Truss model approaches and related theories for the design of reinforced concrete members to resist shear are presented. Realistic models for the design of deep beams, corbels, and other nonstandar...

Recent Approaches to Shear Design of Structural Concrete

Predicting the shear strength of reinforced concrete beams using artificial neural networks

It is not correct to state that the collapse of the Wilkins Air Force Base depot building occurred without warning. The structure was known to be extensively cracked in shear well before the collapse, and it is the discusser’s understanding that some beams in the building were already being braced with shoring consisting of various wooden poles. The observer was in fact looking for additional trouble at the time of the collapse, although it must be argued that the fact that the failure occurred while he was present was coincidence. The record of cracking for the particular design at Wilkins was so bad that a revised design had already been prepared and was used in some similar buildings. The January 1957 issue of the ACI Journal had several articles dealing with the failure and with the repairs to other structures of the same group that had not failed but that were showing significant shear cracking.

The earliest applications of the finite element method to concrete structures included crack modeling [1–3]. Such modeling, then and now, can be completely characterized by two essential elements. These are the manner of inclusion of a crack in the finite element mesh, and the criterion for crack instability and direction of growth.

Numerical modeling of discrete crack propagation in reinforced and plain concrete

This paper describes the development of the 2004 Canadian Standards Association (CSA) A23.3 shear design provisions for reinforced and prestressed concrete structures. These methods are similar to ...

Development of the 2004 Canadian Standards Association (CSA) A23.3 shear provisions for reinforced concrete

The nature of shear resistance of reinforced concrete beams is examined, and it is shown that shear may be resisted in two different ways, namely by beam and arch actions. At the diagonal cracking load of the shear span, beam action breaks down. Unless the beam contains pre stressed reinforcement arch action cannot develop to an appreciable extent prior to the diagonal cracking. It is shown that the strength of beam action depends largely on the mechanism of shear transfer across the crack by interlocking of the aggregate particles, and to a lesser extent by dowel action of the reinforcement. Direct tests on aggregate interlock action show that this shear transfer increases with concrete strength, and a reduction in crack width. From tests the dowel capacity of bottom bars is found to be considerably greater than that of top bars. Beam tests illustrate the contradictions of these different mechanisms.

R. C. Fenwick

Papers

Mechanism of Shear resistance of Concrete Beams