Post-buckling behavior during earthquakes and seismic margin of FBR main vessels

Shaking-table tests of cylindrical shells were performed in order to examine the buckling and post-buckling characteristics of FBR main vessels under seismic shear loads. Static buckling tests were also performed, and it is confirmed that there is no significant difference between the static and dynamic load-displacement relations. Based on the test results, hysteresis rules of restoring force were formulated for both elastic and plastic shear-buckling. Non-linear dynamic-response analyses of the single-degree-of-freedom (SDOF) system were then carried out by using the hysteresis rules. The analyses were able to simulate the dynamic test results, especially energy-absorption capacity due to hysteresis behavior. Finally, the non-linear SDOF analysis was applied to the FBR main-vessel cylinder. It is pointed out that the hysteresis behavior could absorb a considerable amount of energy input from seismic motion, which would contribute to the seismic margin of FBR main vessels.