A Novel Reinforcement Pattern for Exterior Reinforced Concrete Beam-Column Joint

Abstract

Abstract Current design philosophy permits moment-resisting frames subjected to cyclic loading to be induced into the inelastic range where the forces that develop in parts of the structure will exceed their design values. In this phase of inelastic range the beam-column joints are obliged to resist high horizontal and vertical shear stresses coming from the adjacent beams and columns. This occurs during a large number of inelastic cycles and while the joints need to dissipate large energy values. However, in spite of systematic research that has been carried out investigating the behavior of reinforced concrete beam-column connections in the past 20 years in the US, New Zealand, Japan, we have not succeeded in improving satisfactorily this behavior, the specific features of which are extreme decrease of strength, stiffness and energy dissipation capacity, all of which may lead to collapse of the whole building. Attempts at improving beam-column joint performance resulted in nonconventional methods of reinforcing, such as the use of fiber concrete. Paulay, Park and Phillips first introduced the concept of using inclined main reinforcement to prevent brittle failure in short reinforced concrete coupling beams. Following the work of Paulay, Park and Phillips, Minami and Wakabayashi and Tegos and Penelis applied the idea in short columns. The results showed that the columns with inclined reinforcing bars performed considerably better than those with conventional reinforcement. Beam-column joints have many similarities in geometry, state of stress and mechanical behavior with short columns and coupling beams. For these reasons, the efficiency of a novel nonconventional reinforcing pattern by the use of crossed inclined bars in column is examined as a way of improving the seismic performance of type 2 exterior beam-column joints.