Article is devoted to calculation method development to obtain response of structure subjected to multi-component seismic load. Brief overview of existing response calculation methods is presented. The model under consideration was calculated on seismic influences in direct dynamic formulation in simulation software ANSYS 14.5 and LIRA 10.2 R3. Maximal and minimal «envelope» spectra were obtained to evaluate maximum and minimum structure responses respectively. Special macro to calculate maximal and minimal «envelope» spectra was developed using Ansys Parametric Design Language. Comparison of results obtained using common methods with results obtained using proposed method is presented.