Quebec Bridge Collapse

Head Engineer Head Engineer: Theodore Cooper Highly respected reputation Wanted a monumental project to end his career Unrivalled for the tender Overconfident

The Quebec Bridge company Lack of funds Never built a bridge with a span larger than 300 feet Wanted “quickest and cheapest” solution

Cooper only visited the site 3 times Cooper appointed, Norman McLure, with no experience, to be his eyes and ears on site.

Pre-Construction No preliminary tests and research studies done Bridge was extended an extra 200 feet without any calculations No recalculations of assumed weights for the bridge after revised specifications Theoretical estimates of weights used

Construction continued without dead load being calculated Phoenix Bridge Company’s inspector of materials projected weight of the steel was 11 million pounds heavier than previously estimated. Cooper concluded that Edwards was wrong by 7 to 10%. This was after much of the bridge was fabricated or in place

During Construction Horizontal compression members started deflecting Unable to line up members for riveting As span increased many weight-bearing lower chords were still unriveted Eventually two of the chords from the south cantilever arm bent

Chief engineer in Phoenixville insisted that these chords were bent when they left the shop and that they were still serviceable Cooper sent word to Phenoix Bridge Company to suspend construction which was ignored

Collapse

Two compression cables failed. Sudden collapse! 75 were killed

2nd Collapse A second collapse occurred in 1916 Similar design but two and a half times heavier than its predecessor During the construction the central span which was pre-fabricated dropped into the river while being lifted into place 11 men died.