Insights on Higher-Mode Effects in High-Rise Buildings with Flexible Base Rotational and Translational Restraints: A Theoretical Study Using a Continuum Beam Analogy

High-rise buildings are sensitive to higher-mode effects that can significantly magnify the seismic response of these structures. An uncoupled rocking and shear mechanism system that introduces nonlinearity in both flexure and shear at the base of high-rise structures has been proposed and validated as being efficient in mitigating higher-mode effects and achieving low-damage design. In this paper, structures with base flexural and shear mechanisms are idealized using continuum cantilevers with flexible rotational and translational restraints. Modal analyses of these cantilevers provide insights on how higher-mode effects in high-rise buildings are affected as the base restraints are varied in their fixity.