits:
Convention Center: Brian Gasse/TVS; Structural frame and detail: Walter P Moore

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Design and construction team
Project name: Puerto Rico Convention Center

Owner: Puerto Rico Convention Center District Authority, San Juan, Puerto Rico

Specialty structural consultant: Walter P Moore, Atlanta

Design architect: TVS International, Atlanta

Production architect and architect of record: Jimenez + Rodriguez Barcelo, AIA Architects and Planners, San Juan, Puerto Rico

Structural engineer of record: Jorge L. Robert, MSCE, PSC Structural Consultants, Hato Rey, Puerto Rico

Construction manager: Hardin/QB Construction, San Juan, Puerto Rico

Steel fabricator and erector: American Bridge Puerto Rico, Inc., San Juan, Puerto Rico