Even something as simple as an external fire on a high-rise cannot be defended with the conventional firefighting techniques used throughout history. Unless helicopters or airplanes are deployed, a simple fire on say the 75th floor could wreak havoc. These concerns regarding safety and building size were logged from fire service representatives long before September 11th. As early as 1995, retired Fire Chief of the FDNY, Vincent Dunn wrote that the World Trade Centers were lacking proper evacuation avenues and that if the buildings ever encountered a serious fire, existing procedures would be useless and that people above a certain threshold would not be able to evacuate.

As Taipei 101 prepares to lose the coveted title of the world's largest building, the majority of skyscrapers around the world fall under safety codes implemented for ten story buildings. New safety standards must be created for buildings of 100 or more stories or the occupants will never be completely safe. As the building trends run their course, new safety considerations will be needed. Not only an airplane attack is reason for concern: the basic fire can be just as deadly.

Truss Construction

The term truss means to bind or fasten. In construction terminology, builders support things by using a truss or trusses. The heritage dictionary goes a bit further by pointing out that a truss in a building or construction sense could mean "any of a various number of structural frames constructed on the principles that are other than geometric rigidity of the triangle or deriving stability from other factors, as the rigidity of joints, the abutment of masonry, or the stiffness of beams." An example would be in the case of the World Trade Center towers, as mentioned, the concrete slab floors that were literally anchored to the sides for the buildings by using a truss-construction methodology.

Prior to September 11, engineers would have sworn by the truss construction system as a reliable high-rise technique. No test for truss construction had even conceived of the situation created by the crashing of the two hijacked jetliners turned missiles.

Depending on the type of construction used in newer high-rise buildings, designers take into consideration a number of different types of collapse scenarios. Even though designers were aware of the possibility of fire when they used truss techniques in the Twin Towers, the designers most likely only tested the possibility of construction failure because of normal fire exposure. The September 11 events triggered temperatures well over the norm. Therefore, the type of collapse that occurred on that day was beyond the experience and established history of truss construction methods.

Truss technology has come under fire. However, although the design and construction of the World Trade Center Towers is open to criticism now, the fact that the Twin Towers took over an hour to eventually fall after sustaining direct hits from two fast moving jetliners provides some idea of how strong the buildings actually were. "The fact that the structures were able to sustain this level of damage and remain standing for an extended period of time is remarkable." (Graham-Rowe, 2003)

Firefighters Structural Analysis

The buildings are getting taller. The fact that a 110-story building collapsed in only 8 seconds should put fear in the heart of any fire fighter. Once a firefighter makes a decision to go into a building to help those in need - he must understand ahead of time that 8 seconds most likely will not provide enough time to escape.

From a fire fighters perspective, the Twin Towers departed from accepted high-rise buildings when it came to the construction process. New skyscrapers do not bear the load in the same manner as conventional skyscrapers did in the 19th century. have been built with a skeleton of interior supporting columns that supports the structure. Exterior walls of glass steel or synthetic material do not carry any load.

Conclusion

In conclusion, this report attempted to examine how and why fire fighters continue to show concern regarding the ever increasing size of the world's skyscrapers. When the World Trade Centre towers were completely destroyed on September 11, 2001, many in the fire service were convinced future high rise safety concerns would put an end to the construction of skyscrapers. Yet, the world's demand for newer and taller structures continues to increase. It is apparent that our global population desires high-rise complexes in spite of the catastrophic events of September 11th. Economic indicators such as the currently low interest rates and the high consumer demand will continue to force engineers to reach for new record buildings. Designers, architects and builders seem confident that the only effect in the newer higher buildings will be that any future plane crashes will only generate lots of broken glass and limited structural damage at the point of the impact. Therefore, because of this new found sense of confidence in the design and construction the world demand for high-rises will be higher than ever. But, from a firefighter's perspective, the new found confidence may not be on a solid foundation.

References

Dunn, Vincent (2003). Collapse of Burning Buildings. Retrieved September 24, 2004, at http://www.firenuggets.com/dunn3.htm

Dunn, Vincent. (2002). WHY THE WORLD TRADE CENTER BUILDINGS COLLAPSED:...

Retrieved September 24, 2004, at http://www.firenuggets.com/dunn3.htm
Graham-Rowe, Duncan. (05 February 03). Twin Tower Collapse Theory Challenged. Retrieved September 26, 2004, at http://www.newscientist.com/news/news.jsp?id=ns99993354

Greeman, Adrian (2002). Eastern High-Rise: Record Breaking High Rise Construction Continues Apace In Asia, And Favco Seems To Be The Preferred Crane Of The Job. Cranes Today, July.

Hibbler, R.C. (1999). Structural Analysis (4th Ed.). New York: (Add Publisher).

Infoplease. (n.d.). World's Tallest Buildings. Retrieved September 26, 2004, at http://www.infoplease.com/ipa/A0001338.html

Appendix A Height

Rank Building, city Year Stories m ft

1. Taipei 101, Taipei, Taiwan 2004 101-509 1,670

2. Petronas Tower 1, Malaysia 1998 88-452 1,483

3. Petronas Tower 2, Malaysia 1998 88-452 1,483

4. Sears Tower, Chicago 1974 110-442 1,450

5. Jin Mao Building, Shanghai 1999 88-421 1,381

6. Two International Finance Centre, HK 2003 88-415 1,362

7. CITIC Plaza, Guangzhou, China 1996 80-391 1,283

8. Shun Hing Square, Shenzhen, China 1996 69-384 1,260

9. Empire State Building, New York 1931 102-381 1,250

10. Central Plaza, Hong Kong 1992 78-374 1,227

11. Bank of China, Hong Kong 1989 72-369 1,209

12. Emirates Tower One, Dubai 1999 54-355 1,165

13. Turntex Sky Tower, Kaohsiung, Taiwan 1997 85-348 1,140

14. Aon Centre, Chicago 1973 80-346 1,136

15. The Center, Hong Kong 1998 73-346 1,135

16. John Hancock Center, Chicago 1969 100-344 1,127

17. Ryugyong Hotel, Pyongyang, N. Korea 1995 105-330 1,083

18. Burj al Arab Hotel, Dubai 1999 60-321 1,053

19. Chrysler Building, New York 1930 77-319 1,046

20. Bank of America Plaza, Atlanta 1993 55-312 1,023

21. U.S. Bank Tower, Los Angeles 1990 73-310 1,018

22. Menara Telekom Headquarters, Malaysia 1999 55-310 1,017

23. Emirates Tower Two, Dubai 2000 56-309 1,014

24. AT&T Corporate Center, Chicago 1989 60-307 1,007

25. JP Morgan Chase Tower, Houston 1982 75-305 1,002

26. Baiyoke Tower II, Bangkok 1997 85-304 997

27. Two Prudential Plaza, Chicago 1990 64-303 995

28. Kingdom Centre, Riyadh 2002 41-302 992

29. First Canadian Place, Toronto 1975 72-298 978

30. Wells Fargo Plaza, Houston 1983 71-296 972

31. Landmark Tower, Yokohama, Japan 1993 70-296 971

32. 311 South Wacker Drive, Chicago 1990 65-293 961

33. SEG Plaza, Shenzhen 2000 71-292 957

34. American International Building, NY 1932 67-290 952

35. Cheung Kong Center, Hong Kong 1999 63-290 951

36. Key Tower, Cleveland 1991 57-289 947

37. Plaza 66, Shanghai 2001 66-288 945

38. One Liberty Place, Philadelphia 1987 61-288 945

39. Sunjoy Tomorrow Square, Shanghai 2003 55-285 934

40. Bank of America Center, Seattle 1984 76-284 933

41. Chongqing World Trade Center, Chonqing UC05 60-283 929

42. The Trump Building, New York 1930 71-283 927

43. Bank of America Plaza, Dallas 1985 72-281 921

44. United Overseas Bank Plaza, Singapore 1992 66-280 919

45. Republic Plaza, Singapore 1995 66-280 919

46. Overseas Union Bank Centre, Singapore 1986 63-280 919

47. Citigroup Center, New York 1977 59-279 915

48. Hong Kong New World Building,Shanghai2002 61-278 913

49. Scotia Plaza, Toronto 1989 68-275 902

50. Williams Tower, Houston 1983 64-275 901

51. Wuhan World Trade Tower, Wuhan 1998 60-273 896

52. Renaissance Tower, Dallas 1975 56-270 886

53. Dapeng International Plaza, Guangzhou UC04 56-269 883

54. 21st Century Tower, Dubai 2003 55-269 883

55. Al Faisaliah Center, Riyadh 2000 30-267 876

56. 900 North Michigan Ave., Chicago 1989 66-265 871

57. Bank of America Corporate Center, NC 1992 60-265 871

58. SunTrust Plaza, Atlanta 1992 60-265 871

59. Triumph Palace, Moscow UC04 61-264 866

60. Shenzhen Special Zone Daily Tower 1998 42-264 866

61. Tower Palace Three, Tower G, Seoul 2004 73-264 865

62. Trump World Tower, New York 2001 72-262 861

63. Water Tower Place, Chicago 1976 74-262 859

64. Aon Center, Los Angeles 1974 62-262 858

65. BCE Place-Canada Trust Tower, Toronto 1990 53-261 856

66. Post & Telecommunication Hub,Guangzho2002 66-260 853

Appendix A, cont.

67. Transamerica Pyramid, San Francisco 1972 48-260 853

68. G.E. Building, New York 1933 70-259 850

69. Bank One Plaza, Chicago 1969 60-259 850

70. Commerzbank Zentrale, Frankfurt 1997 56-259 850

71. Two Liberty Place, Philadelphia 1990 58-258 848

72. Philippine Bank of Communications,Makati2000 55-258 848

73. Park Tower, Chicago 2000 67-257 844

74. Messeturm, Frankfurt 1990 64-257 843

75. Sorrento 1, Hong Kong 2003 75-256 841

76. U.S. Steel Tower, Pittsburgh 1970 64-256…