To determine the stress state of a wire rope is tedious although analytical solution of a simple rope subjected to static load is available. While facing the problems involving complex ropes, it is usual practice to take approximations based upon the concepts of an average stress state for the constitutive ropes or for every wire. For a statically loaded cable superimposed with a tensile impulse, practically in sudden lifting of a heavy weight, the coupled axial-shearing strain waves in the cable has rarely been studied and explored through analytical approaches. Based on Costello's force-deformation relationship and elastic wave propagation theory, analysis procedures and results are presented in this paper. Time-dependent coupled axial-torsional displacements and axial-shearing strain waves in a simple straight wire rope, due to a longitudinal impact at one end, are obtained. At the instance of the strike, a pair of coupled primary axial-torsional waves is created and begins to travel in the cable independently with different speed. Meanwhile, a coupling induced secondary torsional wave and an axial wave were observed to travel with the primary axial wave and the primary torsional wave, respectively. Phenomenon such as the traveling, reflections from ends, and intersections of the primary waves as well as the secondary wave are presented. Information provided in this paper would be useful in the study of unexpected overstress and/or fatigue problems
Burj Khalifa, a skyscraper in Dubai, UAE, is the tallest man-made structure in the world. Its height reaches 828m but the taller super skyscrapers over 1 km have already been proposed. Tower crane is the key member for building such skyscrapers, which hoists heavy materials from the ground to the top of the construction site. The higher the building rises up, the longer hoist rope is needed and the weight of the rope gives burdens to the tower crane. The steel hoist rope, which was used for Burj Khalifa, weighs 6.32 kg/m and the total weight exceeds 5 tons when the crane climbs up to 800m.The crane has to lift not only the construction materials but also the hanging heavy rope. Therefore, the lighter and stronger hoist rope could provide a breakthrough in hoisting operation in super skyscrapers. A research on a novel hoist rope is on the way utilizing Dyneema, one of the UHMWPE (Ultra High Molecular Weight Polyethylene) fibers. They are the toughest fibers ever made and have usually been used in armor or mooring rope because of its lightweight, soft, and UV resistant property. Replacement of the steel rope with high strength fiber rope made of UHMWPE will reduce the weight of the hoist rope to about one-eighth, thus the load capacity of the tower crane could be drastically increased. This paper describes the design of the fiber hoist rope and the results of some performance tests.
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