[Your College & University Name]
[Date Here]
Introduction: The roof of Hartford Civic Center Coliseum, in Connecticut, USA, collapsed in the early morning of January 18, 1978, during a freezing rain storm after a period of snow. Any loss of life or injury was averted, as the building was empty at that time. However, six hours earlier, on the evening of 17th January, the coliseum was filled with around 5000 basketball fans. Thus, a major disaster was averted (Gammell,B., n.d.). Though the snowstorm was strong, heavy snowstorm occurs in Hartford, Connecticut. The failure of the roof after only 3 years raised many questions about design and analysis procedures undertaken during construction (Smith, & Epstein, 1980 p-59).
Design and Construction: The coliseum was designed by Fraioli Blum Yesselman Associates employing state-of-the-art, structural analysis software package. Its roof was designed as space truss. It had space frame of dimension 300 ft by 360 ft. The space frame rested on 4 pylons to allow spectators unrestricted view of the game. The frame was made of 2300 parts in a framework of modules of dimension 21 ft deep, 30 ft wide, and 30 ft long.
The roof consisted of two main layers. They were made of horizontal steel bars. The nodes of the upper and lower layers were connected by 30 ft diagonal bars. Further, a middle layer of horizontal bars braced these layers. The diagonal layers strengthened the top chord against lateral forces and reduced the unbraced length from 30 ft to 15 ft. The diagonal layers played a crucial part in the design. Further, the cross-shaped structure used in construction instead of I-section or tube-section, has smaller moment of gyration (Rihani, 2013, p-1).
Design differed from the standard design in many respects. Instead of joining at the same point as practiced in conventional design, the intersection of top horizontal bars and the diagonal bars at a different point made the roof especially susceptible to buckling. Another design innovation was connecting the roof panels to the posts instead of attaching directly to the top chords. This design achieved a drainage gradient in the panel by using posts of different height. Use of the posts minimized transfer of bending moment from the roof panels to the space frame (Bardy, 2015).
Cause of Failure: Though the roof of the Hartford Civic Center Coliseum collapsed under a heavy snowfall on January night, the load was 66 between73 psf against design figure of 140 psf. Three agencies Smith and Epstein, Lev Zetlin Associates(LZA), and Loomis and Loomis carried out the investigation to ascertain the cause of the failure. Their findings gave different reasons for the failure. From these reports, it can be inferred that the contributing factors included design errors, overreliance on the software model, an underestimation of the weight of the roof, and deviation of the actual built structure from the design parameters. LZA attributed the primary cause of the collapse to design deficiency. As per their report, bracing of top chords were inadequate. The accumulated snow added weight on the structure leading to buckling of the most overstressed members in the top layer, which in turn, caused other members to buckle. The tension forces acting on the lower layer changed to compression forces causing them to buckle also. The actual frame weight was 23 lb/ft^2 against estimated 18 lb/ft^2 causing overstress. Assumptions made for designing differed from actual construction. While the software package estimated forces based on an unbraced length of 15 ft, whereas during construction unbraced length of the top chords were found to be made of 30 ft. Changes in the diagonal to top chord connection were not according to design. This further aggravated the issue and resulted in the generation of bending moment putting additional stress on the members.
The subcontractor made on-site modifications to the attachment method of the panels. They welded the panels to support beams instead of using predefined bolt holes.
During the assembly and erection, supervision and coordination between different contractors were inadequate.
Conclusion: This case serves as a lesson for future designers, engineering students and practicing engineers. It shows technical, procedural, and ethical issues that require to be addressed during the design and construction of a complex structure to be used by thousands of persons (Martin, and Delatte, 2001). A software package is an analytic tool. Its accuracy depends on the information put into it by the operator. It is essential to check and verify all the information given out.
The construction of space frame roof design with similar truss structure has been used all over the world. Stansted Airport in London and Rogers Centre, originally named SkyDome, in Toronto have used similar design successfully (Johnson , 2009).
References
Bardy, S. , 2015, Hartford stadium collapse: why software should never be more than a tool to be used wisely [online] StructuralEngineer, 92 (2015):8, pp.47-58, The Institution of Structural Engineers, London. Available at: < https://www.istructe.org/journal/ volumes/volume-93-(2015)/issue-8/professional-guidance-hartford-stadium-collapse-wh> [Accessed 1 August 2016].
Gammell,B., n.d, Almost a Tragedy: The Collapse of the Hartford Civic Center [online] Connecticut Public Broadcasting Network and Connecticut Historical Society. Available at: <http://connecticuthistory.org/almost-a-tragedy-the-collapse-of-the-hartford-civic-center/> [Accessed 1 August 2016].
Johnson, R.G., 2009, Hartford Civic Center [online] Available at: <https://failures. wikispaces.com/Hartford+Civic+Center+(Johnson)> [Accessed 1 August 2016].
Martin, R., and Delatte, N.J., 2001, Another Look at Hartford Civic Center Coliseum Collapse. [online] Civil and Environmental Engineering Faculty, Cleveland State University. Available at: < doi/abs/10.1061/(ASCE)0887-3828(2001)15:1(31)> [Accessed 1 August 2016].
Smith, E.A., and Epstein, H.I., 1980, Hartford Coliseum Roof Collapse: Structural Collapse Sequence and Lessons Learned. [online] Civil Engineering-ASCE, 50 (1980): 4, pp. 59-62. Available at: <http://cedb.asce.org/CEDBsearch/record.jsp?dockey=0030537> [Accessed 1 August 2016].
Rihani, S.A., 2013, Structural Failures: A Case Study. [pdf] Structural Engineering Licensure Coalition. Available at: http://www.selicensure.org/sites/default/files/ Hartford%20Coliseum%20Failure%20-%20by%20SAR%20final.pdfhttp://cedb.asce.org/ CEDBsearch/record.jsp?dockey=0030537> [Accessed 1 August 2016].
