Strength and behaviour of deep beams - Reinforced Concrete Deep Beams - page 29

Figure 2.6b Typical stress-strain curves obtained from tests on concrete cylinders under various
states of axisymmetric stress.
Figure 2.7 Typical failure mode of RC beams in flexure.
2.3.2 Shear capacity
As discussed in Section 2.2, shear capacity of an RC beam is defined as the
maximum shear force that can be sustained by a critical-section. When
deemed necessary, shear reinforcement is provided in order to carry that
portion of the shear force that cannot be sustained by concrete alone. The
amount of reinforcement required for this purpose is assessed by using one
of a number of available methods invariably developed on the basis of the
truss analogy concept (Ritter, 1899: Morsch, 1909) which stipulates that an
RC beam with shear reinforcement may be considered to behave as a truss
once inclined cracking occurs.
A prerequisite for the application of the concept of “shear capacity of
critical sections” in design appears to be (by implication) the widely accepted