Abstract
The objectives of the present paper are to evaluate probabilistically the load level of column over–designed frame structures under a specific reliability level and to present target values for the column over–design factor (COF) by which undesirable story mechanisms can be avoided probabilistically. After the linear relationship between the load level and COF is derived, the likely story mechanisms are analyzed. The basic and optimum COFs probabilistically to avoid story mechanisms are proposed and evaluated for multi–story frames. It is found that the basic and optimum COFs increase with the increase in the number of stories and decrease with the increase in target reliability level of the frame. An evaluation example of a frame with non–uniform column strength over the height is also presented.
