Seismic Fragility Assessment of Attached Cranes on an Integrated Construction Platform for Nuclear Power Containment

Attached cranes on elevated construction platforms may experience amplified earthquake demands, although their seismic performance during nuclear containment construction is insufficiently characterized. A three-dimensional containment–platform–crane model was used for incremental dynamic analysis with 11 ground-motion records and four adopted deformation thresholds. For the reported 0.5 g case, the crane-tip peak displacement was 1.42 times the platform-top value. The median ground peak accelerations at the D4 deformation threshold were 0.275 g for Crane 2 and 0.399 g for Crane 5, a ratio of 1.45, indicating a substantial configuration-dependent difference under the analyzed excitation direction. A crane-group threshold table supports probability-based screening. For assessment using crane-base acceleration, 18 intensity measures were compared; the peak-based measure achieved r = 0.945 and conditional logarithmic dispersion achieved β = 0.260, compared with r = 0.912 and β = 0.327 for Sa_avg. These results support two complementary screening approaches, subject to the assumed stationary, unloaded crane configuration. Record provenance, connection idealizations, limited sampling, and unidirectional excitation constrain quantitative transfer to other projects. The D4 threshold denotes an adopted deformation-exceedance criterion rather than independently verified physical collapse.