Title: Why did the bridge collapse? | MPR News
Headings: Why did the bridge collapse?
Why did the bridge collapse?
Elizabeth Stawicki
Minneapolis, Minn.
Gallery
Your support matters.

Content: "We've got lots of bridges that get inspected all the time because there is some concern about them, and they go along and serve out their useful life before they're replaced, and don't collapse. It's certainly reasonable to handle a bridge that way," said Curley. Others have raised the question of whether the latest bout of 90-degree days could have contributed to the collapse. Henry Petroski, a structural engineering professor at Duke University, says probably not. Petroski says given Minnesota's wide temperature swings, the engineers designing the bridge would have taken that into account. He says expansion joints allow for that movement with the shifts in temperature. It's conceivable that the joints could have stuck or pushed against the bridge. But he says in general, bridges in areas with wide temperature ranges are more likely to have problems in cold weather, not hot. "When it gets very cold bridges can fail, because the metal gets very brittle when it's cold. So if there are exi