# Seismic Response of Container Crane under Near-Field and Far-Field Ground Motions
## 2 Shaking Table Test of Container Crane
### A 1/20 Scale Container Crane  
A container crane located at Gwangyang port was employed to design a 1/20 scale container crane. The scale factor of 1/20 was selected based on the size of the shake table in the Seismic Research and Test Center. The basic properties of the prototype crane include a total height of 78 m from the ground to the top of the crane, a trolley boom girder length of 136 m, a portal beam height of 17.5 m, a crane rail span of 30.5 m, and a total mass of approximately 1175 tons. The total mass of the prototype crane comprises the self-mass of the crane of 885 tons and the mass of other non-structural components of 290 tons. The other non-structural components include the machinery house, drive trucks, stairs, stowed pins, snag device, and boom hoist rope. The scale factors (see Table 1) were calculated based on the similitude law to design the 1/20 scale crane. Three independent quantities: geometric length, acceleration, and elastic modulus, were used as a basis to establish the other factors. During seismic excitations, the legs of the container crane will experience large strains due to their bending deformation caused by the inertia loads of the crane's frames and other components. Therefore, the container crane's legs are the most critical and vulnerable components of the crane structure, and their stiffness should be given priority to satisfy when designing the 1/20 scale crane. In this study, each part of the 1/20 scale crane's cross-sections could not be designed according to the scale factor for the geometric length due to the limitation of size. Therefore, they were designed using the scale factor for the moment of inertia to meet the equivalent stiffness of the 1/20 scale crane. The scale factors for converting the quantities from the prototype crane to the scale crane were determined by Equation (1):  
\[S_{t}=\frac{L}{l};\ S_{E}=\frac{E}{e};\ S_{a}=\frac{A}{a};\ S_{m}=\frac{M}{m}; \ S_{t}=\frac{T}{t};\ S_{I}=\frac{I}{i} \tag{1}\]  
where \(S_{t}\), \(S_{E}\), \(S_{a}\), \(S_{m}\), \(S_{t}\), and \(S_{I}\) are the scale factors of geometric dimension, elastic, acceleration, mass, time, and moment of inertia, respectively. It should be noted that the uppercases in Equation (1) describe the quantities of the prototype crane, while lowercases indicate the quantities of the scale crane.  
The 1/20 scale crane is shown in Figure 1. The total converted mass of the scale crane was 2939 kg. After downscaling the prototype crane's cross-section, the self-frame mass of the scale crane was only 235.5 kg, thus requiring the introduction of additional mass to the scale crane [26]. Consequently, an additional mass of 2703.5 kg was attached to the scale crane in two ways: by using steels bars, which were attached to the trolley-boom girders and apex beam by weldings and bolts; and lead ingots, which were attached to the upper landside and seaside legs, the lower landside and seaside legs, portal beams, and sill beams by using steel ties to avoid influencing their stiffness. The boundary condition for the scale container crane was modeled as pin support, which allowed the crane leg to rotate about the y-axis (perpendicular to the trolley-boom direction) but restrained movement in both the horizontal and vertical directions.