Civil Engineering Reference
In-Depth Information
Fig. 6.14 Small cover of beam M-0
6.5 Conclusions
An experimental program including shear tests on twenty-two reinforced FRC
beams has been developed to investigate how the quality of the
uence
in shear behavior and the differences on behavior between reinforced beams with
bers can in
fl
bers a with stirrups. From the obtained, the following conclusions can be drawn:
Shear strength and load de
fl
ection response shown an important dependence on
ϕ
the
ber type. Low strength concretes with
6 stirrups shows a very brittle
postcracking behavior while beams with BN
bers were the most ductile. For all
strength levels, beams with BP
bers and stirrups reached the highest loads.
Beams with stirrups show an important deflection increase just after the rst
crack and a greater load reduction after the peak. Beam with stirrups reached
higher de
fl
ection and crack openings, if compared with SFRC.
The parameter f
R3
, as a reference value for calculating shear strength, could be
unsafe or overconservative. In these small beams (in this chapter), the parameter
f
Rm
(average value between f
R1
and f
R3
) may be more appropriate than f
R3
.
Beside f
R3
, also f
R1
, plays a major role in shear behavior and shear strength of
beams. This fact suggests using equivalent energy (f
eq
) to determine the shear
strength of FRC beams in structural codes.
In this program, safety margins obtained as V
test
/V
theo
(the shear test value
divided by the shear theoretical value) were lower than the unit, so unsafe, when
real values of the longitudinal reinforcement ratio
ˁ
l
were used. The small cover
of the main reinforcement may be the reason. Safety margins were low also for
traditional reinforcements, even if stirrups yielded at failure.
Search WWH ::
Custom Search