Big Dig Tunnel Collapse:
A 38 year old woman was killed when a section of the concrete suspended ceiling in the Interstate 90 (I90) connector tunnel in Boston, Massachusetts detached from the tunnel roof and fell onto her vehicle.
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Silk Air 185 Aircraft Accident:
On December 19, 1997 a Silk Air Boeing B737-300 aircraft departed Soekarno-Hatta International Airport, Jakarta with 97 passengers, 5 cabin crew and 2 cockpit crew. The aircraft took off in daylight with good weather conditions and climbed to 35,000 feet. The aircraft suddenly dropped 400 feet in 8 seconds and continued in a rapid descent initiating in-flight breakup followed by complete disintegration of the aircraft upon impact with the Musi River. All 104 persons on board were killed. Although 73% of the wreckage was recovered, most of the samples consisted of small highly distorted parts.
Rapperport Associates was engaged to develop a simulation of the final flight path based on flight recorder data, radar information and debris field scatter.
Pedestal Collapse
Tullio Lombardo’s statue of Adam was the centerpiece of the Metropolitan Museum of Art’s newly installed Renaissance exhibit. Carved around 1490 for the tomb of the Doge of Venice, purchased by the Museum in 1936, it was their most important Italian Renaissance sculpture and one of the most important Italian sculptures outside Italy. On October 6, 2002 after the museum had closed for the evening, guards discovered the sculpture shattered on the marble floor. The pedestal designed to support the sculpture had collapsed sending the prized sculpture crashing to the floor. The value of the sculpture was estimated at $40 to $80 million.
Rapperport Associates was retained to conduct a failure analysis of the pedestal.
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Pallet Rack Collapse
A massive pallet racking system used by R. R. Donnelly Corporation to store printed catalog matter suddenly collapsed resulting in the complete destruction of the pallet racking system and loss of the stock. The facility consisted of 12 racks, each 66 feet high (10 bays) and 228 feet long. Although the property loss was substantial, amazingly, no one was injured. Some failed welds were observed in the wreckage and there was a question whether weld failure precipitated the collapse or whether the welds failed as a result of the severe structural deformation associated with the collapse.
Rapperport Associates was retained to determine the cause of the failure. A buckling analysis indicated that the structure was overly flexible structure due to inadequate cross bracing and failure was caused by global buckling. A stress analysis of failed welds confirmed that weld failure resulted from the high loads of the collapsing structure and were not the initiating events.
Scaffolding Collapse
One worker was killed and a co-worker was seriously injured when the tower climbing work platform they were working from collapsed sending them plummeting 85 feet to the ground below. A third worker managed to escape injury by leaping over the parapet onto the building’s roof. The workers were removing water table stone from the roof façade of an eight story building when the accident occurred. A bay window protrusion extending the full eight stories of the building hindered worker access to the building directly from the central work platform. Cantilever extensions had been bolted to the central work platform to accommodate the bay window protrusion.
Rapperport Associates was engaged to determine the cause of the failure. Finite element stress and buckling analyses were conducted and verified with full scale testing. It was determined that the structure failure by buckling and not as a result of weld failure.
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Roof Truss Failure
A worker sustained serious head injury when an 80 foot wooden truss fractured during building construction and struck him. A reconstruction of the rigging configuration combined with a dynamic finite element stress analysis of the truss stresses generated during construction showed that the failure occurred from improper rigging when the truss was being lifted into position and not as a result of a defect.
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Polymer Degradation – Deterioration of Celcon Plastic Water Pipe Fittings:
Our firm was selected as experts for the insurance defense group in Hoechst Celanese Corp. vs. National Union Fire Insurance Company et. al. This matter related to the premature field failure of residential plastic pipe fittings throughout the southern and western regions of the United States and involved losses of hundreds of millions of dollars. Our firm was engaged to determine if premature fitting failures would be expected based on the available file documents. We inspected failed fittings, performed stress analyses, analyzed file test data, and reviewed thousands of documents to assess whether or not Hoechst Celanese knew or should have known that the fittings were unlikely to survive the intended service life expectancy prior to releasing the product.
Acetal resins are sensitive to chorine and low levels of chlorine in potable water supplies (1-3 ppm) can be sufficient enough to promote stress corrosion cracking. Widespread failure of acetal fittings in potable and hot water supplies resulted in one of the largest class action lawsuits in the US when acetal plumbing fittings cracked and caused flooding of homes. The accompanying photograph illustrates chlorine attack in the threaded portion of an acetal fitting. Chlorine attack caused the material to become brittle and resulted in crack initiation at the thread roots. The discoloration on the fracture surface was caused by deposition of carbonates from the hard water supply, indicating that the joint had been partially cracked for a while prior to component failure.
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