Evaluation of Nonlinear Frame Finite-Element Models

Abstract

In recent years nonlinear dynamic analysis of three-dimensional structural models is used more and more in the assessment of existing structures in zones of high seismic risk and in the development of appropriate retrofit strategies. In this framework beam finite-element models of various degrees of sophistication are used in the description of the hysteretic behavior of structural components under a predominantly uniaxial state of strain and stress. These models are commonly derived with the displacement method of analysis, but recent studies have highlighted the benefits of frame models that are based on force interpolation functions (flexibility approach). These benefits derive from the fact that models with force interpolation functions that reproduce the variation of internal element forces in a strict sense yield the exact solution of the governing equations in the absence of geometric nonlinearity. While the numerical implementation of force-based models at first appears cumbersome, simple examples...