Shear design of haunched concrete box girders of the Confederation Bridge

Abstract

The paper presents theoretical evidence that for haunched concrete girders the conventional approach of including the contribution of the sloped compression force to the shear resistance defined by the term (M/d V ) tan β, where M is moment, d V is internal moment arm, and β is the slope, is unsafe. This is so because the compression force in a concrete girder with shear cracks is smaller than M/d V . The variable angle truss model, which is the basis of the general method for shear design in CSA-23.3-M84, is used for the derivation of the relevant equations. This approach was used to check the shear design of the Confederation Bridge.