| Abstract: | In this paper seismically induced overturning effects in stiffened building frames are studied by examining the response of two structures: a 20-storey ‘core wall’ reinforced concrete frame and a 10-storey steel braced frame. The excitations utilized in the study are the 1971 Pacoima Dam S16E Record and the 1940 El Centro N-S Record magnified by a factor of two. Non-linear effects of the following types are considered: plastic hinging of beams and columns, yielding and/or buckling of bracing members and transient uplift of portions of the structures from the foundation. In particular, comparisions are made between response with unlimited base overturning capacity assumed and response with dead-weight overturning resistance only. Providing dead-weight overturning resistance only is shown to significantly reduce seismic load levels, with relatively little or no loss in drift control. Ductility demand in these stiffened frames is shown to be limited, when transient uplift is allowed, to the link beams connecting stiffened and unstiffened portions of the structures. |
