Confinement Steel Requirements for Connections in Ductile Frames

Results of tests on a large number of beam‐column subassemblies performed by the writers and others are examined. After reviewing the existing techniques, an index is proposed that can quantify the energy absorption and dissipation characteristics of a reinforced concrete frame. Based on this index, a simple design chart is presented for selection of the required area of confining steel for the joint region of R.C. frames so that ductile behavior can be achieved. The confining steel is a function of the joint shear stress and the ratio of the flexural capacities of the columns to that of the beam at the joint. The numerical examples included demonstrate that for the extreme case, the required area of steel obtained from the design chart is comparable to the current ACI‐ASCE Committee 352 recommendations. However, for many other cases, the design chart permits a relaxation of the area of confining steel required. This results in greater ease and economy of construction.