2 Agenda Brief history of testing and Special Inspection Notable past failuresNotable present-day failuresLess dramatic, but more common failures
3 Materials Testing, A Brief History Post-Civil War: engineers identify the need to better understand physical properties1870’s: Riehle Brothers manufacture compression testing machines1880: Tinius Olsen invents the Little Giant universal testing machineFirst, a very brief history of materials testing and Special Inspection.Testing different construction materials has been around in some form or fashion for centuries. The Romans conducted load tests of various structures to determine what would stand the test of time. Mortar for use in Medieval cathedrals were tested. Wooden pipes were tested in the early 19th century. But it was not until after the Civil War that engineers really began to experiment with, and test, materials used in construction.In the 1870’s the Riehle (pronounced “real”) Brothers made and sold compression machines for testing the compressive strength of materials. One of their employees was named Tinius Olsen, and he was fired at the end of the decade because he was too progressive and wanted to expand the Riehle line, while the brothers did not. So, Mr. Olsen went out on his own, and invented the “Little Giant”. This was the world’s first universal testing machine (a machine that could test things in both compression and in tension – not at the same time). Tinius Olsen went on to invent and perfect many other things for testing materials, and his company is still in existence today.
4 Materials Testing, A Brief History 1898: American Society for Testing and Materials is formed to address frequent breaks in rail lines1901: A1 standard on steel rails1909: first cement and concrete standards1920’s: first road and paving standards1930’s: first masonry standards1930’s: first soil standardsIn the late 19th century, the railroad industry was experiencing many failures with their rails, so a group of rail engineers got together and formed the American Society for Testing and Materials – ASTM. Three years later they published their first standard – A1 on steel rails. This standard is still in existence and use today, and hundreds more “A” standards have been created on steel.The beginnings of the “B” standards followed, and these are all on non-ferrous metals. Next came the “C” standards on cement and concrete. With the advent of the automobile, and its rapid rise to prominence, the 1920’s saw many standards created for that area of engineering and testing. Masonry standards first began to appear in the 1930’s, followed by standards on soil.Intermixed with all of these were many other standards, such as ones on roofing and waterproofing materials, and sealants, and ASTM continues to update and create new standards today.
5 Skyline Towers, Arlington, VA, 1973 14 people dieCaused by removal of shoring before adequate concrete strength is reachedConstruction was evolving, and new construction processes and materials were being used each year. But all of a sudden the country experienced a number of very public and notable failures. This started with the 26-story Skyline Tower condominium building collapse in Arlington, Virginia. Arlington is right across the Potomac River from Washington, D.C., so this failure was highly visible and seen by many congressmen. The failure was caused by removing shoring too quickly in the building, and before concrete could reach strengths adequate to support the structure, and 14 people died as a result.
6 Hartford Civic Center Roof Collapse, 1978 Caused by design and construction changesSpace Frame Roof DetailThe roof of this building is a “space frame” construction, with many welded connections of light-gauge metal components. During a large snow storm in 1978 part of the roof collapsed, just hours after the building was packed to capacity for a U. of Conn. men’s basketball game. It was determined this was caused by design and construction changes that were not properly reviewed.
7 Angle Connection Details Hartford Civic CenterAngle Connection DetailsAs DesignedAs you can see in these diagrams, the roof connections were originally designed to hold significantly more load than what was actually constructed. As constructed, some of these connections held less than 10% of what they were originally designed for!As Built
8 Kemper Arena Roof Collapse, Kansas City, 1979 Caused by inadequate roof drainsPonding water on roofMiscalculated hanger bolt strengthsThe roof of this building was designed to pond water during large storms, and then release the water slowly into the sewer system. This was done because the sewer system in the neighborhood was antiquated and did not have the necessary capacity to handle large water flows. However, the roof hanger bolt strengths were miscalculated, and during a large storm in 1979 one bolt gave way, followed by numerous others in a “zipper” fashion, causing more than an acre of the roof to collapse.Interestingly, the American Institute of Architects had given the building an award for its design and construction when it was completed, and thousands of its members were at its annual national conference there less than 24 hours before the 1979 collapse.
10 Hyatt Regency Skywalk Collapse, Kansas City, 1981 114 people dieCaused by construction changes without engineering reviewBut the big failure that became the focus of changes in the testing and inspection world was the 1981 collapse of two skywalks at the Kansas City Hyatt Regency Hotel.On the day of the disaster, a dance competition was being held in the hotel atrium. About 1,600 people had gathered to watch, including hundreds of people on the elevated walkways and underneath them on the main floor. The failure occurred when steel rods the 4th floor walkway was supported by pulled out of the steel support beam they were attached to, and the walkway collapsed onto the 2nd floor walkway, which was directly below. This caused the 2nd floor walkway to also collapse onto the main floor. The result was 114 people dead and hundreds more injured, about 200 of them critically injured.The investigation into the collapse found that the contractor could not attach the steel support rods as the design drawings indicated, so they made adjustments in the field. However, these changes were never reviewed by the structural engineers, which proved disastrous.
11 U.S. House Sub-Committee on Science and Technology 1982 studies structural failures1984 presents report of findings• Need for improved communications during the construction process• Need for construction inspection
12 L’Ambiance Plaza, Bridgeport, CT, 1987 28 people dieStacked slab constructionUnknown exact cause
13 and…..Special Inspections is Born 1988 Special Inspections adopted in BOCA2000 Chapter 17 of the IBC was created from the legacy codes (UBC, BOCA, SBC)+=
14 IBC, Section 1704 – Special Inspections Required by codeSpecial Inspector must be qualifiedSpecial Inspector must be approved by the Building OfficialSpecial Inspector must be hired by the owner or his direct representative (such as SE or architect)
15 World Trade Center Collapse, 2001 2,752 people dieSubstandard fireproofing is a major contributorThese buildings were completed in 1970 and 1971, and were supposed to have 2-hour and 3-hour fire ratings, depending on the area of the building. It was known for some time that the fireproofing materials were not up to code, with many areas lacking proper thicknesses and inferior adhesion to the steel. During various tenant improvements and other construction activities over the succeeding decades, areas of fireproofing were removed and/or disturbed, any many of these areas were never renovated or corrected. Also, it is suspected that when the terrorist planes crashed into the buildings the explosions knocked fireproofing off of the steel. All of this greatly exacerbated the problems with the explosions and resulting fires, and the South Tower collapsed after burning for only 56 minutes and the North Tower collapsed after burning for 102 minutes.
16 McGuire Apartments, Seattle, Built 2002 Improperly sealed PT cablesCorroded cables, cracked concrete, structural integrity of entire structure compromisedDemolished in 2011This 25-story apartment building was constructed in Seattle in After about 6 years it was discovered that the ends of the post-tension cables used to reinforce each floor slab had not been properly sealed and corrosion was rapidly causing serious structural problems. It was subsequently determined that it would be more expensive to fix the problems than it would be to take the building down and reconstruct it. The building was demolished in The contractor, their quality control personnel, and inspectors associated with this project were raked over the coals, with the contractor finally having to footing the bill to replace the building
17 I-35 Bridge Collapse Minneapolis, 2007 13 people dieUnder-designed gusset platesWeight from additional 2” deck concrete (>5 million lbs.)578,000 lbs. construction equipment and materialsThis bridge opened in 1967 and was a major traffic artery into downtown Minneapolis. During the evening rush hour on August 1st it suddenly collapsed. The investigation of the collapse determined the primary cause was under-sized gusset plates used at the beam-column connections. Contributing to that error was the fact that 2 inches of concrete had been added to the road surface over the years, increasing the dead load by 20%. At the time of the collapse the bridge was undergoing remedial work, and the extraordinary weight of construction equipment and material resting on the bridge just above its weakest point also contributed to the collapse. That load was estimated at 578,000 pounds consisting of sand, water, and vehicles.
18 Harmon Tower, Las Vegas “Completed” in 2008 Missing critical rebar Reduced from 49 to 28 storiesScheduled for demolition
19 Block 7, Lotus Riverside, Shanghai, 2009 1 person diesThis failure was caused by saturated soil (infiltration from the adjoining canal) reducing the soil bearing pressure and a foundation system that was not designed for such conditions. Exacerbating the situation, the construction firm began excavating a subsurface parking area directly adjacent to the building without any support provided to the structure. 7 engineers and inspectors were arrested after this failure, and one of them was executed!Unsupported garage excavationSaturated soils
20 Indiana State Fair Stage Collapse, 2011 7 people dieInsufficient wind supportThis stage was supported by guy lines that tied off to K-rail type concrete blocks that were not anchored to the ground. They resisted loading only by friction with the ground and through their own weight. This design was sufficient to resist wind loads up to mph, depending on wind direction, however, the fair experienced peak wind gusts of 59 mph, which caused the stage to collapse onto the spectators.