Abstract
The purpose of this paper is to clarify the rigid zone lengths for footing beams. The rigid zone lengths were calculated from the results of finite element analyses of footing beams. The equations to estimate the rigid zone lengths were derived to utilize those rigid zone lengths. The estimated rigid zone lengths were applied to the 3-spans 5-stories and 9-stories reinforced concrete frame, and those frames were analyzed by stiffness method. The results of the analyses were in very good agreement with the results of finite element analyses of those frames.