Efficient Formulation of Physical Theory Brace Models

Concentrically braced frames dissipate severe seismic energy inputs mainly through inelastic deformations in the bracing elements. Thus, an accurate brace model is essential for improving the accuracy of the computed inelastic seismic response of braced frames. A computationally efficient formulation capable of closely predicting the hysteretic behavior of the physical theory brace models is presented. This formulation is consistent with the displacement method of analysis in the sense that it uses displacement as input. The developed brace model also involves a limited number of degrees of freedom and can be efficiently incorporated into the conventional computer programs for nonlinear dynamic analysis of structures. The developed model requires limited input data and little computer storage capacity, Comparisons are also made between the analytical predictions of the model and cyclic test results on steel struts. The results indicate a reasonable degree of accuracy in theoretical predictions. The developed brace model can be useful in nonlinear analysis and design of brace frame systems. It can also provide researchers with an efficient tool for investigating the details of nonlinear dynamic response characteristics of braced structural systems.