The seismic behavior of port container cranes has been largely ignored---by owners, operators, engineers, and code officials alike. This is despite their importance to daily port operations, where historical evidence suggests that port operational downtime following a seismic event can have a crippling effect on the affected local, regional, and national economies. Because the replacement time in the event of crane collapse can be a year or more, crane collapse has the potential to be the "critical path" for post-disaster recovery. Since the 1960's, crane designers allowed and encouraged an uplift response from container cranes, assuming that this uplift would provide a "safety valve" for seismic loading; i.e. the structural response at the onset of uplift was assumed to be the maximum structural response. However, cranes have grown much larger and more stable such that the port industry is now beginning to question the seismic performance of their modern jumbo container cranes.;This research takes a necessary step back, and reconsiders the fundamental effect that uplift response has on the seismic demand of portal-frame structures such as container cranes. One primary objective of this work is to develop methodologies for realistically modeling this effect, and to serve as a foundation for the design and evaluation of new and existing container cranes. Portal uplift theory, derived here to meet that objective, is a major contribution. Using this unique new theoretical tool to estimate the dynamic structural demand during seismically-induced uplift events, the "safety valve" design assumption for container cranes is found to be unconservative. With implications to all structures which exhibit reduced shear stiffness during uplift events, portal uplift theory is verified with detailed finite element models incorporating frictional contact elements and experimental shake-table testing of a scaled jumbo container crane allowed to uplift.;Understanding that container cranes may be subjected to higher seismic demands than expected, characterizing their risk is critical. Thus, using the verified models developed in this work, fragility curves and downtime estimates are developed for three representative container cranes to provide insight into their seismic vulnerability. These fragility curves are conditional probability statements which describe the potential for exceeding certain damage thresholds during an earthquake of a given intensity. Throughout the analysis, appropriate levels of uncertainty and randomness are evaluated and propagated. Because the damage levels are defined globally and according to specific repair models, probabilistic estimates of the operational downtime due to a given earthquake are also developed. The results indicate that existing container cranes, especially stout cranes and those not specifically detailed for ductility, are not expected to achieve the seismic performance objectives of many ports. Due to their potential for damage and/or collapse, container cranes designed using previous and current standards can significantly contribute to port seismic vulnerability. To address this deficiency, performance-based design recommendations are provided which encourage the comparison of demand and capacity in terms of the critical portal deformation, using the derived portal uplift theory to estimate seismic deformation demand. Simplified methods and basic design factors are proposed and demonstrated which enable practitioners to conveniently design for reliable achievement of seismic performance objectives.
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