NONLINEAR FINITE ELEMENT MODELING OF REINFORCED CONCRETE STRUCTURAL WALLS

A relatively simple finite element modeling methodology was developed for simulating the cyclic lateral load behavior of reinforced concrete structural walls with varying levels of coupling between nonlinear flexural and shear response components. The behavioral characteristics of the constitutive panel elements incorporated in the model formulation are based on a fixed-crack-angle modeling methodology, which is effectively a smeared-stress-strain-based strut-and-tie approach that does not require ad-hoc model parameters. The constitutive panel model formulation also incorporates simple yet effective behavioral models for the shear-aggregate-interlock effects in concrete and dowel action on reinforcing bars, constituting the shear stress transfer mechanisms across the cracks. The model formulation was implemented into Matlab and model response predictions were compared with experimentally-measured responses of selected wall specimens with varying geometry and reinforcement characteristics; including relatively slender (aspect ratio of 3.0) walls with rectangular and T-shaped cross-sections, squat walls (aspect ratio of 0.5) with shear-controlled responses, and medium-rise walls (aspect ratios of 1.5–2.0) with predominant shear-flexure interaction responses. The proposed finite element modeling approach demonstrates a reasonable level accuracy in predicting the nonlinear hysteretic response of the wall specimens investigated. Accurate predictions are obtained for the experimentally-measured response attributes of the walls; including their lateral strength, stiffness, and ductility, as well as their hysteretic response characteristics. The model also provides accurate estimates of the relative contribution of nonlinear flexural and shear deformations to wall lateral displacements, and local response characteristics (e.g., strain distributions). Based on the response comparisons presented, model capabilities are assessed and possible model improvements are identified. Overall, the modeling approach proposed, despite its relatively simple formulation, is shown to provide reliable predictions of the nonlinear lateral load behavior of reinforced concrete walls with various aspect ratios and response characteristics.