World Trade Center Attack, 2001

WorldTrade Center Attack, 2001

WorldTrade Center Attack, 2001

InSeptember 2011, the World Trade Center Towers in New York collapsed,shocking the world. It was sudden and dramatic and their destructionraised engineering questions. Since then, there are speculations thatthe structures were deficient that the steel columns that theequipments for suppressing fire failed, and other myths andconspiracies as well. The three major events that transpired includethe impact of the airplane, which damaged the columns the ensuingfire that led to the steel losing its strength and becomingdistorted and, without significant tipping, the collapse happenedinwards (Clifton,2001).This paper describes how engineers strive to prevent failure based onstatic principles. In addition, the paper discusses the ethicalfailures that led to the structural collapse of the building. Itbegins with a brief description of the design as a benchmark forunderstanding what engineers consider when designing such megastructures. Even though there are ethical implications inconstruction, engineers have a major responsibility to consider theethics when designing and maintaining structures, the considerationsare only to some specific threshold.

Thetowers represented a fresh approach to skyscraper engineering becauseof their very light weight with modular construction methods to speedthe schedule and curtail costs. Each tower was 64 square meters, 411meters above the street level and 21 meters below the grade,producing a 6.8 height to width ratio. A single skyscraper weighedapproximately 500,000 tons, but designed to resist strong winds witha long return period of more than 50 years. The towers were designedthe lightweight perimeter to resist up to 2kPa (5,000 tons lateralload) wind load (Zdenek,and Zhou, 2001).More so, each building had to resist a huge wind scoop of up to 225km/h hurricane.

Beforethe impact, the Twin Towers were at static equilibrium, whereby theweight of the building was at the center, resulting to a net force ofzero. Even so, the building collapsed because of the aircraft impactcausing the severed steel columns to transfer the buildings` weightto the other undamaged columns. The impact had dislodged thefireproofing material protecting the steel from heat generated byfire (NISTNCSTAR – 1, 2005).The construction-grade steel began to lose its strength at thetemperature of 425 degrees centigrade. According to the (NISTNCSTAR – 1 (2005)report, all the protective insulation was destroyed upon thejetliners` impact, while thousands of jet fuel gallons spilled overmultiple floors, producing temperatures between 800-1000 degreescentigrade (NISTNCSTAR – 1).This weakened the exposed steel, making the buildings to sag, thusthe structural global failure.

TheWTC attack brings with it various ethical implications inengineering. The attack caught the attention of not only theengineers and scientists, but also the ethicists and practitionersderived from various fields. They raised concerns and questions inthe light of engineering, science and technology. Ideally, engineershave the obligation show the highest honesty and integrity standardsto ensure their professional credibility and efficacy (McDowell,2014).More so, engineers rather center on saving the lives of the buildingoccupants than saving the building itself from collapsing this isdone by investing in better safety and evacuation systems designs.Both scientists and engineers are also collaboratively workingtowards thinking speculatively when similar tragedies occur. Throughquantitative reasoning, they are able to sort out facts from fiction.

TheWTC attack demonstrates how engineers consider their designs whileanticipating failure. The towers perimeter tube designs wereconsidered to protect the buildings against failure from impact.Meanwhile, the outer columns were designed to hold the buildings firmduring heavy winds, besides protecting the inner core holding thegravity load. Additionally, as any other skyscrapers, the Twin Towerswere designed such that in the event of a fire breakout, it wouldsupport itself for up to three hours or so – and this would be along time enough for evacuating all the building occupants. Even so,besides other engineering considerations, the twin buildings couldnot withstand the intense heat created by the jet fuel fire.

Followingthe WTC catastrophe, numerous engineering adjustments wereinevitable, further explaining how most of the engineering designsare defensive in nature. Foremost, the emergency communicationssystems would be upgraded as a means of speeding up evacuationnotices in addition to safer egress paths. Emergency simulationsystems would also be designed independently of the normal buildinglighting. Ideally, better structural members fire protection areconsidered in present building constructions including smokeinhalation protection, materials for absorbing energy and redundantegress means. Success of most engineering designs is thus pegged ofperceived failure.

Whatdegree of failure do engineers then anticipate? One may question.Ideally, the towers lasted for up to one to two hours because of twomain factors. First, the fuel load was larger than what the engineersanticipated for a normal office fire. Secondly, a floor space of4,000 square meters was filled with fire within seconds, a situationthat could not be imagined when engineering the buildings. From theseexamples, it is apparent that engineers only perceive failure to aparticular extent. Among other things, for the Twin Towers, it wasnormal office fire that could be put out by office sprinklers. Inaddition, engineers perceived a fire that could spread for minutes,or even hours – and not within seconds – in such a wide floorspace area. Strongly, at no point did the engineers anticipate thatthe buildings could be struck by a commercial airliner. If they didso, motion detection systems would have been in place to detect anyoncoming large bodies in motion such as the commercial planes thatwould strike the buildings. Even though they could,the engineers did not anticipate (besides the flying heights ofplanes jetliner impact) the jet fuel effect.

Inconclusion, the WTC attack has compelled engineers to design betterand safer structures. Even so, the tragedy still stirs up emotionsdue to the ethical implications derived from the tragedy, the mythssurrounding it, and more than two thousand innocent lives lost in theintentional attack. Ideally, engineers perceive natural andunintended tragedies, but only to some degree.

References

Ashley,S. (2001). Whenthe Twin Towers Fell,ScientificAmerican Online.Retrieved March 26,

2015from &ltwww.sciam.com/explorations/2001/100901wtc/&gt.

Clifton,G., C. (2001). Collapseof the World Trade Centers.CAD Headlines.Accessed March

26,2015 from &ltwww.tenlinks.com/NEWS/special/wtc/clifton/p1.htm.&gt

McDowell,J. (2014). EthicsSymposium Meets 9/11 Truth. Achitectsand Engineers for 9/11

Truth.Retrieved March 26, 2015 from&lthttp://www1.ae911truth.org/en/affiliate- marketing-program/898-ethics-symposium-meets-911truth.html&gt.

NISTNCSTAR – 1. (2005). FederalBuilding and Fire Safety Investigation of the World Trade

CenterDisaster: Final Report of the National Construction Safety Team onthe Collapses of the World Trade Center Towers (NIST NCSTAR 1).Retrieved April 15, 2015 from http://www.nist.gov/customcf/get_pdf.cfm?pub_id=909017.

Zdenek,P., B., and Zhou, Y. (2001). Why Did the World Trade CenterCollapse?—Simple

Analysis.J.Engineering Mechanics ASCE.