Abstract:
Composite beams are structural members composed of two or more dissimilar materials
joined together to act as a unit. This thesis work studies the behavior and use of structural
steel and reinforced concrete combination as a composite material subjected to fatigue
loading. Fatigue loading is a non-static or cyclic loading. It is a process of a cycle-by-cycle
accumulation of damage in a material undergoing fluctuating stresses and strains. A
significant feature of fatigue is that the load is not large enough to cause immediate failure.
Experimental results are used for validation analysis using ANSYS nonlinear finite element
analysis (FEA) software and further parametric studies on the span to depth ratio, the
configuration of shear studs, and the ratio of reinforcement bars is performed to investigate
the behavioral response of composite beams under fatigue loading.
FEA results showed span to depth ratio of composite beams has significant effect on fatigue
strength of the composite beam whereas shear stud configuration and transverse
reinforcement have negligible effect. To be specific, increasing span to depth ratio of
composite beams under fatigue loading by 41.71% reduced the fatigue strength of the beam
by 83.06% where as a single shear stud arrangement in comparison with a double shear
stud arrangement reduced the fatigue strength of composite beam by 1.75% and an increase
in transverse reinforcement bar ratio by 45.01% increased the fatigue strength by 0.684%.
Increasing span to depth ratio of composite beams under fatigue loading by 41.71% reduced
the shear stress of the beam by 97.93%. Stiffness degradation which causes major fatigue
cracks initiation and propagation is observed to be as a critical concern in the configuration
of shear studs.
