Seismic analysis of 30/5 ton overhead crane for 30MWTh Korea Multipurpose Research Reactor (KMRR)

The KMRR 4-wheel crane which has a span of 30.6m long shall be designed to maintain its structural integrity during and after seismic shocks. Horizontal and vertical FRS for OBE and SSE conditions at the crane support are used as seismic inputs; horizontal ZPA of SSE and OBE are 0.73g and 0.5g, respectively. The material dampings used in the analysis are 4% for OBE and 7% for SSE. The crane consists of girder, saddle, main and auxiliary trolley, and accessaries. They are modeled as beam elements and lumped masses for the following 4 cases; trolley at center of the crane with and without the rated load, trolley at end with and without the rated load. The static analysis as well as the liner dynamic analysis including frequency and response spectrum analysis are performed for the seismic qualification of the crane using the Finite Element Method. For the simplicity of the analysis, the decoupling criteria are considered for the crane rope and the crane supporting beams. The main sections of the crane are stiffened until the calculated stresses satisfy the allowable limits. The seismic resultant loads are used to design the seismic restraints of the saddle and the trolley to protect the crane from the seismic uplifting loads. The study results have shown that the seismic design of the KMRR crane is governed by the OBE condition, not by the SSE condition. This paper briefly describes the analysis procedure used in the seismic design of the KMRR crane, and summarizes the analysis results. (author)