ULTIMATE SHEAR FORCE OF STRUCTURAL CONCRETE MEMBERS WITHOUT TRANSVERSE REINFORCEMENT DERIVED FROM A MECHANICAL MODEL

For slender members without transverse reinforcement, like reinforced concrete-prestressed concrete slabs, a mechanical model is presented that explains the structural behavior from cracking until failure. The shear force is mainly transferred in the web. A simple distribution for the friction stresses along the crack is assumed and the resulting state of stress in the web of the member is clearly described. From a condition for the crack width in the web, an explicit equation for the ulltimate shear force is derived, which consistently describes the influence of axial forces and prestress. This model gives a clear explanation for the influence of the depth of the member on the ultimate shear force as well as that of the reinforcement ratio. Finaly, dimensioning diagrams are presented for the common case of reinforced concrete members like slabs.