Behavior of RC deep girders that support walls with short end shear spans

Abstract

Two design approaches, conventional and strut-and-tie procedures, are developed for reinforced concrete continuous deep girders which transmit the gravity load from the upper wall to the lower columns. This paper presents the results of tests and analyses conducted on two specimens; the first specimen employs the conventional procedure, while the strut-and-tie procedure is used for the second specimen. The conclusions are as follows: (1) The approach of the strut-and-tie method is valid for this type of continuous deep girder rather than the conventional beam approach. (2) Since the upper load is carried over directly to the supporting column through the stiff concrete strut to the point of yielding of the bottom ties, the shear capacity of continuous deep girders is mainly governed by the yielding forces of the bottom ties. (3) The additional shear resistance derives from continuity with the adjacent beams or walls. Shear and top reinforcements in the continuity region can be designed by using appropriate models for the additional margin of safety in terms of strength and ductility. (4) Simulation through two-dimensional nonlinear analyses using DIANA shows a good correlation with the experimental results.