abstract - Iraqi Cultural Attaché

watchpoorUrban and Civil

Nov 15, 2013 (3 years and 10 months ago)

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ABSTRACT


It is rather common today to apply steel fibre reinforced self compacting concrete

(SFRC) ground slabs. The major benefits are that the demanding handling of steel bar

reinforcement is eliminated and that no external vibrators are needed for the

compaction. An obstacle for the application of steel fibre reinforced concrete (SFRC)

is, however, that a method for the design with regard to the after crack stages is

lacking. The work presented in this thesis has thus primarily focused on methods to

ev
aluate the efficiency of steel fibres in this regard.


The effect of fibre properties and soil stiffness on the response of high strength

concrete (HSC) ground slabs to central loading is studied. The methods used include

experimental measurements on a lar
ge number of specimens. Analytical models were

proposed for calculating load
-
deflection relationships for HSC ground slab based on

deriving moment
-
curvature combined with the equations of elastic
-
plastic. Materials

nonlinearity behaviour is included in the

analysis based on different stress
-
strain

relationships for the slab constitutive materials, and from the proposed stress strain

curves from the literature. The behaviour of HSC ground slabs reinforced with fibres

has not been reported in literature; rese
arch has so far been limited on normal strength

concrete. One of the aims of this project is to show how the addition of fibres affects

HSC slab strength, stiffness, collapse pattern and mechanism, and ductility. In the

laboratory, eight slabs were loaded
to failure under central point load in the structural

laboratory. The slabs were tested on ground invented by making a box filled with two

different types of soil, one consisting of loose sand and the other of compact soil. The

slabs were subjected to a gr
adually increasing load, the strains and deflections were

then measured. Beam, cylinder and cube samples were tested to obtain stress
-
strain

and load
-
deflection curves. Test results indicated that both cracking and ultimate

loads are enhanced due to fibre
addition for all tested slabs on loose and compacted

sub
-
grade. Comparison of the predictions of theoretical model with test data indicates

that both cracking and ultimate loads are reasonably close to each other. The complete

load
-
deflection relationship
is in moderate agreement with the test data. The reason

for this is that the test load
-
deflection relationship was quite sensitive to the changes

in fibre content.