Authors
Abstract
The phenomenon of dowel action as a shear transfer mechanism across cracks
has long been recognized as an important component of the overall shear resistance
capacity of reinforced concrete beams. The dowel contribution to shear depends
primarily on the tensile resistance of concrete along the splitting plane and the
bending resistance of the longitudinal bars. Fiber Reinforced Ultra High
Performance Concrete (FRUHPC) is an advanced cementitious material consisting
of a dense, high strength matrix containing a large number of evenly embedded
steel fibers. Therefore, FRUHPC can be expected to improve dowel and friction
resistance to shear.
This paper reports the experimental study of the components of shear force
applied to FRUHPC beams, especially the effects of friction shear force and dowel
action. Six FRUHPC beams (120*150*1500)mm dimensions with and without
preformed cracks were made with three volume fractions of fibers: 1% , 1.5% and
2%. The presence of steel fibers enhances the performance of shear transfer
mechanisms by friction or interface shear along the diagonal crack surface. Thus
the contribution of this mechanism to the total shear strength carried by the beam
was around 36.4% for FRUHPC beam with 2% fibers content. In the absence of
friction or interface shear along the diagonal crack surface mechanism (preformed
cracks beams) dowel action was the predominate contributor. However, the
contribution of this mechanism to the total shear strength carried by the beam was
around 45.4% for HPRPC beam with 2% fibers content. Also, an expression for
evaluating the dowel force is presented in this research. The coefficient of multiple
determination (R2) was (0.835).
Keywords
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