Auxiliary Reinforcement in Concrete Connections

A simple but powerful method for the design of connections in precast concrete is introduced. The method is based on a physical model of behavior, rather than on curve-fitting to empirical data. It is thus suitable for a wide variety of connection problems, as well as for connection geometries not covered by previous tests. When properly used, this approach results in reliable, ductile connections which do not suffer from the various types of distress all too common in precast connections. The concrete is assumed to crack in an unfavorable location, in the region of the connection. The shear-friction hypothesis is then used to determine the amount of reinforcing which must cross the assumed cracks. Shearing stresses along an assumed crack are resisted by friction. The normal force required to mobilize friction is provided by reinforcing steel, placed normal to the assumed crack. Applications to composite beams, corbels, bearing shoes, tension splices, and confinement are discussed, and a practical design example is given.