Design of Wall Structures for In-Plane and Out-of-Plane Forces: An Exploratory Evaluation

The seismic behavior and design of industrial structures and high rise buildings is typically governed by the performance of the corresponding reinforced concrete (RC) or steel-plate composite (SC) shear walls. During a realistic earthquake event, these walls may be subjected to combinations of in-plane and out-of-plane shear forces or moments. However, current design codes and standards do not consider the interaction of in-plane and out-of-plane forces on the design and seismic performance of these RC or SC walls. This paper discusses the findings from a research project focused on the interaction of in-plane and out-of-plane forces on the design of structural walls. Experimental investigations were conducted first to evaluate the influence of out-of-plane shear forces (and moments) on the cyclic in-plane shear behavior of structural walls. Detailed 3D finite element models were developed and benchmarked using the experimental results to gain additional insight into behavior. The benchmarked models were used to conduct parametric studies, add results to the database, and gain additional insights into behavior and design. The paper focuses on the development and validation of an analytical approach and numerical tool that was used to conduct the fundamental axial force-axial strain-bending moment-curvature response analysis of the wall cross-section subjected to combined axial force, in-plane and out-of-plane moments. The numerical tool can be used to track the development and evolution of strains and stresses in all steel and concrete components of the walls cross-section. The model was verified using results from the experimental database for SC Walls subjected to combined in-plane and out-of-plane forces. The verified model will be used to conduct analytical parametric studies, and gain additional insight into the interaction of in-plane and out-of-plane forces, and their influence on the design of structural walls. Finally, the model will be used to formulate design recommendations for wall structures subject to combined in-plane and out-of-plane force demands. The recommendations will enable engineers and designers to consider interaction effects directly.