Evaluation of plastic hinge length estimations and strain limits of reinforced concrete shear walls

Lateral displacement of a reinforced concrete shear wall is basically comprised of two primary parts which are shear and flexure. Flexural part constitutes the larger portion of total displacements that includes contributions from both elastic and plastic branch of the response whereas shear part is mostly overlooked for slender walls for which the shear-flexure interaction is not expected to have a profound influence in overall behaviour. To assess the global scale deformation capacity of a reinforced concrete shear wall, there are several simulation/modelling techniques proposed in the literature. Plastic hinge analysis (PHA), is one of the simplest and widely utilized numerical methods to predict displacement capacity or to determine local damage state for a specific drift demand imposed by ground motions. The efficiency of the assessment via plastic hinge analysis method immensely depends on adopting the appropriate estimations of the plastic hinge length and the strain limits. Typical building codes and several researchers recommend taking the plastic hinge length at the wall base as the half of the wall length. However, for most of the cases, this simplicity may yield unreliable results since the plastic hinge length is not only impacted by wall length but also influenced by several more parameters which will be discussed further. Another concern is given to proposed strain limits of which applicability to shear walls is a huge question mark on the ground that most of them are calibrated for pure axial compression or tension effects. To address these issues, a dataset of 49 shear wall test is assembled and studied for the validation of plastic hinge analysis method. Subsequent to plastic hinge analysis method, a moment-curvature analysis was performed for all specimens. The major outcomes of the study are as follows; Adopting the right failure criterion based on anticipated failure mode as means of predicting the displacement capacity is of crucial. A new expression is proposed to predict the failure mode of shear wall which utilizes section analysis results. The performance evaluation procedure based on compression side strain limits for shear walls is related to large uncertainties and compressive strain limits are not as dependable as those for reinforcing bars. The use of the equivalent plastic hinge length to half the wall length may jeopardize the reliability of the PHA method. The estimation of Eurocode 8, in general, well agrees with the experimental results.