INELASTIC BEHAVIOUR OF THREE-DIMENSIONAL STRUCTURES UNDER CONCURRENT SEISMIC EXCITATIONS

SUMMARY The paper discusses the earthquakes' phenomenon of generating three concurrent orthogonal excitations. The study considered only the two horizontal earthquake radial and tangential components. The SRSS and λ-percent combination methods were investigated for their reliability in the evaluation of the maximum structural response. The results of an extensive elastic and inelastic numerical timehistory study using three-dimensional structures were discussed. These results confirmed that the SRSS and the 30-percent combination methods are inappropriate. The behaviour of the studied inelastic structures was not much different from the elastic structures. The study suggests a 45-percent response combination rule to be used in the elastic and inelastic analyses of structures.