Common Root Causes in Recent Failures of Cranes

A. MARQUEZ; P. VENTURINO; J,L. OTEGUI

La Haya

Conferencia; ICEFA 5, 5th Int. Conf. on Eng. Failure Analysis; 2012

The catastrophic failure of cranes, being used in the construction of buildings and forcargo movement in ports and ships, is a potentially very dangerous event and has often fatal consequences. There are about 100 annual falling events, with a fatality rate of one per accident.The causes are varied, but most fallsare due to harsh weather, structural deficiencies, overload and errors duringdismantling of these structure. The causes of two fallen cranes are discussed in this study; one crane used for constructing buildings and the other for handling port cargo. Both cranes have conceptually different designs. One balances the tower moments with calculated counterweights to optimize the loads in the structural elements in fully loaded and unloaded states; the other one is designed without counterweights and transmitsall operational loads to the base. While both cases are totally different, common root causes can be identified in both case studies that aim at the design and construction of theirbases. Striking similarities in failure circumstances are discussed in this study. These include errors in the identification and interpretation of previous symptoms, in the mitigation measures undertaken and in the risks, assumed by personnel, due tolack of information and training.The cranes are constituted by slender structures subjected to large loads that generate reversed stresses in the bases. Very often the effects and implications of variable loads are not completely understood or valued by builders and operators, which areused to deal with intrinsically static loads. A normative gap in the identification of responsibilities deriving from the equipment rent or sale contracts is also identified. There is responsibility transference in these contracts to the owner or main contractor on the site, concerning design and execution of base works.