Progressive collapse
Encyclopedia
A building undergoes progressive collapse when a primary structural element fails, resulting in the failure of adjoining structural elements, which in turn causes further structural failure
, similar to a house of cards
.
The first date-recorded instance of the term pancake collapse being published in lieu of "progressive collapse" occurred in the August 10, 1980 edition of the New York Times. Fire Chief John Connelly of the 19th Battalion explained that the apartment building, which they responded to in the Bronx, had been weakened by fire to the point that all floors had begun to pancake down on one another. "'It was a pancake collapse.' said Chief John Connelly of the 19th Battalion. 'The entire building was flaming and it went down to the ground.'"
The first date-recorded instance of the term pancake theory being used in reference to a progressive collapse was published in the March 2004 book, "The New Pearl Harbor: Disturbing Questions About the bush Administration and 9/11" by conspiracy theorist David Ray Griffin in which he wrote, "...the other problems in the official "pancake" theory of the collapses, those massive steel columns should have still been sticking up..."
The proposals addressed areas such as increased resistance to building collapse from fire and other incidents, use of sprayed fire-resistive materials (commonly known as "fireproofing"), performance and redundancy of fire protection systems (i.e., automatic sprinklers), fuel oil storage/piping, elevators for use by first responders and evacuating occupants, the number and location of stairwells, and exit path markings.
The model code changes consistent with the NIST WTC investigation recommendations that are now required by the IBC include:
Structural failure
Structural failure refers to loss of the load-carrying capacity of a component or member within a structure or of the structure itself. Structural failure is initiated when the material is stressed to its strength limit, thus causing fracture or excessive deformations...
, similar to a house of cards
House of cards
A house of cards is a structure created by stacking playing cards on top of each other. House of cards is also an expression which dates back to 1645 meaning; a structure or argument built on a shaky foundation or one that will collapse if a necessary element is removed...
.
Timeline of notable examples of progressive collapse
- On July 14, 1902, the 323 foot St Mark's CampanileSt Mark's CampanileSt Mark's Campanile is the bell tower of St Mark's Basilica in Venice, Italy, located in the Piazza San Marco. It is one of the most recognizable symbols of the city....
in VeniceVeniceVenice is a city in northern Italy which is renowned for the beauty of its setting, its architecture and its artworks. It is the capital of the Veneto region...
, ItalyItalyItaly , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
collapsed after its northern load-bearing wall began to separate from the main structure. The cause of the separation was attributed to over 700 years of wear on the structure, including fires, earthquakes, and stress-redistribution, primarily from drying-induced shrinkage on the wooden support beams, the bells themselves swaying back and forth, and Creep (deformation)Creep (deformation)In materials science, creep is the tendency of a solid material to slowly move or deform permanently under the influence of stresses. It occurs as a result of long term exposure to high levels of stress that are below the yield strength of the material....
. No one was injured except for a cat belonging to a caretaker. The tower was a stonemasonryStonemasonryThe craft of stonemasonry has existed since the dawn of civilization - creating buildings, structures, and sculpture using stone from the earth. These materials have been used to construct many of the long-lasting, ancient monuments, artifacts, cathedrals, and cities in a wide variety of cultures...
design.
- On November 1, 1966, the 7 story University of AberdeenUniversity of AberdeenThe University of Aberdeen, an ancient university founded in 1495, in Aberdeen, Scotland, is a British university. It is the third oldest university in Scotland, and the fifth oldest in the United Kingdom and wider English-speaking world...
ZoologyZoologyZoology |zoölogy]]), is the branch of biology that relates to the animal kingdom, including the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct...
Department building in AberdeenAberdeenAberdeen is Scotland's third most populous city, one of Scotland's 32 local government council areas and the United Kingdom's 25th most populous city, with an official population estimate of ....
, ScotlandScotlandScotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
suffered a total collapse while under construction. The collapse was attributed to poor girder welds that were weakened by metal fatigue. The metal fatigue was induced by oscillating lateral forces on the structure (primarily wind). 5 people were killed and 3 others were injured. The building was a steel-frame design and the first known example of the total progressive collapse of a steel-framed building.
- On May 16, 1968, the 22 story Ronan PointRonan PointRonan Point was a 22-story tower block in Newham, east London, which suffered a partial collapse when a gas explosion demolished a load-bearing wall, causing the collapse of one entire corner of the building...
apartment tower in West HamWest HamWest Ham is in the London Borough of Newham in London, England. In the west it is a post-industrial neighbourhood abutting the site of the London Olympic Park and in the east it is mostly residential, consisting of Victorian terraced housing interspersed with higher density post-War social housing...
, LondonLondonLondon is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...
suffered a fatal collapse of one of its corners due to a natural gas explosionGas explosionA gas explosion is an explosion resulting from a gas leak in the presence of an ignition source. The principal explosive gases are natural gas, methane, propane and butane, because they are widely used for heating purposes. However, many other gases like hydrogen, are combustible and have caused...
, which destroyed a load-bearing wall. 4 people were killed and 17 others were injured. The building was a steel-reinforced concrete design.
- On March 2, 1973, the 26 story Skyline Towers Building in Fairfax County, VirginiaVirginiaThe Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...
collapsed as a result of wooden shoringShoringShoring is a general term used in construction to describe the process of supporting a structure in order to prevent collapse so that construction can proceed. The phrase can also be used as a noun to refer to the materials used in the process....
being removed too soon from an upper-story floor during construction. 14 people were killed and 34 others were injured. The tower was a steel-reinforced concrete design.
- On December 19, 1985, the 22 story commercial office building at 1000 Wilshire Blvd, Los Angeles, CA 90017, currently known as the Wedbush Building, experienced a partial collapse of the structure. Construction crews were offloading recently arrived steel girders from a flatbed truck on to the deck of the newly completed 5th floor via crane when a girder broke loose from the crane and fell down on to the current stockpile below, which was already loaded to twice the maximum designed load capacity of the floor. This initiated a progressive collapse of the overloaded floor, causing the floor section and girders to crash through the 4th, 3rd, 2nd, and 1st floors, finally coming to rest in the parking garage. 3 people were killed. The building was a steel-frame design.
- On March 15, 1986, the 6 story Hotel New World in Little India, SingaporeLittle India, SingaporeLittle India is an ethnic neighbourhood found in Singapore that has Tamil cultural elements. Little India lies to east of the Singapore River—across from Chinatown, located west of the river—and north of Kampong Glam. Both areas are part of the urban planning area of Rochor...
collapsed due to a design error when the structural engineer forgot to add the buildings dead load (the weight of the building itself) to his calculations when determining how strong he needed to make the support pillars that held up the building during its construction in 1971. 33 people were killed and 17 others were injured. The building was a steel-reinforced concrete design.
- On March 17, 1987, the 255 foot Pavia Civic Tower in PaviaPaviaPavia , the ancient Ticinum, is a town and comune of south-western Lombardy, northern Italy, 35 km south of Milan on the lower Ticino river near its confluence with the Po. It is the capital of the province of Pavia. It has a population of c. 71,000...
, ItalyItalyItaly , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
collapsed due to 800 years of stress-redistribution on the structure, primarily from drying-induced shrinkage on the wooden support beams, the bells themselves swaying back and forth, and Creep (deformation)Creep (deformation)In materials science, creep is the tendency of a solid material to slowly move or deform permanently under the influence of stresses. It occurs as a result of long term exposure to high levels of stress that are below the yield strength of the material....
. 4 people were killed and 15 others were injured. The tower was a stonemasonryStonemasonryThe craft of stonemasonry has existed since the dawn of civilization - creating buildings, structures, and sculpture using stone from the earth. These materials have been used to construct many of the long-lasting, ancient monuments, artifacts, cathedrals, and cities in a wide variety of cultures...
design.
- On April 23, 1987, the 16 story L'Ambiance PlazaL'Ambiance PlazaThe L'Ambiance Plaza collapse was one of the worst disasters in modern Connecticut history. L'Ambiance Plaza was a 16-story residential project under construction in Bridgeport, Connecticut at the corner of Washington Avenue and Coleman Street. Its partially erect frame completely collapsed on...
in Bridgeport, ConnecticutBridgeport, ConnecticutBridgeport is the most populous city in the U.S. state of Connecticut. Located in Fairfield County, the city had an estimated population of 144,229 at the 2010 United States Census and is the core of the Greater Bridgeport area...
collapsed during its construction phase due to various instances of inadequate shoringShoringShoring is a general term used in construction to describe the process of supporting a structure in order to prevent collapse so that construction can proceed. The phrase can also be used as a noun to refer to the materials used in the process....
that were in use throughout the construction site. 28 people were killed. The building was a lift-slab design.
- In 1992, the ancient bell tower at the medieval church of St Maria Magdalena in GochGochGoch is a town in the district of Kleve, in North Rhine-Westphalia, Germany. It is situated close to the border with the Netherlands, approx. 12 km south of Kleve, and 27 km southeast of Nijmegen.-Cultural ties:...
, GermanyGermanyGermany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
, collapsed. A precise collapse date is not known as the church had been abandoned for some time. The cause was attributed to hundreds of years of stress-redistribution on the structure, primarily from drying-induced shrinkage on the wooden support beams, the bells themselves swaying back and forth in the centuries prior, Creep (deformation)Creep (deformation)In materials science, creep is the tendency of a solid material to slowly move or deform permanently under the influence of stresses. It occurs as a result of long term exposure to high levels of stress that are below the yield strength of the material....
, and weathering on the exposed and unmaintained masonry, including crack enlargement from water freezing and expanding between stones in the winter months, causing further expansion of cracks. No one was injured. The tower was a stonemasonryStonemasonryThe craft of stonemasonry has existed since the dawn of civilization - creating buildings, structures, and sculpture using stone from the earth. These materials have been used to construct many of the long-lasting, ancient monuments, artifacts, cathedrals, and cities in a wide variety of cultures...
design.
- On May 10, 1993, the 4 story Kader Toy FactoryKader Toy Factory FireThe Kader Toy Factory fire was a fire on 10 May 1993 at a factory in Thailand. It is considered the worst industrial factory fire in history. 188 people were killed, and over 500 were seriously injured. Most of the victims were young female workers from rural families...
in Nakhon PathomNakhon PathomNakhon Pathom is a city in central Thailand, capital of the Nakhon Pathom Province. One of the most important landmarks is the giant Phra Pathom Chedi...
, ThailandThailandThailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
collapsed after fire broke out on the first floor and spread throughout the complex. The factory was in full production at the time and all fire exits were locked. 188 people were killed and over 500 others were injured. The building was a steel-frame design.
- On April 19, 1995, the 9 story Alfred P. Murrah Federal BuildingAlfred P. Murrah Federal BuildingThe Alfred P. Murrah Federal Building was a United States Federal Government complex located at 200 N.W. 5th Street in downtown Oklahoma City, Oklahoma, United States. The building was the target of the Oklahoma City bombing on April 19, 1995, which killed 168 people, including 19 children...
in Oklahoma CityOklahoma cityOklahoma City is the capital and largest city of the U.S. state of Oklahoma.Oklahoma City may also refer to:*Oklahoma City metropolitan area*Downtown Oklahoma City*Uptown Oklahoma City*Oklahoma City bombing*Oklahoma City National Memorial...
, OklahomaOklahomaOklahoma is a state located in the South Central region of the United States of America. With an estimated 3,751,351 residents as of the 2010 census and a land area of 68,667 square miles , Oklahoma is the 28th most populous and 20th-largest state...
collapsed due to a truck bomb that was detonated outside of the southern facade. The bombs compression wave caused floors 4 and 5 to shear up and off their columns and collapse on to floor 3. Floor 3 was connected to the main transfer beam, and pulled it inwards when floors 4 and 5 fell on it. This caused all the vertical columns on the southern perimeter that were connected to the transfer beam to collapse as well, along with any floor sections that depended on those columns for vertical support. Similar to the collapse of the World Trade CenterCollapse of the World Trade CenterThe twin towers of the World Trade Center collapsed on September 11, 2001, as a result of al-Qaeda's September 11 attacks, in which terrorists affiliated with al-Qaeda hijacked four commercial passenger jet airliners, flying one into the North Tower and another into the South Tower...
, the Oklahoma City BombingOklahoma City bombingThe Oklahoma City bombing was a terrorist bomb attack on the Alfred P. Murrah Federal Building in downtown Oklahoma City on April 19, 1995. It was the most destructive act of terrorism on American soil until the September 11, 2001 attacks. The Oklahoma blast claimed 168 lives, including 19...
was the first known example of a terrorist-initiated progressive collapse of a building on US soil. 168 people were killed and 680 others were injured. The building was a steel-reinforced concrete design.
- On June 29, 1995, the 5 story Sampoong Department Store in SeoulSeoulSeoul , officially the Seoul Special City, is the capital and largest metropolis of South Korea. A megacity with a population of over 10 million, it is the largest city proper in the OECD developed world...
, South KoreaSouth KoreaThe Republic of Korea , , is a sovereign state in East Asia, located on the southern portion of the Korean Peninsula. It is neighbored by the People's Republic of China to the west, Japan to the east, North Korea to the north, and the East China Sea and Republic of China to the south...
collapsed as a result of poor building standards. 501 people were killed and 937 others were injured. The complex was a steel-reinforced concrete design.
- On September 11, 2001, World Trade CenterCollapse of the World Trade CenterThe twin towers of the World Trade Center collapsed on September 11, 2001, as a result of al-Qaeda's September 11 attacks, in which terrorists affiliated with al-Qaeda hijacked four commercial passenger jet airliners, flying one into the North Tower and another into the South Tower...
buildings 1, 2 and 7 in New York CityNew York CityNew York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...
, collapsed as a result of terrorist attacks and the subsequent fires that followed. In response to the WTC event, the National Institute of Standards and TechnologyNational Institute of Standards and TechnologyThe National Institute of Standards and Technology , known between 1901 and 1988 as the National Bureau of Standards , is a measurement standards laboratory, otherwise known as a National Metrological Institute , which is a non-regulatory agency of the United States Department of Commerce...
conducted a 3-year building and fire safety investigation to study the factors contributing to the probable cause (or causes) of post-impact collapse of the WTC Towers (WTC 1 and 2) and WTC 7. NIST subsequently expanded its research in areas of high-priority need such as prevention of progressive collapse, fire resistance design and retrofit of structures, and fire resistive coatings for structural steelStructural steelStructural steel is steel construction material, a profile, formed with a specific shape or cross section and certain standards of chemical composition and mechanical properties...
. 2,752 people died in the buildings, including 157 passengers and crew members who were aboard two hijacked airplanes that struck buildings 1 and 2, initiating fires in both, with debris initiating fires in building 7 upon the collapse of buildings 1 and 2. The buildings were a steel-frame design.
- On February 12, 2005, the 28 story Windsor Tower in MadridMadridMadrid is the capital and largest city of Spain. The population of the city is roughly 3.3 million and the entire population of the Madrid metropolitan area is calculated to be 6.271 million. It is the third largest city in the European Union, after London and Berlin, and its metropolitan...
, SpainSpainSpain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
suffered the collapse of the upper 11 floors of the building. The tower had a reinforced concreteReinforced concreteReinforced concrete is concrete in which reinforcement bars , reinforcement grids, plates or fibers have been incorporated to strengthen the concrete in tension. It was invented by French gardener Joseph Monier in 1849 and patented in 1867. The term Ferro Concrete refers only to concrete that is...
inner core surrounded by a traditional webbed steel-frame outer-perimeter. Between floors 16 and 17 was a 7 foot thick, reinforced concrete transfer floor, designed to act as a bulkheadCompartmentalization (fire protection)Compartmentalization in structures, such as land-based buildings, traffic tunnels, ships, aerospace vehicles, or submarines, is the fundamental basis and aim of passive fire protection....
and to support the steel framework of the upper 11 stories. An office fire began on the 21st floor and after 5 hours, the concrete inner-core could no longer support the melting steel outer-framework. The upper 11 stories collapsed down to street level with remnants of the upper 3 floors collapsing down on to the transfer floor. No one was killed. The building was a composite steel-frame and steel-reinforced concrete design.
Synonyms of progressive collapse and their origins
Since the resulting damage in a progressive collapse is disproportionate to the original cause, the term disproportionate collapse is frequently used in engineering to describe this collapse type.The first date-recorded instance of the term pancake collapse being published in lieu of "progressive collapse" occurred in the August 10, 1980 edition of the New York Times. Fire Chief John Connelly of the 19th Battalion explained that the apartment building, which they responded to in the Bronx, had been weakened by fire to the point that all floors had begun to pancake down on one another. "'It was a pancake collapse.' said Chief John Connelly of the 19th Battalion. 'The entire building was flaming and it went down to the ground.'"
The first date-recorded instance of the term pancake theory being used in reference to a progressive collapse was published in the March 2004 book, "The New Pearl Harbor: Disturbing Questions About the bush Administration and 9/11" by conspiracy theorist David Ray Griffin in which he wrote, "...the other problems in the official "pancake" theory of the collapses, those massive steel columns should have still been sticking up..."
Model code changes
Based on recommendations from the Commerce Department's National Institute of Standards and Technology (NIST), a comprehensive set of building code changes were approved by the International Code Council (ICC). The recommendations were based on the findings of NIST's three-year investigation of the collapses of New York City's World Trade Center (WTC) towers on Sept. 11, 2001.The proposals addressed areas such as increased resistance to building collapse from fire and other incidents, use of sprayed fire-resistive materials (commonly known as "fireproofing"), performance and redundancy of fire protection systems (i.e., automatic sprinklers), fuel oil storage/piping, elevators for use by first responders and evacuating occupants, the number and location of stairwells, and exit path markings.
The model code changes consistent with the NIST WTC investigation recommendations that are now required by the IBC include:
- Increased bond strength for fireproofing (nearly three times greater than previously required for buildings 75–420 feet in height and seven times greater for buildings more than 420 feet in height).
- Field installation requirements for fireproofing to ensure that:
- installation complies with the manufacturer's instructions;
- the substrates (surfaces being fireproofed) are clean and free of any condition that prevents adhesion;
- testing is conducted to demonstrate that required adhesion is maintained for primed, painted or encapsulated steel surfaces; and
- the finished condition of the installed fireproofing, upon complete drying or curing, does not exhibit cracks, voids, spalls, delamination or any exposure of the substrate.
- Special field inspections of fireproofing to ensure that its as-installed thickness, density and bond strength meet specified requirements, and that a bonding agent is applied when the bond strength is less than required due to the effect of a primed, painted or encapsulated steel surface. The inspections are to be performed after the rough installation of mechanical, electrical, plumbing, sprinkler and ceiling systems.
- Increasing by one hour the fire-resistance rating of structural components and assemblies in buildings 420 feet and higher. (This change was approved in a prior edition of the code.)
- Explicit adoption of the "structural frame" approach to fire resistance ratings that requires all members of the primary structural frame to have the higher fire resistance rating commonly required for columns. The primary structural frame includes the columns, other structural members including the girders, beams, trusses, and spandrels having direct connections to the columns, and bracing members designed to carry gravity loads.