SHEAR DESIGN OF HAUNCHED CONCRETE BOX GIRDERS OF THE CONFEDERATION BRIDGE

The paper presents theoretical evidence that for haunched concrete gir ders the conventional approach of including the contribution of the sl oped compression force to the shear resistance defined by the term (M/ d(v)) tan beta, where M is moment, d(v) is internal moment arm, and be ta is the slope, is unsafe. This is so because the compression force i n a concrete girder with shear cracks is smaller than M/d(v). The vari able angle truss model, which is the basis of the general method for s hear design in CSA-23.3-M84, is used for the derivation of the relevan t equations. This approach was used to check the shear design of the C onfederation Bridge.