This research presents an empirical study about the behavior of High Strength Concrete
beams under the static cyclic loading. It determines the influence of cyclic loading on the
moment capacity and deflection of HSC beams. A comparison of the mome
nt capacity and
deflection in both kinds of loading (monotonic and cyclic loading) were achieved.
High Strength Concrete mixture was designed, based on the specifications of the American
code ACI 211.4R-93. Thirty six concrete beams were prepared, nine of them were tested
under monotonic loading and the rest of beams were tested under cyclic loading. The
cyclic loading was performed for (5,10,15) cycles, at a range from zero to 65%, 75%, 85%
of the minimum expected monotonic load.
The results showed that the cyclic loading have positive effect on the flexural behavior of
HSC members, whereas the moment capacity increased and the deflection decreased,
especially at a range from zero to 75% of the minimum expected monotonic load, when
the number of cycles was 5,10,15.
Recently, the importance of high Strength concrete has appeared due to its
application in manufacturing most of the concrete structures and members, as well as to its
importance in the implementation of civilian facilities like bridge bases, skyscr
apers and in
implementing the columns and platforms which carry oil installations carried out in the
oceans and seas. The research aims to design concrete mixtures with cylindrical resistors
( 55- 65- 75 Mpa) according to the American code AcI-211-4R-93 by using local and
appropriate additions as well as explaining the method used in designing. Then, studying
the transformation in stress strain curve – deformation
(σ- ζ ) undergoing a simple pressure on the previous samples throughout the
available devices. Then, it was compared to the charts obtained mathematically .Law
behaviour of stress strain and deformation curve was rated, in addition to modulus of
elasticity taken from the chart.
Couple of results and recommendations related to the issue were concluded, those
which were applied in praxis.
This paper is devoted to investigate the effect of high temperatures on the behavior
and compression resistance of rectangular high-resistance concrete samples.
In this study, rectangular samples with dimensions of (15X15X15 cm) have been
made and
after 28 days they have been burned in a special oven, then cooled down in the
air.
The exposition of high-resistance concrete samples which made of local sand and
aggregate and use silica fumeoiiuk to high temperatures has led to a reduction and lose in
the compressive resistance of this samples.
When the temperature was 350 c, the reduction in the compressive resistance was
about 13%, and at the temperature of 450c, the reduction was about 36%, and at the
temperature of 850c, the reduction was about 72%.
Therefore, we have to take this reduction of compressive resistance in the concrete
elements seriously when they exposed to fire, so we can take the right decisions about
rehabilitation or conservation or replacement of this elements.
