Effect of reinforcement mergence on the overstrength characteristics of RC frames

Several reinforced concrete frame structures with different stories were designed according to the current Chinese seismic code, in which several schemes of reinforcement mergence were taken into account. The overstrength factor of each structure was calculated by static elastoplastic method. Analysis on the relation of the overstrength factor to the number of stories and the mergence factor show that the overstrength factor decreases with the number of stories increasing but increases with the mergence factor enlarging. The effect of mergence on overstrength is more obvious in low structures than that in high structures. The current Chinese seismic code needs to be revised to consider every factor influencing the overstrength of structures.