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Gantry cranes are customized to meet specific requirements at a facility. Due to their unique configuration, prescriptive design, based on empirical rules, cannot be justified. Gantry cranes have some brittle elements (joints and connections) and some ductile elements (steel beams and columns). Brittle elements should be made stronger than the ductile elements to allow the ductile elements to yield, deform, and dissipate energy during seismic ground shaking. The deformation demands on ductile elements can be reduced by increasing their strength, but the brittle elements should always be stronger than the ductile elements. Due to their geometry, gantry crane models are nonlinear even when the structural members remain elastic. Therefore, linear analyses are omitted in this chapter. As in the case of liquid-storage tanks, discussed in Chap. 8, gantry cranes are fairly complex systems. Therefore, nonlinear-dynamic analyses are not practical for gantry cranes. In this chapter, both elastic and inelastic analyses are carried out by the nonlinear-static procedure. |
