In the article, “I-5 and the Physics of Bridge Collapse,” Hartsfield (2013) has stated that most bridges including the I-5 bridge failed due to inevitable design flaws, bridges have weakness inherent to their design. The author implied that an optimal bridge design relies on considerable factors of a project such as cost and timeline. The author also states that the possibilities that can cause a bridge to collapse including construction errors or miscalculations for cantilever, and high external force for suspension bridges. According to Hartsfield (2013), “A truss bridge holds as long as the beams themselves don’t break and the joints stay together.” In this regard, a bridge can collapse once a part of the structural beam fails. He further states that the unfortunate tragedy of the I-5 truss bridge might have been due to the impact caused by a truck, as it crashed into one of the beams. Hartsfield also mentions that nevertheless, it is critical to understand the underlying problem to determine the actual cause of the unpredictable collapse in bridges.
Failure of bridges might be caused by external factors such as human factors and construction method, failure of bridge might not be solely caused by the inevitable design flaws of bridges. There are more factors such as the design flaws of bridge, changing climate and extreme weather events and unexpected incidents that can contribute to the collapse of bridges.
Firstly, the design flaws of bridges have their weaknesses. According to Evans (2017), truss bridges are designed to have compression and tension forces acting on each beam. Forces are transferred from one beam to another. If unaccounted forces happened to act on one of the beams, it can pose danger to the integrity of the truss bridge. Hence if one of the beams fails to perform, this failure will affect the whole structure of the truss bridge which eventually could lead to the failure of the bridge. “According to the American Society of Civil Engineers, bridges in the United States earn a mediocre C+ rating for maintenance and safety. The group reports that one out of every nine bridges in the country is considered structurally deficient” (Bridge Masters, 2017). This statics shows that bridges are structurally flawed which further supports the idea that design flaws of bridge can lead to the collapse of bridges.
Secondly, is one of the unpredictable factors which can contribute to the collapse of bridges. According to Masters (2017), in an event of a flood, water picks up debris like trees, branches or buildings and washes them against the bridge. This might result in structural elements of the bridges to be damaged by the flood. The same article also further states that “Most collapses happen on bridges that were built a long time ago when designers couldn’t imagine the kind of storms they’d have to withstand today” (Bridge Masters, 2017). Engineers design bridges according to the present climate as future climate and extreme weather events cannot be foreseen. Therefore, another factor that can lead to the collapse of bridges is changing climate and extreme weather events
Thirdly, unexpected incidents that engineers cannot foresee can lead to failure of the bridges.
Unexpected incident includes vehicles collapse against the structural component of the bridge could trigger and possibly fail the bridge. For example, an oversized truck hit one of the cross beams and caused the entire collapse of the bridge (Ouellette 2016). If engineers can predict the incident, additional structural support can be added to prevent the collapse of the bridge. “When it comes to bridging construction, engineers simply don’t know what they don’t know. Countless bridge incidents happen because of unanticipated structural or design-related issues” (Bridge Masters, 2017). It further supports the idea that unexpected incidents might lead to the collapse of bridges.
In conclusion, bridges play a big part in road networking which allow easy travel across major rivers and also between neighbouring islands. However, the failure of bridges could also cause injuries and loss of life. More studies could be done to better understand the behaviour of bridges, as past failures can also be put into considered so as to prevent similar failures in the future.
Bridge Masters, Inc. (2017, January 6). 9 Common reason for bridge failures. Retrieved Jan 10, 2020, from https://bridgemastersinc.com/9-common-reasons-for-bridge-failures
Evans, D. (2017, April 25). Truss bridge weaknesses. Sciencing.com. Retrieved from https://sciencing.com/truss-bridge-weaknesses-8668006.html
Hartsfield, T. (2013, May 28). I-5 and the physics of bridge collapse. RealClear Science.com. Retrieved from https://www.realclearscience.com/articles/2013/05/29/i-5_and_the_physics_of_bridge_collapses_106544.htm
Ouellette, J. (2016, August 16). New analysis confirms why the Skagit River Bridge collapsed. Gizmodo.com. Retrieved from https://gizmodo.com/new-analysis-confirms-why-the-skagit-river-bridge-colla-1785842162
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