During an earthquake nonstructural elements fail earlier than structural elements because of its brittle failure. Nonstructural walls are one of these elements which its brittle failure reduced significantly the resistance of the entire structure. In this research a study of several numerical integration methods to model the decay of stiffness when the failure of nonstructural elements occurs will be presented. The Newmark-b Method, the Unbalanced Force Correction Method and the Operator Splitting Method were selected for this research.
The software called MDOF was used to study the numerical integration methods. From the results it was concluded that the Newmark beta method is not accurate for large time integration steps. But the Operator Splitting and Unbalanced Force Correction methods are accurate and stable for large time integration steps.
A RC frame with nonstructural walls representing a typical entrance frame of an apartment was constructed and tested in the laboratory of the Building Research Institute (BRI) to study the interaction between the nonstructural wall and the frame. The experimental results were used to model fragile failure of nonstructural walls using a program called STERA 3D which was modified to implement the numerical integration methods mentioned above.
Also a typical confined masonry wall using Peruvian handmade clay bricks tested in the laboratory of Japan-Peru Center for Earthquake Engineering Research and Disaster Mitigation (CISMID/FIC/UNI) in 2003 was analyzed. Its fragile failure was modeled and its results compared with the experiment.
Finally a recommendation to minimize damage on nonstructural elements was done, and at the same time this recommendation reduces the risk of injure and death of human beings due to the failure of nonstructural elements.