Damping of Frames with Constrained Viscoelastic Layers

The damping of a steel braced frame with a vertical layer of visco-elastic material is quantified by computing steady-state responses to harmonic lateral loadings. Viscoelastic constitutive equations are used to model all materials. It is found that the constrained viscoelastic layer significantly increases the damping of the frame while causing a tolerable loss in lateral stiffness. The static behavior of the frame is found to be analogous to that of coupled shear walls. It is observed that weighing each material's damping contribution by its strain energy and summing contributions to obtain the total damping, significantly overestimates the true damping of the composite frame. In general, it is determined that such a method is inappropriate for series systems in which some materials are highly damped while others are only slightly damped. Issues other than damping which relate to the feasibility of the concept are briefly considered.