Direct Displacement-Based Seismic Design of Unanchored Cylindrical Steel Tanks for Excessive Plastic Rotations of the Base Plate During Uplift

Past earthquakes have demonstrated the need for performance-based seismic design methodologies for cylindrical steel tanks. This paper presents a direct displacement-based seismic design procedure for unanchored cylindrical steel tanks. By focusing on the expected displacements, direct displacement-based seismic design provides tank design solutions that achieve rather than be bounded by a given performance level under a specified seismic hazard level. The theoretical framework of direct displacement-based seismic design for unanchored cylindrical steel tanks for excessive base plate plastic rotations during uplift is presented and then an application example of the procedure is performed and appraised using nonlinear time history analyses.