Ship-to-shore (STS) container gantry cranes, used at terminals for loading and unloading containers from a ship, are an important part of harbor structures. e size and weight of modern STS container cranes are increasing to satisfy the demand for bigger ships. is is expected to result in more lateral load when excited by seismic motions. e existing Korean STS container cranes did not behave properly during several recent moderate earthquakes in South Korea. Typical Korean STS container cranes must be checked for the earthquake-resistant capacity. In this research, two nonlinear static analyses procedures, also known as pushover analyses, commonly used for seismic design of buildings, namely, capacity spectrum method and equivalent linearization method, are comprehensively studied to check their suitability for studying seismic behavior of STS cranes. Results obtained by these two nonlinear static analysis methods are then compared with the results obtained by nonlinear time-history analyses of the STS cranes by exciting them with nine recorded earthquake time histories around worldwide. e behaviors of the cranes are analyzed in terms of the total base shear, drift, and base uplift. e comparisons indicate that the nonlinear static methods can be appropriate for estimating the total base shear and drift of the portal frame of a container crane. e pushover analyses also provide information on performance levels as defined in ASCE/SEI 41-13, of a typical Korean STS container crane. Furthermore, it is observed that the uplift response of the crane is strongly influenced by the duration of an earthquake.

Ship-to-shore (STS) container cranes are important pieces of equipment in container terminals for container handling, so they need to be properly designed to avoid damage or collapse due to natural hazards (i.e., storms or earthquakes). However, the dynamic analyses necessary for this can be cost- and time-consuming because of the need to consider the time history of ground motions and several sources of uncertainty. Thus, sensitivity analysis on the input parameters to the responses of the structures is needed to categorize which sources of uncertainty are significant enough to be considered as random variables. In this study, an investigation is carried out into the sensitivity of some sources of uncertainty to the seismic response of a Korean container crane structure. The input random variables studied include ground motion intensity, ground motion profiles, mass, damping, and elastic modulus of steel. Nonlinear dynamic analyses are conducted using a set of 20 natural ground motions scaled to three ground motion intensity levels, in compliance with the Korean Design Standard. The method of deterministic sensitivity analysis using the so-called tornado diagram is applied for the evaluation of structural systems. For the studied type of Korean container crane, it can be stated that the intensity of ground motions (i.e., spectral acceleration) is the most significant input parameter on the response of the structure, as measured in terms of portal drift, vertical reaction of the crane’s legs, and total base shear. The next most significant influencing factors are the mass of the structure and the characteristics of every ground motion. Damping plays a relatively important role on the total base shear, while it shows almost no impact on the axial reaction of the crane’s legs. Of the three engineering design parameters (portal drift, vertical reaction, and total base shear), the elastic modulus exhibits a low effect, but it should be considered a source of uncertainty in seismic analysis.

In recent years, several large earthquakes have caused the collapse of container cranes, which have resulted in halting of freighting, and significantly affected the economy. Some reports are concerned the uplift and derailment events of crane legs, and the collapse of the crane itself. In this study, the effects of different boundary conditions used in the numerical method are investigated for a container crane under seismic excitation. Three different boundary conditions are considered in terms of the connection of the crane’s legs (wheels) and the ground (rails), namely pin support (PIN), gap element (GAP), and Friction contact (FC) elements, by using the SAP2000 program for a typical container crane. Then, time history dynamic analyses are conducted using nine recorded ground motions. Dynamic behaviors of the container crane are studied in terms of the total base shear, portal drift, and relative displacement of legs, by investigating the three types of base boundary conditions. The results of the study show that when the intensity of earthquakes is large enough to create uplift and derailment events, the selection of the boundary condition model considerably affects the dynamic responses of the container crane. In addition, when uplift and derailment of the crane occur, the FC support condition is the most compatible with the real behavior of the crane. On the other hand, under low seismic excitation, there is no significant difference of the crane behavior according to the choice of boundary condition model.

In this study, the seismic response of a container crane under near-field and far-field ground motions was investigated using a shaking table test on a 1/20 scale crane. The 1/20 scale crane was designed and fabricated based on the similitude laws, in which three independent quantities: geometric length, acceleration, and elastic modulus, were used to design the 1/20 scale crane. A series of shaking table tests were conducted at the Seismic Research and Test Center, Pusan National University, Yangsan Campus to evaluate the seismic response of the scale crane under near-field and far-field ground motions. The results show that the near-field ground motions can cause larger internal forces (that is, axial force and two bending moments) in the landside and seaside legs and larger portal drift than the far-field ground motions. The portal drift of the container crane subjected to the near-field ground motions was 43% higher than that of the container crane subjected to the far-field ground motions. Furthermore, when subjected to the near-field ground motion, the bending moment in the crane's portal leg was 37% higher than the bending moment when the crane was subjected to the far-field ground motions.

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