From The 2011 off the Pacific coast of Tohoku Earthquake damage of RC concrete building with steel roof, a new damage has surfaced. Therefore, we were subjected to elastic-plastic response analysis of this building. Then, a new seismic retrofitting method have been proposed. As a result, when the sectional area of the roof brace is increased, the reinforcing effect is not changed even just the outer peripheral. At that time, the cross-sectional area is required about twice. In order to reduce damage to the roof joint, knee brace reinforcement is effective. This reinforcing method can reduce or omit the anchor bolts.
