Ductility of RC Columns due to Strong Near Source Earthquakes

Near source earthquakes can produce strong vertical ground motions with large amplitude and high frequency content. In this paper the axial ductility behavior of RC columns due to near source earthquakes is investigated. The column is simplified to a SDOF system that only describes vertical vibrations of a structural column. The gravity load effect is represented by a pre-load. An elasto-plastic model accounting for different stiffness and strength in tension and compression is used in the analysis. The ductility demand as well as pseudo acceleration spectra are evaluated. The investigation shows that strong vertical ground motions should be considered in seismic design. From the results of this investigation suggestions for a seismic design in case of near source earthquakes can be derived.