Seismic Capacity Test of Overhead Crane Under Horizontal and Vertical Excitation -Element Model Test Results on Nonlinear Response Behavior-

Abstract

In seismic safety assessments of nuclear power plants, it is important to determine the seismic capacity in terms of the structural strength and operative function of equipment. Since the revised regulatory guidelines for reviewing the seismic design of nuclear power reactor facilities in Japan requires dynamic analysis for vertical excitation, it is important to confirm the seismic capacity of equipment under vertical excitation. An overhead crane used in a boiling-water nuclear reactor building is a typical piece of equipment with low rigidity that is affected by vertical response amplification. A strong earthquake might cause nonlinear behavior such as sliding, or jumping and the resulting landing of the overhead crane, which may result in its derailing from the track. Accordingly, the Japan Nuclear Energy Safety Organization initiated a seismic capacity test program in Fiscal 2006. The program included two test series for investigating nonlinear behavior, structural strength, and validity of the structural retrofit against vertical excitation. The first test series was a preliminary element model test for investigating basic features, and focused on certain issues concerning nonlinear behavior under vertical excitation. The second test series was a shake table test of a 1/2.5-scale model with the same structure as an actual crane. This paper reports the test results obtained from the former element model test. We clarified the nonlinear behavior of an overhead crane under vertical excitation.