My explanation for the failure of the\u00a0bridge beams in Edmonton is supported by “new” information. (Ref. 1)<\/p>\n
I said in late March that the beams buckled sideways because the cables from the booms of the construction cranes – moving a little in the wind, tugged on the top of the beam pulling it sideways.\u00a0 The bracing was inadequate and could not resist this tugging. (Refs\u00a02 and 3)<\/p>\n
(A wind and gust forecast for the site would be useful data. \u00a0A site specific forecast meteorologist could give this)<\/p>\n
My reasoning was based on what I saw in pictures on the Internet of the bridge failure.\u00a0 It was an example of how an idea can be given for the cause of something based on limited information.\u00a0 How a hypothesis – an explanation, for an engineering\u00a0failure can be based on limited data, a picture in this case, and revised or supported\u00a0with new data.<\/p>\n
This is the process followed in forensic engineering investigation: Hypothesize, investigate, revise.\u00a0 Hypothesize, investigate, revise.\u00a0 Etc.\u00a0 This process was reflected in remarks by another engineer, Yasser\u00a0Korany, P.Eng., Ontario during a CBC interview.\u00a0 (Ref. 4)<\/p>\n
My “new’ data is the manner in which a steel bridge beam supports itself initially and the bridge deck later.\u00a0 The data is not really “new” because bridge beams have always supported themselves in this way.\u00a0\u00a0The significance of this dawned on\u00a0me when I discussed the bridge failure again with a structural engineer in Halifax.<\/p>\n
In supporting itself, the steel beam compresses at the top a tiny bit – squeezes together, and pulls apart at the bottom.\u00a0 In the process, the steel beam gets a tiny bit shorter at the top and a tiny bit longer at the bottom.<\/p>\n
The shortened beam tries to spring back to\u00a0its original length\u00a0– that’s what steel beams do.\u00a0 It\u00a0tries to do\u00a0this the easy way by moving sideways.<\/p>\n
If something is also tugging the top of the beam sideways, for example, the cable from the boom of a construction crane, then\u00a0the beam\u00a0just might do that – move sideways and buckle.\u00a0 The beam trying to spring back to\u00a0its original length and the crane cable tugging on the beam aid and abet one another in causing the beam to do this.<\/p>\n
The buckled beams in the pictures on the Internet do look a little like the curved sections of a water-filled balloon that has been squeezed.<\/p>\n
References<\/strong><\/p>\n My explanation for the failure of the\u00a0bridge beams in Edmonton is supported by “new” information. (Ref. 1) I said in late March that the beams buckled sideways because the cables from the booms of the construction cranes – moving a … Continue reading \n