Design Procedures of Seismic-Isolated Container Crane at Port

Abstract eng:
Most of the container cranes were damaged in Kobe port during the 1995 Hyogoken-Nambu Earthquake. Because the container operation could not be performed, various type of losses were incurred such as economical losses, permanent shift of container ships from Kobe port to other ports, etc. Currently, the seismic design method of a container crane is adopted the ‘seismic coefficient method’(pseudo static method). In case of extremely high intensity input seismic motion such as Level 2 input motion, the dynamic behavior of a container crane is expressed in terms of lift off of the legs from the rails and locking motion. The current design method can not treat the behaviors mentioned above. To evaluate and develop the design method for the Level 2 input motion, 1/30 scale model shake tests, simple mass-spring numerical analyses and 3-D dynamic FEM analyses were conducted. From the model shake test results, a threshold acceleration level of the lift off of the legs from the rails showed good agreement with a pseudo static horizontal acceleration of lift off the legs predicted in the design method. Proposed 3-D FEM model of container crane can simulate the dynamic behavior of a crane model during a shake table test even when the legs lifted off from the rails. The simple mass-spring model is also useful numerical method for the case of smaller acceleration level when the legs lift off. In practical point of view, we proposed simplified dynamic response analysis for base-isolated container crane consideration with model tests, 3D-FEM, 2D-FEM, Frame model and simple mass-spring model.

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