DOME.

Abstract

Tacoma, Wash. built the world's largest wood dome to help refurbish its civic pride, taking only 37 months from bond issue to ribbon cutting. The wood dome is a glulam timber system designed by computer. It is made of 414 curved beams 30 in. (762 mm) deep and 700,000 board ft. of treated Douglas Fir decking. Roofing is 1 one-half in. (38 mm) urethane foam insulation topped by a fluid applied elastomeric membrane. No falsework was needed to erect the dome. A single wood pole supported each of the first 36 components, and once this lower ring was filled in, the roof system became totally self supporting. A cast in place, post-tensioned concrete ring beam transmits the dome loads to 36 concrete columns that are 26 in. (660 mm) in diameter.