Analysis of strength reduction factor of RC frames

The strength reduction factor is the key factor in determining design seismic force. The ductility reduction factor, overstrength factor and strength reduction factor of RC frames designed according to current Chinese seismic code are calculated. A method for calculating the ductility reduction factor are proposed based on capacity spectrum method. Nine RC frames with different heights and design seismic zones are calculated using pushover methods. It is concluded that the structures with higher design seismic level have lower reserve strength when they have the same heights, while the reserve strength will decreased with the increasing heights in the same design seismic level. The current Chinese seismic code are evaluated and some advices are proposed for its future modification.