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Effect
of steel fibres and longitudinal reinforcement in
effective moment of inertia of reinforced high strength
fibrous concrete beams
J.
Premalatha and R. Sundara Rajan
Steel
fibre reinforced concrete is increasingly used as
a construction material. Studies show that steel fibres
can be used to increase the flexural rigidity (EI)
of the concrete beams. In this experimental work eighteen
beams with 80 MPa compressive strength and having
tension and compression reinforcement and deformed
steel fibres were tested under two point loading.
The flexural rigidity of cracked rectangular reinforced
concrete beams with steel fibres was evaluated experimentally.
Considering the steel fibres influence compression
and tension reinforcement (longitudinal reinforcement),
a change in ACI Building code method for estimating
the effective moment of inertia of the section for
the Reinforced High Strength Fibrous Concrete (RHSFC)
beams is proposed.1 The effective moment of inertia
estimated using the changed method was compared with
the experimental results. Good agreement existed for
the predicted deflections with the experimental deflections
of all the eighteen beams with different quantities
of steel fibres and different longitudinal reinforcement
ratio.
Structural
behaviour of hybrid fibre reinforced concrete beams
G. Mohankumar
and L. Bangaru Chandran
Combination
of high modulus metallic fibres and low modulus synthetic
fibres incorporated in conventional reinforced concrete
(hybrid fibre reinforced concrete) HFRC exhibit high
performance. An attempt has been made to study the
flexural response both by preliminary studies as well
as static loading on beams of HFRC. HFRC beams having
1 % fibre fraction with five different combinations
of steel and polyolefin fibres were cast and tested.
The improvement in the material properties and structural
performance of beams was significant. Based on the
experimental results, the optimum fibre ratio of steel
and polyolefin fibres is reported.
Natural
rubber latex modified fibre concrete - Initial studies
for structural performanceR.Sreekala,
K.Muthumani, K.Sathish Kumar and N.Gopalakrishnan
Safety
and performance requirements of building structures
have necessitated the development of High Performance
Concretes in the recent years. Polymer modified fibre
concrete assumes an important place in this regard.
Ductility of reinforced concrete elements can be taken
advantage of for design of structures against seismic
load. Polymer modified fibre concretes are ideal for
such applications with their inherent structural characteristics.
Initially a study on the stress-strain behaviour has
been carried out on different types of concretes namely
plain high strength concrete, fibre concrete and the
natural rubber latex modified fibre concrete with
varying percentages of latex by testing under uni-axial
compression. Selecting Natural Rubber Latex Modified
Fibre Concrete (NRLMC) an experimental investigation
has been undertaken to understand the flexural behaviour
of natural rubber latex modified fibre concrete beams.
Analytical modelling of the beams was carried out
in user friendly finite element software to predict
the monotonic behaviour of the beams.
Studies
on fibre reinforced prepacked concrete
Lalu Mangal,
Arun Edwin and S. Suresh
Prepacked
concrete is prepared by first placing the coarse aggregate
into the formwork and then injecting cement-sand grout,
with a grout fluidiser added, to fill the voids between
the aggregate particles, either by gravity penetration
or by injection under pressure. The present study
investigates the essential properties of fibre reinforced
prepacked concrete such as compressive strength, split
tensile strength, flexural strength, modulus of elasticity
and Poisson's ratio, to establish the suitability
for its use as a construction material. Based on the
study, it is concluded that prepacked fibre reinforced
concrete has definite advantage over ordinary concrete
for use in normal construction.
Durability
studies on glass fibre SCC
P. Srinivasa
Rao, Seshadri Sekhar. T and P. Sravana
Experiments
were conducted to study the effect of glass fibres
on the durability parameters of self compacting concrete
(SCC). Permeability, loss in compressive strength
and weights were evaluated. Durability of M30, M40
, M50 and M60 grades of concrete immersed in H2SO4,
HCl and Na2 SO4 solutions for 28, 56, 90 and 180 days
were also evaluated. The test methods for finding
out the rheology of fresh SCC included aeration measure.
Several mixtures were used for Slump Flow, V-Funnel
and L-box for proportioning of ingredients and admixtures
for both with and without glass fibre concretes. It
was noted that adding glass fibres improved durability
of self-compacting concrete. The weight and compressive
strength losses in cube specimens reduced with age
and in general the durability indicators of glass
fibre self-compacting concrete mixes were more than
those of the self-compacting concrete mixes.
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