Nonlinear fiber modeling of steel-concrete partially composite beams with channel shear connectors

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2017
Öztürk, Alper
The purpose of this study is to develop a nonlinear fiber-based finite element model of steel-concrete composite beams. The model was developed in OpenSees utilizing the available finite element formulations and the readily available uniaxial material constitutive relations. The model employed beam elements for the steel beam and the concrete slab, while zero-length connector elements were used for the steel-concrete interface. The channel shear connector response used in numerical models was based on the previously obtained experimental response from pushout tests. Accuracy of the numerical models in predicting the response of composite beams with varying degree of composite action was verified with the results of the previously conducted composite beam tests. The response of composite beams was studied in terms of moment capacity, stiffness, cross-sectional strains, and interface slip. The slip behavior through the beam length was also verified with the analytical solutions in the literature. Progression of damage due to cracking and crushing of concrete slab as well as tension and compression yielding of steel beam was studied in relation to the degree of composite action present. The numerically predicted response agreed well with the experimental results over the entire range of load-deflection curves for both the fully composite and partially composite beams. The numerical models were also able to accurately predict the interface slip between the steel beam and the concrete slab when compared to the experimentally determined slip values, as well as the closed-form slip predictions. Concrete cracking in slab was observed to start at very early stages of loading and progress very quickly irrespective of the degree of composite action. Concrete cracking was followed by the initiation of yielding at the bottom part of the steel beam. Yielding in the lower parts of the steel beam was observed to be more extensive in models with full composite action compared to the partially composite beams. The point that the initial portion of the load-deflection curve of composite beams deviates from linear response corresponded to the yielding of the entire bottom flange of steel beam.

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Citation Formats
A. Öztürk, “Nonlinear fiber modeling of steel-concrete partially composite beams with channel shear connectors,” M.S. - Master of Science, Middle East Technical University, 2017.