Abstract. In this paper, a new method is proposed for identication of inelastic shear frame structures
with hesteresis, using data collected on their dynamic response. It uses the Prandtl-Ishlinskii rate
independent model for hysteresis, which was originally used in the eld of plasticity and ferromagnetism.
The proposed identication method is capable of identifying the mass, damping and restoring force of
a frame structure, which can be used in forming the equations of motion of the frame. By solving the
equations of motion, the dynamic response is predicted. The method is based on the combined use of
Quadratic Programming (QP) and Genetic Algorithms (GA). First, assuming a set of Prandtl-Ishlinskii
constants, the QP is used to nd the best frame parameters that can be used in its equations of motion to
predict its dynamic response with the minimum of error compared to the real data collected on its dynamic
response, while the GA is used to nd the best Prandtl-Ishlinskii constants for more reduction in error.
The method has been applied to dierent frames with bilinear nonlinearity where the results show the high
capability of the method. Two examples, a Single and a Multi Degree Of Freedom (SDOF and MDOF)
frame, are included in the paper.