Analysis of Wood Truss Connection Failure

Abstract

On November 26, 1985, during the early morning hours, the roof structure at a recently completed shopping center in Longmont, Colorado collapsed following several days of snow and freezing rain. Fortunately, the structure was unoccupied. Photographs taken after the collapse are shown in Figures 1 and 2. Representatives from the architect and structural engineer on site immediately after the collapse conducted density measurements and determined the weight of snow to be on the order of 10.5 to 14 psf. The specified design snow load was 40 psf. Our office was contacted and arrived at the site on December 3, 1985. With a large portion of the snow melted we had to rely on the density measurements conducted by the previous investigators. However, with all of the collapsed trusses in the original failed position, we were able to obtain dimensions of the failed members. Our investigation included