Large container cranes are normally designed to resist severe wind. Safety devices such as stowage pins and tie-downs prevent them from being slided or overturned. However, even when the wind speed a little bit exceeds design level, they sometimes undergo total collapse. This may be due to the fact that the total force exerted on the structure increases in proportional to the square of wind speed. But, another important fact is uncovered in this study. Tensions occurring at tiedowns increase much faster than that of main bodies. Therefore, very small amount of excessive wind speed may cause fatal increases of tension at tie-downs. The increasing rate of wind speed and the member force of safety devices were compared in numerical example and it was also proved theoretically. One of the most probable causes of collapsed container cranes at Shingamman port, Busan, was revealed by this phenomenon. In conclusion, it is recommended that safety factor for mooring devices should be larger than that for structural members.
Large container cranes have played an important role in dealing with freights at harbor. Nevertheless, the safety of container crane has not been much noticed. This is only reminded when they undergoes a sudden collapse due to earthquake or high wind. In this situation, some significant findings regarding the safety devices are introduced in this study. A prototype container crane was modeled and analyzed by using commercial FEM code, SAP2000. The member forces occurring at safety devices were found with various wind speeds exceeding design level. Then the trends of tension and shear forces at safety devices are analyzed and some important phenomena were found. Only static analysis of a crane structure is done since the dynamic effect is negligible when it is exposed such strong wind as typhoon (Hiroshi Seki, 1995).
