Magic+Mart+Store,+Roof+Collapse,

Magic Mart Roof Collapse //Aaron King // toc
 * Bolivar, TN, July 2, 1983 **

__**Key Words:**__ Magic, Mart, Roof, Collapse, Ponding, Construction, SGH, Tennessee, wide flange, joists, steel, bracing

Introduction
The Magic Mart Building is a single story steel framed retail store located in Bolivar, Tennessee. It collapsed in a severe weather event that brought a large amount of rainfall to the area. This storm was a very strong storm for the area, and as such, didn't last very long, but had a significant impact as shown by this building's failure. The collapse happened during the stores open hours at 6:45 pm on July 2, 1983. Many people were injured, but thankfully nobody was killed in this collapse. Ponding is considered the cause in this collapse along with the addition of roofing materials added throughout the buildings 10 year life without proper removal of older materials. Instability of one of the beam-column connections in the roof framing below the lower section of the rain runoff path caused the collapse, as construction of the building varied from the structural drawings which severely decreased the load carrying capacity of the roof. Most of the survivors of the incident were saved because of the metal racks used to display merchandise. The forensic evidence showed that these racks prevented the roof from completely collapsing to the floor, as they were strong enough to hold up the collapsed debris.

Events Leading Up to the Collapse
The Magic Mart Store was 10 years old when the collapse occurred, not very old in terms of the life of a building. Investigations showed that the roof had been altered with the addition of roofing materials in its service life, and was improperly done so. On the date of the collapse, a large storm swept through the town of Bolivar and the surrounding areas, dropping a large amount of rain onto the area and subsequently, onto the buildings. (Serasota-Herald Tribune, 1983) This accumulation of load, through improper re-roofing and finally from a heavy amount of rain, overloaded the improperly constructed structural system, causing a failure that destroyed most of the building, but through a miracle, did not manage to harm any occupants of the building.



Collapse
At 6:45 pm on July 2, 1983, a single story retail store, Magic Mart, was subject to a high amount of water from a surprise storm that occurred in the area. This retail store is part of a line of shops along the side of the road in Bolivar, Tennessee. The building was designed with steel wide flange girders and the roof consists of typical steel bar joists. The columns in the building that supported the girders were steel pipe columns. Through investigation, it was shown that the building was constructed differently than it was designed. Smaller, weaker members were used and oriented 90 degrees in comparison to the construction drawings, and the bar joists did not have sufficient bottom chord extensions and stiffener plates to create sufficient strength in the roof structure.

To make matters worst, the construction drawings were not stamped by an architect or engineer, but were prepared by an architectural firm. These drawings, like any drawings used, need to be stamped by a registered professional. While the investigators did not find any issues with the structural designs holding the design loads, there was no designer or structural design representative in the field at the time of construction, and this caused the construction to be sequenced in correctly and fabricated incorrectly and with the wrong sizes. These incorrect construction methods led to a structure that could not hold the design loads, and the roof work done added load and caused the ponding to be more severe, which initiated the collapse. The structure then progressively collapsed, a direct cause of the poor construction methods and incorrect structural members used in the building. The two figures below show the difference between the as designed, and as built contruction.





Investigation & Cause of Failure
After the collapse on July 2, 1983 Simpson, Gumpertz & Heger, Inc. arrived on site about a month later, on August 4th, 1983. It was noted that even though a rescue attempt had occurred, the collapse site was still relatively undisturbed. After doing a survey of the collapsed building, SGH attempted to recreate the slope of the building and found that because of the incorrect beam size, the building was not sloped to drain to the rear correctly. There was a low spot towards the back of the building, but it allowed about 3 inches of rain to pond on the roof. It was determined through investigation of the materials that the roof had been patched and re roofed without properly removing the under layers. This only added to the dead load on the roof and the eminent collapse. This low point in the roof was the point where the collapse started. After the rain overloaded the roof, the improperly braced and structurally weak girders and joists progressively collapsed. The welds and connections were sufficiently strong, which helped with pulling the rest of the roof down once the collapse was initiated. (Bell and Parker, 1987)

As mentioned earlier, it was also uncovered during the investigation that neither the architecture firm, nor the structural engineer visited the site at any time throughout the construction. (Construction Failures p. 197-198) Even a single field inspection may have prevented the large construction errors, such as the members being oriented 90 degrees compared to the construction documents, and saved this building from becoming a lesson for engineers.

Prevention
Most buildings are designed with emergency water evacuation in place in case of an overflow or overloading situation. It is a common failure in building roof drains for clogging to occur. According to a personal e-mail correspondence with Jose Vazquez, President of Mainland Construction Company in Miami, Fl, "Emergency overflow scuppers or drains need to be in place to avoid a roof collapse. These usually are set about 4” above the primary drains in case of backup or if there is too much volume of water, this is a life safety issue!" (Jose Vazquez, personal communication, December 1st, 2015)

Water control is an important prevention factor, but this failure was also a direct result of improper construction and engineering practices. The documents were not stamped by a registered engineer, and the building was not even constructed in accordance with the drawings. This collapse could have been prevented by having a structural professional on site during construction. This would have ensured the building was built in accordance with the original design, and would have given the structure much more strength. The re-roofing and patching of the roof during it's 10 year life should have alerted someone to an issue, but the contractors who worked on the fixes simply did the re-roofing without checking the capacity or doing a proper removal of the existing membrane. There were plenty of times when the issue could have been found and fixed. The Steel Joist Institute now has out a steel joist erection and handling paper that covers some of the bracing issues that may have gone wrong during this construction. This paper may have been influenced by collapses, such as these. (Safe Handling and Erection of Steel Joists and Joist Girders, 2007, p 11-17)

Similar Cases
Roof collapses due to ponding or improper roofing replacement are very common and may very well be one of the highest causes of building collapses. A building in Florida collapsed after heavy rains in a very similar situation. Most of the roof caved in on this business complex that was home to a lot of individually leased units. Ten of the units were condemned after the incident. This collapse may have been caused mostly because of the heavy incident of rain that occurred, but it is suspected that there may have been some damage of the units that led to this collapse occurring.

For a video from ABC Action News covering a similar incident in Florida, click the following link: [|ABC News Release of Collapse Information]



Station Square Parking Structure Roof in British Columbia, Canada also collapsed, due to a beam to column connection error. This is similar to the Magic Mart collapse, because there was issues with the connection, along with construction phase issues that were improperly conducted. (Construction Failures, p. 193-197)

Conclusion
The Magic Mart building in Bolivar, Tennessee should not have collapsed, and could have been prevented, such is the situation with most building failures. The initial mistake was attributed to the contractors who built the original building. They did not follow the structural drawings, made incorrect and immoral shortcuts to the construction, which led to an improper bracing scheme and a severely reduced load carrying capacity. This should have been constructed in accordance with the drawings to begin with. As the building proceeded through it's service life, improper roof sloping due to the wrong size structural members had caused ponding for it's entire life, and the leaks were attempted to be fixed, but it only caused more load on the roof and more severe deflections. Thankfully, nobody was killed in this collapse, but one case was filed for an injured shopper, and between the parties involved, they ended up paying out 6 times the monetary amount that the original building cost to build.

Lessons learned in this failure mostly come from the contractors, but also apply to the engineer. Contractors should always keep in mind the structure when adding to it, because it may not have been designed for more loading. Also, completely disregarding the construction drawings is never a correct or moral method of construction. For the firm who designed this, all drawings must be stamped in order to be legal. Many things occurred simultaneously, but the largest factor in the collapse of this building is the contractors who built it improperly, and the contractors who incorrectly fixed the leaking and failing roof. True failure on this building occurred right at the construction phase. According to SGH, The building, had it been built as designed, most likely would not have collapsed.

Annotated Bibliography

 * Bell, G., and J. Parker. "Journal of Performance of Constructed Facilities." //Roof Collapse, Magic Mart// **** //Store, Bolivar, Tennessee: : (ASCE)// . ASCE, May 1987. Web. 06 Oct. 2015.  **


 * This Journal entry is from a paper summarizing the investigation of the Magic Mart building collapse on July 2, 1983 by SGH Inc.


 * Payne, M. (2012) "Roofs - Collapses and Performance Failures" //Failures Wikispaces//  (Nov. 26, 2015).**


 * This Wiki page talks in detail about the types of roof collapses, including ponding, and their effects and mitigation.


 * "The Effects of Ponding Water" //Asphalt Roofing Manufacturers Association// <[]> (Nov. 26, 2015).**


 * Small article about ponding water and its effects, written by Asphalt Roofing Manufacturers Association.


 * Kirby, James (May 1997). "Avoiding Ponding Water by Positive Drainage." Professional Roofing.** **NRCA  (Nov. 26, 2015).**


 * Article with information about how to make and keep positive drainage on a roof.


 * "Roof Caves in on Clearwater Building" //ABC Action News//. (Sept. 28, 2014. <[]> (Nov. 26, 2015).**


 * A similar case where a building in Florida has a roof collapse when a large storm moved through the area.


 * "Weather Underground", <[]> (Dec 10, 2015)**


 * Website accessed to view historical weather information for comparison.


 * Feld, J., and Carper, K. (1997). Construction failure, 2nd Ed., Wiley, New York.**


 * Construction Failures book containing information about the Magic Mart collapse.


 * "Store Roof Collapses in Tennessee; 52 Injured" (1983). Sarasota Herald-Tribune, July 4. (Nov 13, 2015)**


 * Newspaper report of the collapse from the local newspaper.


 * Worthley, W., Pugh, C. and Green, P. "Safe Handling and Erection of Steel Joists and Joist Girders" //Steel Joists Institute.// January 2007 (December 9, 2015)**
 * <[]>**


 * Publication from the Steel Joist Institute about handling and erection practices of joist construction

EXAMPLE:
 * 'Agenda for the Metropolitan Sports Facilities Commission Regular Meeting.' Metropolitan Sports Facilities Commission. Minneapolis, MN: n.p., July 15, 2010. Print.**
 * <[]>**
 * Included in the written agenda is a summary of an inspection of the Metrodome roof structure carried out by Birdair Inc. in April 2010. The summary details the condition of the roof structure at the time, as well as any recommendations by the inspectors. Birdair Inc. was the manufacturer of the original as well as the replacement roof structure of the Metrodome.