Proceedings of the 8 th U.S. National Conference on Earthquake Engineering April 18-22, 2006, San Francisco, California, USA NONLINEAR WALL MODELS- A PRACTICAL ENGINEER STANDPOINT V. Sigmund 1 , T. Kalman 2 and I.Guljaš 3 ABSTRACT Structural walls are common structural system in low- to medium rise buildings. Their response to earthquakes is usually favorable, but research of their seismic response has been rather limited that is manifested in a design practice. Contemporary codes allow use of nonlinear analysis for design of new buildings and evaluation of the existing ones. While nonlinear analysis is being used as standard tool for seismic design or evaluation there is a problem in modeling the nonlinear behavior of the wall structures. In this paper we have tried to provide an unbiased comparison of the results, if used by an average engineer, obtained by two different analytical approaches, three different computer codes and four different numerical models using standard values. The calculated responses are evaluated against the experimental results obtained during two European large- scale RC cantilever wall tests. Introduction The use of nonlinear time history analysis for design of new buildings and for strength evaluation of the existing ones is allowed in the Eurocode8. While linear analysis gives more-or- less comparable results, the quality of results obtained by nonlinear analysis depend on many more factors and they often can have only a vague connection to the reality. The quality of the results, sometimes, question the endeavor put into it. (If we are going to be wrong we could be it the easy way). There are various numerical models available for the analysis of wall nonlinear response during earthquake excitation. They could be divided into two main groups: microelement- (nonlinear-FEM, micro-fiber, etc.) and macro element-models (beam-column, structural-wall, etc.) models. In this paper, we modeled two reinforced/concrete cantilever walls tested on the shaking table during two European experiments and compared the measured results with the results obtained by using various numerical models. The numerical wall models used are: micro fiber element model used in ZeusNL (Elnashai, 2004.), structural-wall element model with- and without shear spring used in Ruaumoko (Athol, 2003.) and one component beam-column (wall) element model used in LarzWD (Lopez, 1988.) with the modifications (Sigmund, 2000.). The quality of numerically calculated results has been verified against the measured ones in terms of the response 1 Professor 2 Graduate Research Assistant 3 Asisstant professor, Faculty of Civil Engineering, University of Osijek, Drinska 16a, 31000 Osijek, Croatia Paper No. 418