Modelling of the panel zone in steel and composite moment frames

This paper deals with the modelling of the panel zone region within beam-to-column connections in steel and composite moment-resisting frames. Existing analytical models for representing the panel zone response are first reviewed and their scope and limitations are discussed. A new approach, which is particularly suited for modelling steel and composite joints within frame analysis procedures, is then proposed and described. The method rationally accounts for the effect of different boundary conditions, as well as shear and flexural deformation modes, in evaluating the elastic and inelastic response. Validation of the proposed approach is carried out through comparisons against available experimental results in addition to more detailed continuum finite element analyses. The results demonstrate that the approach developed provides a more realistic representation of the behaviour in comparison with available models, especially in the case of composite connections. It is shown that, for composite joints, commonly used simple moment-distortion relationships may not be adequate. This is primarily due to the dependency of the behaviour on the internal force distribution at the joint. The study describes the implementation of the suggested approach within frame analysis procedures, and substantiates the important role played by the panel zone in the response of moment frames under lateral loading conditions.