Analytical and experimental response of asymmetric structures with frictional and viscoelastic dampers

This article summarizes analytical and experimental results of linear asymmetric structures with frictional and viscoelastic dampers. Such energy dissipation devices may prove useful in controlling the uneven deformation demand occurring in structural members of torsionally unbalanced structures. Torsional balance is defined as a property of an asymmetric structure that leads to similar deformation demand in structural members equidistant from the geometric center of the building plan. It can be defined in a strong or a weak form. The latter, which allows for rotation of the building plan, only implies an equal norm of the displacement demand at resisting planes symmetric with respect to the geometric center. In general, it can be achieved by the use of energy dissipation devices by making the so-called empirical center of balance of the structure to lie on top of the geometric center. Shaking table results conducted on a mass and stiffness asymmetric six-story model with frictional dampers support the analytical results and the concept of weak torsional balance. Similar results may be extended to the use of viscoelastic dampers as well as for inelastic multistory asymmetric structures.