These butt splices were bolted to allow for movement. The members under the highest compression loads continued to buckle, and tensions grew on the worksite. It would bridge the St. Lawrence River approximately 14 km north of Quebec connecting into the Grand Trunk rail line. Little did they know that on August 29 that they would also experience one of the largest bridge collapses in history. The Quebec Bridge was included in the National Transcontinental Railway project, undertaken by the federal government. All rights reserved. It took three tries and cost 89 lives, but the city of Quebec was determined to compete with provincial rival Montreal for commercial rail traffic in the late 19th century. Login The bridge is immense, not only in length and weight but in width. The disaster led to new research and testing methods and better designer-contractor coordination. Deux siècles de réalisations, A Span for All Seasons: Pierre LaPorte and Quebec Bridges, Canadian Civil Engineering History and Heritage: Quebec Bridge, Historique et patrimoine du génie civil canadien: Quebec Bridge. The Quebec Bridge Company had enough funds to begin erecting the substructure. It took three tries and cost 89 lives, but the city of Quebec was determined to compete with provincial rival Montreal for commercial rail traffic in the late 19th century. At 67 feet wide, it can accommodate two sets of railway tracks, two sets of streetcar tracks and two roadways. American engineer Theodore Cooper was chosen to design it. His method of accounting for railroad loads on bridge structures became widely used (Middleton 2001, p. 37). Back at the construction site, at roughly the same time the supervisors in Phoenixville were ending their meeting, the Quebec Bridge collapsed at 5:30 p.m. The cantilever arms would reach a total distance of 171.5 m. Spanning the St. Lawrence River near Quebec City, the massive Quebec Bridge has a history of triumph and tragedy. All data contained herein is subject to change and is provided without warranties. The piers were the only part of the structure that survived. The bridge collapsed during construction on August 29, 1907, killing 75 workers. This common practice made the fabrication of these members easier. In fact, the bridge still has its name in the National Historic Site of Canada. The project is located in Quebec, Capitale-Nationale, Quebec, Canada. The serious defects were fundamental errors in design. Do you really want to delete this item from your favorites? In its typical form cantilever arms projecting toward the center of the span from main piers are continuous with and counterbalanced by anchor arms extending between the main piers and anchor pier at each end. An independent consultant may not have allowed the higher than normal design stresses. His decisions were not questioned, even when they seemed to be unusual. The Quebec Bridge was to be one of the engineering wonders of the world. The ends of all the chords were shaped to allow for the small deflections that were expected to occur when the chords came under their full dead load. A cantilever bridge was proposed as the most fea sible design to bridge the harsh, icy waters of the St. Lawrence River. (1908) Royal Commission Quebec Bridge Inquiry Rep. Pearson, C., and Delatte, N. (2006). Great care had to be taken while working around these joints until they were riveted. The top 5.8 m of each pier was made of solid granite. The weight of the suspended span and the cantilever arms is counterbalanced by that of the anchor arms and an anchorage embedded in the anchor pier” (175). The cable-stayed bridge ranks first for a span range approximately from 150 to 600 m, which has longer spanning capacity than that of cantilever bridges , truss bridges, arch bridges, and box girder bridges, but shorter than that of suspension bridges. Some of the other errors such as the underestimated dead loads and the failure to recheck the weight could have been dis- covered before the bridge collapsed. “Collapse of the Quebec Bridge, 1907.” J.Perform.Constr.Facil., Roddis, W. M. K. (1993) “Structural failures and engineering ethics.”, Group 062-10: Engineering Mistakes that caused Bridge Failures. The reconstructed bridge was one of the first large-scale uses of a new nickel alloy steel that could support stresses 40 times greater than carbon steel. The new units’ stresses were accepted based solely on Cooper’s reputation. The causes of the failure are best summarized by the Royal Commission Report. He allowed 145 MPa for normal loading and 165 MPa under extreme loading conditions. © 2020, American Society of Civil Engineers, Access my purchased publications and downloads, Make a donation to support ASCE's activities. A combination of design flaws and management errors caused the first bridge to collapse before completion in 1907. The solution was a rail bridge across the St. Lawrence River requiring a single cantilever span 1,800 feet long - the longest ever attempted. The A9L bottom compression chord, the one already bent, gave way under the increasing weight of the bridge. The specifications were accepted without protest by all interested.”, “A grave error was made in assuming the dead load for the calculations at too low a value and not afterwards revising this assumption. Al- though the workers who failed to report to work because of the deformations lacked the technical expertise, they seemed to be the only ones who understood what was really happening to the bridge (Middleton 2001, p. 78). The failure of these chords was due to their defective design.”, “We do not consider that the specifications for the work were satisfactory or sufficient, the unit stresses in particular being higher than any established by past practice. What materials and systems were used in the construction of this structure? It is worth noting and emphasizing the structure collapse did not come as a surprise to some of the engineers on the project. When completed it would be the largest structure of its kind and the longest bridge in the world, outstripping the famous Firth of Forth Bridge in Scotland. The engineers on site argued among themselves as to the cause. The erection foreman resumed worked the next day (the day before the collapse) without McLure’s permission, because he was confident the deflections were not a large concern. Another ethical concern was Cooper’s rejection of an independent engineer to check his work. The 1,800-foot cantilever span supports its weight 150 feet above the water to allow ocean-going vessels to pass below. Completed in 1917 at a cost of more than $22 million, it is the longest cantilever bridge in … This resulted in a loose and inefficient supervision of all parts of the work on the part of the Quebec Bridge and Railway Company.”. As the drop-in span is lifted into position a stirrup fails and the structure falls into the waters killing 11 workers. Structurae Version 7.0 - © 1998-2020 Nicolas Janberg. It remains the longest cantilever railroad span ever built. Form the mechanical point of view, the cable-stayed bridge is a continuous girder bridge supported by elastic supports. Adding to the design problems, Cooper increased the original allowable stresses for the bridge. Several ethical concerns can be pointed out in this case. What were the causes of the structural failure? At this point, they were to be permanently riveted in place. A year later, the bridge was finally complete. The Quebec Bridge was the longest cantilever structure ever to be attempted during its day (Pearson and Delatte 2006, p. 85). The piers were made of huge granite facing stones with concrete backing (Pearson and Delatte 2006, p. 87). Each pier rested on a concrete filled caisson that was 14.9 m wide, 7.6 m high, and 45.7 m long, weighing 16.2 MN (1,600 t) (Middleton 2001, pp. 48–50). Cooper was a famous bridge builder and consultant out of New York City, and he was chosen to be the consulting engineer for the Quebec Bridge. These were questioned by the bridge engineer for the railways and canals as being unusually high. The bridge collapsed the first time on 29th August 1907. There were no legal ramifications for any of the engineers or foreman. n his long career, he had written an award-winning paper pioneering the use of steel for railway bridges, and had prepared general specifications for iron and steel bridges (Petroski 1995). The twisted remains of the 1907 Quebec Bridge collapse. The fall of this massive bridge can be traced back to several technical factors. The bottom chords for the anchor and cantilever arms in the Quebec Bridge were slightly curved, as shown in Figure 3, for aesthetic reasons.
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