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Sensitivity of Shear Strength of RC and PC Beams to Shear Friction and Concrete Softening According to the MCFT.

Sensitivity of Shear Strength of RC and PC Beams to
Shear Friction and Concrete Softening According to the
MCFT.
(2359 K)

Duthinh, D.

ACI Structural Journal, [pages unknown], 1997.

### Keywords:

concrete beams; biaxial softening; building technology;
prestressed concrete; reinforced concretes; shear
friction; shear strength

### Abstract:

*
The Modified Compression Field Theory (MCFT) is used to
study the effect of shear friction and biaxial softening
on the computed shear strength of reinforced (RC) or
prestressed concrete (PC) beams. A comparison is
presented of the various relationships that have been
proposed to represent the shear friction behavior of
cracked reinforced concrete. A decrease in shear
friction within the range of experimental data, as found
for example in high strength concrete, can lower the
shear strength of beams with minimum shear reinforcement
by 15% to 25%, according to the MCFT. In addition, a
comparison is presented of different relationships used
to represent the biaxial compression-tension strength of
reinforced concrete for RC and PC beams. Some theories
of biaxial softening of concrete do not predict concrete
crushing even for very high deformations, but rather
show significant shear force gain after stirrup yielding
and crack slipping. For the RC beam example, some
theories predict shear tension failure while others
predict diagonal compression failure. However, the
first peaks of shear load, which occur close to stirrup
yielding and crack slipping are within 10% of one
another for the various theories and within 10% of the
test value for the PC beam.
*