UCLA

Reinforced concrete structural walls are a widely used structural system in modern construction in regions where strong ground shaking is likely to occur. For performance-based design of structural walls, including coupled wall systems, it is necessary to model cyclic responses with strength and stiffness deterioration of the prototype system over a wide range of shaking intensities. Current models typically incorporate strength loss using ad-hoc approaches that manipulate material relations to produce strength loss that are difficult to calibrate for the broad range of expected shaking intensities. To address this issue, a model is proposed that captures strength and stiffness degradation compatible with backbone curves that are currently available in the literature. The model is tested in case studies under static and dynamic loading to demonstrate its reliability and effectiveness. The model is refined further to be used for coupled wall systems where the fluctuation of shear and axial load in the coupled piers makes it difficult to pre-determine the deformation parameters of the backbone curves for the piers.In a separate but related study, a database of reinforced concrete wall tests is assembled to develop a new model that estimates the plastic hinge length of flexure controlled structural walls and validate the model against test results. Plastic hinge lengths have been widely used and it is well known that deformation parameters of backbone curves (Structural walls or any other element) depend on element size (Plastic hinge length). The goal of this study is to calibrate backbone curve deformation parameters for a range of wall element sizes and then use the calibrated plastic hinge lengths in the subsequent case studies that incorporate strength loss.