A simplified model for seismic response prediction of concentrically braced frames

This paper proposes a simplified analytical model for seismic response prediction of concentrically braced frames. In the proposed approach, a multistory frame model is reduced to an equivalent shear-building one by performing a static pushover analysis. The conventional shear-building model has been improved by introducing supplementary springs to account for flexural displacements in addition to shear displacements. The adequacy of the modified model has been verified by conducting nonlinear dynamic analysis on 5, 10 and 15 story concentrically braced frames subjected to 15 synthetic earthquake records representing a design spectrum. It is shown that the proposed improved shear-building models provide a better estimate of the nonlinear dynamic response of the original framed structures, as compared to the conventional models. While simplifying the analysis of concentrically braced frames to a large extend, and thus reducing the computational efforts significantly, the proposed method is accurate enough for practical applications in performance assessment and earthquake-resistant design.