Title: Ultimate shear force of structural concrete members Without Transverse Reinforcement Derived From a Mechanical Model (SP-885)

Author(s): Karl-Heinz Reineck

Publication: Structural Journal

Volume: 88

Issue: 5

Appears on pages(s): 592-602

Keywords: aggregate interlock; building codes; compatibility methods; concrete slabs; cracking (fracturing); dowels; failure mechanisms; prestressed concrete; reinforced concrete; shear properties; shear strength; tensile stress; transverse shear; Structural Resea

DOI: 10.14359/2784

Date: 9/1/1991

Abstract:
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, i.e., in the tension zone of the member, by friction along the crack surfaces (aggregate interlock), and by the dowel action of the longitudinal reinforcement. 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, which can be illustrated by a simple truss model with tensile struts in the concrete. From a condition for the crack width in the web, an explicit equation for the ultimate 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 (size effect) as well as that of the reinforcement ratio. Finally, dimensioning diagrams are presented for the common case of reinforced concrete members like slabs.