Abstract:
A reinforced concrete structure may be subjected to four basic types of actions: bending, axial
load, shear and torsion. All of these actions can, for the analyzed and designed by a single
unified theory based on the three fundamental principles of mechanics of materials: namely, the
stress equilibrium condition, the strain compatibility condition, and the constitutive laws of
concrete and steel. Because the compatibility condition is taken into account, this theory can be
used to reliably predict the strength of a structure, as well as its load–deformation behavior.
Concrete and steel bar are idealized as uniform and continuity materials, smeared (average)
stress-strain relations of concrete and steel bars should be used. The smeared stress-strain
relationships of concrete for precast concrete beam have been proposed in soften compression
curve and stiffening tensile curve. This study proposes a smeared stress-strain relationship of
steel bars embedded in concrete. Also a Belarbi’s model is proposed, the analytical approaches
are stated. Using the smeared stress-strain relationship of concrete and steel bars for model of
precast beam.
In this study, the pre-cast concrete beam has been modelled and analyzed when subjected to two
point loads at one third spans from each support, using Finite Element Analysis tool, popularly
called ABAQUS software. The modelled and analyzed precast beam cross-section having size
120mm×80mm with 2 numbers of 12 mm diameter bars as bottom reinforcement,12mm diameter
bars as top reinforcement and 6 mm diameter at 150 mm c/c as shear reinforcement. The
behaviour of the analyzed precast beam has been observed in terms of the flexural cracking,
crack pattern, failure load, bucking failure of the stirrups, and maximum deflection. Based on
the analysis carried out on the pre-cast beams using ABAQUS Software, it is found that results
are more sensitive to mesh size, compressive strength, dilation angle, viscosity parameter, and
static load. The model is validated using different experiment results for pre-cast beam elements
presented in the literature. Comparison is made between the experimental results and finite
element analyses with respect to initial crack formation and the ultimate load capacity of precast beams. The results indicate a good agreement with load vs. deflection curve and observed
crack patterns.
