Last week marked the 30th anniversary of the first documented LODD in a lightweight truss. Very little is written about this significant fire. Our thanks to TSL member FrankL who put together an informational drill sheet to share with all members of The Secret List – to further understand the history of the dangers of truss.
Lightweight Truss Significant fire 30th Anniversary
According to Vincent Dunn (Collapse of Burning Buildings), the first known firefighter to be killed in a collapse of a light weight wood truss building was James Pressnall of the Irving (Texas) Fire Department. His death occurred on February 27th 1984. This is 30 years ago last Monday- week ago today. Firefighter Pressnall was killed in the Line of Duty when a lightweight wood truss collapsed on him while operating in a two story apartment house fire. FF Pressnall, age 31, died of second and third degree burns over 70% of his body, and smoke inhalation, which he sustained in the roof collapse at this fire .
In yet another example, 2 Firefighters were killed in the Line of Duty when a collapse of a lightweight wood truss roof collapsed and trapped the Firefighters. They were working an arson fire in a church in Memphis Tennessee. The collapse occurred only seven minutes after the arrival of firefighters. It happened at the Pilgrims Hope Baptist Church at 3084 Woodrow Street at 1:58 p.m. on December 26, 1992.
HERE is that report:
YOU KNOW THIS!
Firefighters may be injured and killed when fire-damaged roof and floor truss systems collapse, sometimes without warning.
DO YOU KNOW THESE FIRES, THESE FALLEN FIREFIGHTERS?
=Todd Aldridge and Mark Benge-Orange Co, FL 1998
=Alan Michelson, Gillette, WY-1990
=James Hill & Joseph Boswell Memphis, TN-1993
=John “Strawn” Nutter, Louisville, KY 1994
=John Hudgins & Frank Young, Chesapeake, VA-1996
=Edward Ramos, Branford, CT-1996
=Brant Chesney, Forsythe Co, GA 1996
=Gary Sanders, Brian Collins & Philip Dean, Lake Worth TX 1999
=Lewis Mayo & Kimberly Smith-Houston, TX 2000
=John Ginocchetti & Tim Lynch, Manlius, NY 2002
=Cyril Fife & Kevin Olson, Yellowknife, CN 2005…
and there are many more….
According to the United States Fire administration (USFA Firefighter Fatalities) during the period from 1990-2000 structural fires and explosions accounted for 46.1% of firefighter fatalities. This number represents five hundred firefighters in a ten year period. During the period of 1998-2003 The National Institute for Occupational Safety and Health (NIOSH) identified at least twenty fatalities and twelve injuries that occurred during firefighting operations in buildings containing truss systems, of which more then half were in lightweight wood truss buildings.
According to the Wood Truss Council of America, (WTCA) wood trusses are used in roof systems in more then sixty percent of all building in the United States.
The definition of lightweight construction as defined by NIOSH is a structural member joined together by a rigid framework. They are most often in the shape of triangles. The unique characteristic of a truss is the inherent stability of the triangle. The design of a truss which separates compressive and tensile stresses, allows for a minimum of materials to be used, resulting in an economic benefit for the builder.
Firefighters are taught that a lightweight wood truss will collapse in a fire in only five to ten minutes. This is also about the same time that Ffirefighters begin arriving on the scene.
Engineers, whom formally would overbuild a bearing element of a building, are now capable of determining the exact failure point. This engineering enables a builder to save money by eliminating costly overbuilding. They can erect a structure which is capable of supporting the anticipated weight load of the structure plus the anticipated weight inside the building. Engineered building components may provide adequate strength under normal conditions, but under fire conditions these truss systems can lead to collapse. The trouble with this thinking is the engineers failure to take into account the affect that a fire will have on one of these structures.
The significant factors in this incident include the short time that a lightweight wood truss roof structure can be expected to maintain its structural integrity when involved in a fire and the lack of warning indicators of pending collapse. This quote was taken directly from the investigation report from this fire. (Wood Truss Roof Collapse, Memphis) This fire occurred in 1992, more then twenty years ago.
Trusses come in many sizes, shapes, and design. It is important that fire fighters are able to identify them and the dangers they may pose. Trusses generally consist of wood but may also be constructed with other types of metals. All the materials may act differently under fire conditions, but all are subject to failure.
Know your buildings and operate accordingly.
RELATED LINKS TO THE ABOVE:
FIREFIGHTER DEATH & INJURY: TRUSS CONSTRUCTION FAILURE:
ENTER THRU THE DOOR-FALL THRU THE FLOOR: