UC San Diego
Modeling the Nonlinear Behavior of Confined Masonry Using Discrete Elements
- Author(s): Lang, Anna Frances
- et al.
Confined masonry is a popular, non-engineered building technique used throughout the world. It is especially prevalent in Latin America and Asia and is a seismically safe alternative to unreinforced masonry and masonry infilled frames. Despite its wide use relatively little research has been conducted on these systems especially on large deformation behavior. When available, experimental studies are usually terminated at 80% post-peak strength. Numerical and analytical efforts either are unable to predict ultimate damage states or they predefine failure modes. Quantification of the ultimate capacity of confined masonry could significantly improve the relevance and applicability of catastrophe models for pre-disaster planning and post-disaster response efforts. Nonetheless, a large research gap exists of how structural features of confined masonry contribute to its seismic performance. Advancements in this area could improve and clarify current design recommendations. In an effort to close the knowledge gap, a detailed numerical model is developed of a traditionally built confined masonry shearwall. A micro modeling approach is taken using the discrete element method, which computes the motion and interactions of a large number of discrete individual bodies. This approach allows for realistic and detailed joint behavior as well as large deformations. The model successfully captured the initial stiffness, peak strength, and stiffness degradation of an experimentally tested confined masonry wall. Validation of this numerical approach was performed against micro material tests, as well as the in-plane pushover testing of an unreinforced masonry shearwall. Accuracy of the model, however, is limited by the availability of enumerated joint behavior in the shear and normal directions. The confined masonry shearwall model was then adapted to perform a parametric numerical investigation of geometric and material aspects on seismic performance. Preliminary results suggest that the relative stiffness of the masonry panel to the reinforced concrete frame is of primary importance to lateral capacity