Three‐dimensional dynamic analysis for multi‐component earthquake spectra

Abstract At the present time, there is a need for a rational approach for the analysis and design of three‐dimensional structures subjected to multi‐component earthquake motions. In this paper, a general design criterion for multi‐component earthquake input is proposed. A new method for three‐dimensional dynamic analysis is presented which estimates maximum displacements, forces or stresses for specified points within a structure. For each maximum value calculated, the corresponding critical angle of earthquake input is evaluated. The method is readily incorporated into existing computer programs for earthquake analysis, allowing one computer run to produce mean maximum response values for all possible angles of earthquake input. Combined axial and bending stresses are calculated at the modal level. It is shown that combining modal stresses yields lower estimates than if stresses are evaluated from maximum axial forces and moments. In addition, the method can be used without modifications to perform design checks for arbitrary blast or seawave spectra.