This 1956 image shows the world record long-term glue-laminated timber arches being assembled for a 3,500-seat jai alai pediment in West Palm Beach, Florida. The arches had a clear span of 242.5 feet, a rise of 74 feet, and a circumferential length of 294 feet.
Each of the 11-inch-thick arches flared from 25 inches at the base to 46 inches at the crown, were 16 feet apart, weighed more than 15 tons, and contained 17,000 board feet. Wood was chosen for economy and ease of erection.
Plywood templates were constructed to the exact size and shape of the arches, and were used to establish attachment forms and later to cut out the members. Given the large size of the temples, a nearby airport was used as a design plant for pattern construction.
The arches were manufactured by Unit Structures, Inc. in Wisconsin and shipped to Florida in four sections to meet railroad clearance requirements. The sheet was made from 2×12-in. southern pine The longest sheet was over 90 feet.
The worker is tapping the pin into the steel hinge welded to the crown. One of Unit Structures’ partners, Max Hanisch, a German architect and engineer, brought the glulam process to the US, which had been invented and patented in 1901 by Otto Karl Freidrich Hetzer, a German carpenter and inventor.
The pediment was destroyed in a fire in 1978.
