Abstract:
The redistribution of moment has been confirmed in reinforced concrete structure by
experimental investigations. It is also a fact that reinforced concrete structures have
comparatively lower capacity to rotate than steel structures. Yet, this phenomenon is
drawing the attention of the designers. Presently, design codes of most of countries allow
the redistribution up to maximum limit. The addition of steel fibers will enhance the
redistribution of moment forming ductile section.
The study characterized the moment redistribution behavior of a steel fiber reinforced
concrete (SFRC) continuous beam subjected to five point bending test modelled in FEA
using constitutive material model. The compression behavior was obtained using uniaxial
compression strength tests while the tensile behavior was obtained using splitting strength
test analysis performed according to flexural test results. These properties were utilized to
derive a theoretical moment-curvature relation for each SFRC member which supplied the
basis for the characterized moment-rotation behavior and the finite element analyses
(FEA) performed on the continuous beam. The laboratory tests for compressive and
splitting tensile strength of SFRC were conducted for volume of steel fibers, 0%, 0.5%,
0.75% and 1.5%. From the tests results it was observed that the compressive strength
increased by 26.8% for 0.5% SFRC, 30.7% for 0.75% SFRC and reduced by 5.3% for 1.5%
SFRC. The splitting tensile strength increased by 11.2% for 0.5%, 5.8% for 0.75% and
2.5% for 1.5% SFRC. Increment of peak strain was also confirmed. The ductility of the
member was increased 1.59 times, 2.41 times and 3.25 for 0.5%, 0.75% and 1.5% SFRC
member respectively, compared to that of the 0 % SFRC member’s rotation capability.
Section moment capacity was also enhanced by Increasing steel fibers volume.
The development of the moment redistribution was accompanied by the rotation of the
plastic hinges at the critical sections in the beam. The amount of moment redistribution of
SFRC reduced as volume of steel fiber increased. So utilizing permissible moment
redistribution for SFRC as prescribed by design standards needs further study.
