Background
Transportation plays an important role in society from the past to to-date, it helps us to obtain not only in the economic achievement but also in the purpose of daily life. In fact, a bridge is the most essential element regarding transportation since it is built in order to pass over the obstacles. In the procedure of building the bridge, the accurate design and sufficient review process are the two critical methods that need to be involved in order to build the safety project for the long-life usage. There are thousands of bridges around the world that prove their worth since they were constructed under the significant process. The minority, however, is still being considered. The I-35W Bridge which was defined as a truss bridge in Minneapolis, Minnesota was the one of engineering failure since it was fabricated inappropriately. The I-35W Bridge collapsed at approximately 6:05pm on August 1, 2007 resulting in 13 deaths and 145 injuries. The investigation explored that the bridge collapsed because of weak gusset plates fractured under the weight of rush hour traffic. (System Failure Case Studies – A Half-Inch to Failure, 2009) However, the failure could be prevented if the engineers would apply the ethical framework especially in the virtue and utilitarianism regarding their project.
The I-35W Bridge was designed by Sverdrup & Parcel and completed by the industrial construction company Hurcon Inc. in 1967. The I-35W Bridge in Minneapolis, Minnesota over the Mississippi River was approximately 1,900 ft. long and consisted of 14 spans including 5 south approach spans, 3 main spans, and 6 north approach spans. There were four piers used to support the deck truss portion of the bridge that were numbered by five, six, seven, and eight from the south to the north. (Salem et al., 2013) The roller bearings involved at piers five, six, and eight that can be applied between the truss and pier to allow for the thermal expansion and contraction. On the other hand, there was an absence of roller bearing at pier seven which meant that there was no mechanism allowance between them in this position.
The Engineering Failure
Accordingly, the main truss consisted of four types of members including upper chord members, lower chord members, diagonal members, and vertical members. Regarding the structure of the truss bridge, truss members were connected to each other at nodes using gusset plates typically with one plate on each side of the node. In fact, the gusset plates were made from steel ranging in thickness from ½ to 1 inch and were riveted to the members of the truss. (System Failure Case Studies – A Half-Inch to Failure, 2009) By design, the nodes of the I-35W Bridge were labeled starting at 0 from the south end of the south end of the truss to 14 which was at the center of the bridge. Because of north to south symmetry, a prime sign was used to denote the nodes north of the center of the truss. Upper nodes were given at the prefix U and lower nodes the prefix L.
There was the primary cause that contributed to the engineering failure regarding the weak gusset plates fractured under the weight of heavy traffic hours. After the disaster, the National Transportation Safety Board (NTSB) and Minnesota Department of Transportation (Mn/DOT) took a role to investigate the probable cause of this failure. The primary agency reported that the I-35W Bridge collapsed due to under-designed gusset plates which means the thickness of gusset plates must be greater than its actual. It should be noted that the failure of the bridge was starting at node U10. Accordingly, the original design of the bridge was not redundant which can be explained if the failure occurring in the individual member of the truss bridge would cause collapse of the bridge. Regarding the original design, the location of node U10 was near to the inflection point of the truss bridge, the force in the upper chord shifted from the tension on this side to compression on another side while the diagonal members distributed significant compression and tension to the joint. Therefore, there was the presence of a large net shear force that was generated along the horizontal member of the truss. During the investigation, the gusset plate was considered to be under designed; hence, it properly failed if the great amount of shear force acting on it. According to the final report of Adequacy of the U10 & L11 Gusset Plate Designs for the Minnesota Bridge, Holt and Hartmann suggested that the gusset plate at node U10 needed to be twice as thick to safely transfer the shear force produced by design loads. (Holt and Hartmann, 2008)
• Ethical Analysis: The section should analyze the ethical lapses (i.e. stakeholders’ actions, decisions or interests, principles adopted or flouted, risks ignored and reasons for doing so, etc.) that contributed to the engineering failure. You must apply at least one specific ethical framework to your chosen problem. However, before you apply it to your problem, you must give a general explanation of the framework. A good paper will answer the question: Why does this framework apply to the party at fault? Try to brainstorm similar questions that apply to your own topic, and then answer them using at least one of the ethical frameworks you learned about in class to discuss the engineering failure.
Please apply virtue and utilitarianism ethical framework regarding the ethical analysis.
• Recommendation: Drawing on at least one of the ethical frameworks, this section should first propose general ideas and then proceed to very specific recommendations about how to prevent similar failures from occurring in the future. What should have been done? What needs to be done in the future? Don’t make simple arguments (i.e. there needs to be more or better regulations); instead, specify what regulations should be imposed (and by whom), what the parameters of such regulations should be, and how they might be enforced (and by whom). Describe the advantages and disadvantages of the actions you propose and provide justification, again using at least one of the ethical frameworks.
References
Holt, Reggie and Joseph, Hartmann. Adequacy of the U10 & L11 Gusset Plate Designs for the Minnesota Bridge No. 9340. 11 Jan. 2008, www.hsdl.org/?view&did=482686.
Salem, H.M., and H.M. Helmy. “Numerical Investigation of Collapse of the Minnesota I-35W Bridge.” Engineering Structures, Elsevier, 21 Dec. 2013, www.sciencedirect.com/science/article/pii/S0141029613005762.
System Failure Case Studies – A Half-Inch to Failure. Sept. 2009, sma.nasa.gov/docs/default-source/safety-messages/safetymessage-2009-09-01-minneapolis-bridge-collapse.pdf?sfvrsn=1aa1ef8_4.
