## 1 Introduction  
Container ports in seismically active regions all over the world are vulnerable to severe damage from earthquakes. The risk can have considerable economic impacts on the affected regions. However, container ports generally do not receive similar attention in comparison with other infrastructure systems such as buildings, bridges, and water and power plants [1]. One of the most critical but vulnerable components in the operation of a port is the container crane used for loading and unloading containers from ships. Modern jumbo container cranes may weigh between 1300 and 1800 tons. They are capable of lifting containers weighing between 60 and 120 tons to heights between 35 and 42 m above the wharf (or gravity quay wall) [2,3]. The rail gage/span and portal clearance are designed to adapt to traffic lane widths. A typical portal width is approximately 30.5 m, and it can accept four working traffic lanes. Figure 1 illustrates an example of the Korean A-frame single hoist Ship-to-Shore (STS) container crane. In South Korea, the seismic performance of the container crane has not been considered for most of the port design guidelines in the past, because South Korea was expected to be less severely affected by earthquakes. However, strong shaking occurred recently, i.e., the 5.4-magnitude Pohang earthquake on 15 November 2017 [4], and the 5.8-magnitude Gyeongju earthquake on 12 December 2016 [5], which damaged several buildings, port facilities, roads, and bridges. Thus, it is of utmost importance to consider the seismic analysis for a container crane to reduce the economic and human losses due to earthquake. Historically, many ports have been partially destroyed by earthquakes, e.g., the port of Kobe (Japan) in 1995 [6], port in Port-au-Prince (Haiti) in 2010 [1], and port in Chile in 1985 [7], requiring a long time for repair and recovery. When a container crane completely collapses, it typically takes 12-24 months to purchase a new port crane [8]; thus, pre-defined damage levels and structural performance are necessary in the seismic performance evaluations of new and existing cranes to predict their risks. Fragility analysis is a key input parameter for the seismic risk assessment of a structural component or entire system, and enables the evaluation of the potential damage thresholds and specific repair models of a structural component in a system during a predefined intensity earthquake [1]. The fragility curve, which is usually assumed to be a cumulative distribution function (CDF) [9], was first applied to civil infrastructures in ATC-13 in the mid-1980s [10] and was later applied to many types of structures such as bridges [11, 12], highways [13], buildings [14], tunnels [15, 16], and ports [1, 17]. Fragility assessment for the container crane has not been widely studied. A significant study was conducted by [PERSON] et al. [1, 18]. Three two-dimensional (2D) numerical models of American cranes, i.e., J100, LD100, and LD50, were considered with overall limit states obtained in terms of critical portal deformations. Based on previous experimental and numerical studies, hysteretic rotational springs were utilized to capture both elastic and inelastic behavioral features. In addition to earthquake excitation, fragility assessment owing to stochastic wind loading was also considered for container cranes [19]. In this study, a three-dimensional (3D) finite element (FE) model of a typical Korean container crane was used in the fragility analyses. The damage or limit states were defined in terms of portal drift using nonlinear static analysis with plastic hinges defined in compliance with ASCE/SEI 41 [20]. Nonlinear time-history analyses were applied while gradually increasing the earthquake intensity (_IM_). A set of 20 recorded and artificial ground motions per _IM_ were matched to the Korean design response spectra [21].