9416466 Stanton A number of reinforced concrete structures collapsed, either partially or totally, in the Northridge earthquake. Some of the collapses were attributed to the failure of columns which were designed for gravity loads only. Many engineers perform the evaluation in terms of the moment strength of the columns. This is an inappropriate approach because the real issue is rotation capacity and not moment capacity. The research undertaken here will investigate two aspects of the issue. The first is to develop analytical tools with which to predict the story drift that a column can undergo without failure. The approach to be used is to construct interaction diagrams relating axial force to curvature capacity, rather than the conventional axial load to moment capacity. Curvature is related to rotation which in turn can be used to predict story drift capacity. The vertical accelerations and the shear strength will be taken into consideration in the analysis. Innovative column details will be developed that will permit larger inelastic rotations before failure. One approach is to detail all columns using the full seismic ties required in the lateral load resisting part of the frame. Other details will be developed that depend on either providing local flexibility at the column ends or on providing localized confinement to prevent bursting and/or shear failure. These column details which will be simple, economical, and easy to inspect and build will be recommended. This is a Northridge Earthquake project. ***
