Fiber reinforced polymer panels for attenuating floor accelerations in a hospital structure

This paper addresses the analysis and experimental investigation of PMC panels utilized for seismic and vibration mitigation. The concepts rely on introducing considerable shear deformation at strategically located layers. The layers at which the shear deformation to take place, referred to here as the interface layers, are composed of a combination of solid visco-elastic material combined with honeycomb material. As part of this research, a series of experiments were performed to quantify the energy dissipation characteristics of the interface layer. The effects of thickness, loading rate, and the ratio of the volume fractions of the constituent materials are investigated. Utilizing the results obtained from material testing, three conceptual panel designs were tested to assess the over all energy dissipation in a structural system. The main advantage of these panels is that they can reduce floor response in a structural system. As such for Hospital structures, the concern is to reduce the floor responses to mitigate damage to nonstructural components that are motion sensitive. In this research, the conceptual designs of the panels are employed in a benchmark hospital building-namely, the Multidisciplinary Center for Earthquake Engineering Research (MCEER) demonstration hospital structure. Nonlinear 3D finite element analyses were carried out to evaluate the effective damping of added PMC composite panel with viscoelastic interface layers in the retrofitting of the MCEER's demonstration hospital structure. An equivalent Kelvin model consisting of an elastic spring and a linear viscous damper combined in parallel is proposed to represent the FRP composite panel with viscoelastic interface layers. The retrofitted structure was subjected to MCEER west coast ground motions. Significant increase in the system damping was observed with the added PMC composite panels. Both the modal strain energy method and logarithmic decrement method showed the PMC composite panel contributed 8% damping to the hospital structure. Time history analyses results showed that the peak floor displacement and acceleration response were reduced significantly and the vibration damped out very quickly.