The popular Waikiki Shopping Plaza is a 30,000 sf indoor mall in Honolulu that sports a highly visible trellis system on its room. The trellises are purely aesthetic; they does not support vegetation. They are made of two kinds of FRP, and represent an interesting combination of custom-molded architectural elements and off-the-shelf FRP structural elements.
Designed by MGA Architecture, the trellises main canopy pieces are intended to resemble the outriggers of traditional Hawaiian canoes. “Our design was inspired by the native Hawaiian culture to induce sensory response and an emotional experience while blending in with the urban character of modern-day Waikiki,” explains MGA Architecture president and principal architect Matthew Gilbertson.
FRP was chosen to execute the idea chiefly because of light weight, low maintenance, and climate compatibility. The persistent salt-laden ocean breeze would not be friendly to wood, and would pose a corrosion hazard for steel or aluminum. The prospect of frequent maintenance for those materials made corrosion-resistant FRP a good choice. The likelihood of having to replace some or all of the trellises if they were made of the more vulnerable stuff made the FRP an economical choice over the service-life of the building.
Perhaps the most interesting aspect, though, is the use of both custom and off-the-shelf elements. Each trellis consists of four large outriggers, each 28 feet long with a 6″ x 12″ cross-section. These were made using an open molding process by Plas-Tech Ltd, a Honolulu-based custom composites fabricator, which also engineered the trellis system. The outrigger’s cross-members are 28 EXTREN pultruded rectangular FRP tubes, 6.5 feet long, made by Strongwell. Pultrusion is a continuous casting process where reinforcement fibers are pulled through liquid resin (in this case, thermosetting polyester resin) and into a heated die to produce members with a consistent cross-section. Pultrusion manufacturers generally offer a range of standard cross-sections (or “profiles”) that can be used for a wide variety of applications.
Benjamin Rowe, General Manager of Plas-Tech, notes that the incorporation of ready-made structural elements along with the gracefully curved, custom-shaped outriggers allowed a more economical package. The trellises are coated with a premium urethane to protect them against prolonged ultraviolet exposure.
The combination of custom and ready-made FRP is unusual. It points to a growing sophistication of FRP architectural design, and the steady maturation of composites as construction materials.
via CM Magazine (Composites Manufacturing)