This paper deals with vibration displacement prediction formulae based on energy balance for boiler structures. The boiler structure is a coupled structure, which consists of the boiler, its support structure and seismic ties installed between the boiler and the support structure. Vibration displacement prediction formulae based on energy balance originally developed by Akiyama et al. were for non-coupled structures like multi-story buildings with elasto-plastic dampers. The formula could predict the vibration displacements using energy spectra as earthquake inputs. However, the formulae could not be applied to the coupled structures like the boiler structures. Considering 1st natural mode of the coupled structure enabled authors to formulate the prediction formulae for the boiler structures. The formulae developed by authors were verified with time history analysis results using a lumped mass vibration model of the boiler structure.
