Journal of the South African Institution of Civil Engineering
On-line version ISSN 2309-8775
This paper presents a study which investigates the feasibility of a concept to reduce the size of shear wall foundations for earthquake forces in regions of moderate seismicity. The approach is to allow rocking of the shear wall foundation and to include the contribution of a shear wall and reinforced concrete frame to assist as a lateral force-resisting system. A simplified multi degree-of-freedom model with non-linear material properties was used to investigate this lateral-force-resisting system subjected to base accelerations from recorded ground motions. An example building was studied with the shear wall foundation designed to resist 0%, 20%, 40%, 60%, 80% and 100% of the design overturning moment from the seismic event. Non-linear time-history analyses were performed with input from seven scaled ground-motion records. It is shown that the concept warrants more detailed studies and that a significantly reduced shear wall foundation size is possible without failure of the lateral force-resisting system.
Keywords : rocking foundations; moderate seismicity; structural frame; time-history.