The Vierendeel bridges over the Albert Canal, Belgium - their significance in the story of brittle failures

Between 1933 and 1938, some 50 Vierendeel-type welded road bridges were erected in Belgium to provide crossings over the Albert Canal or the Campine canals. They were the first significant applications of electric arc welding in Belgium and constitute the majority of the large welded bridges built at that time in Belgium. It was the heyday of the Vierendeel bridge, which had been invented in 1895 but which had found only limited applications before 1930, with less than 40 built in Belgium and Congo in 30 years. But this rapid application of welding to structural steelwork encountered many problems that were probably overlooked in the climate of euphoria surrounding bridge-building. In March 1938 the Hasselt Bridge suffered a brittle failure. This is generally regarded as the first brittle failure of a large all-welded structure and received much attention at that time. But in 1940 at least three other bridges of this series were also badly fractured and there are indications that some others also experienced serious cracking problems. This paper places theses accidents in perspective in the long story of brittle failures.