Reader Response - Draft 1

In the web article “I-5 and the Physics of Bridge Collapses”, Hartsfield (2013) claimed that the concept behind a functional bridge design is what leads to its failure as well. The article examined the various types of bridges and found that the different types of bridges have weaknesses specific to themselves.  One such example stated by the article is that truss bridges, which use geometric shapes as a basis for its strength and stability. As such, it is claimed by the article that deformations on the shape will cause the bridge to fail.  Suspension bridges fail due to its inability to withstand huge external forces. The article observed that “when an external force causes the bridge to vibrate at its resonant frequency, it causes the vibration to grow stronger and stronger”. Another example of such a phenomenon are cantilever bridges. The article alleged that cantilever bridges are designed to be able to withstand the torque that the lever arm takes, yet failures are found to be due to construction oversight and overestimation of the torque it can take. The article concluded that understanding a bridge’s weaknesses is indispensable to uncovering the reason behind an unforeseen failure.  

Based on the points elaborated in the news release, I agree that bridges have their own unique design for stability and strength. However, there are exterior factors like maintenance, extreme events and manufacturing defect which might cause a bridge to fail.

 Firstly, bridge failure could be due to poor maintenance. According to an article “Bridge collapse” Schultz and Gastineau (2016) claims that bridge degrades due to exposing to different environmental condition, aging and to “deicing chemicals”. This will cause the essential structure that was meant to rotate becoming fixed, which results in increasing its internal force that damages the bridge. In addition, material that corrodes can cause “section loss” in steel members and concrete reinforcement. This results in weakening the bridge important structure and increase the likelihood of bridge failure. In my opinion, even having a good design for bridge stability and strength is not enough if there are no consistent maintenance checks on the bridge’s material. This is one of the most common exterior factors on why bridge fails.

 Secondly, extreme events could also cause bridge to fail. According to a journal “Multihazard Earthquake and Tsunami Effects on Soil-Foundation-Bridge Systems”, Carey, Mason, Barbosa, and Scott (2019) states that despite having numerous simulation models effects of earthquake and tsunami hazards, there are still limitations when it comes to predicting damage it has on bridges. This shows that although there are many events simulation trying to estimate the damage extreme events have on bridges, there are still no accurate answers for it. Flooding can also cause just as much damage due to debris including trees and buildings that are lifted by the water and pushed forcefully against structural elements of the bridge. This shows that damage done by extreme events is not only immeasurable, it can also do major damage by damaging the essential structural parts which cause the bridge to fail.

Lastly, bridge collapse could be also due to manufacturing defects. According to the article “10 Reasons Why Bridges Collapse”, Ed Grabianowski (2011) states that by looking back into inspection reports and witness accounts of the collapse, sometimes low-grade or faulty materials were used which make the bridge too weak to withstands “rigors of time”. For instance, the collapse of Silver Bridge in Ohio River in 1967. The collapse was due to manufacturing defects in one of the steel eyebars which held the bridge. This shows that even having flawless design, manufacturing defects can also cause a bridge to fail.
In conclusion, although I agree to a certain extent that bridge failure might due to its own design of stability and strength, it will also collapse due to external factors that do not affect its design.

Citation:

Grabianowski, E. (2011, September 13). "10 Reasons Why Bridges Collapse" Retrieved from HowStuffWorks.com. https://science.howstuffworks.com/engineering/structural/10-reasons-why-bridges-collapse.htm

Schultz, A. E. & Gastineau, A. J. (2016) “Bridge Collapsed” Retrieved from Sciencedirect.com. https://www.sciencedirect.com/topics/engineering/bridge-failure

Carey, T. J. , Mason, H. B. , Barbosa, A. R. & Scott M. H. Retrieved from ascelibrary.org https://ascelibrary.org/doi/10.1061/%28ASCE%29BE.1943-5592.0001353