Seismic Retrofit of Coupled Hospitals with Viscous Dampers

Seismic Retrofit of Coupled Hospitals with Viscous Dampers

When seismically retrofitting existing hospitals, in addition to achieving the desired structural seismic performance, there are certain special requirements that should be taken into consideration, such as accommodating the original structural configuration and space, minimizing the impact on daily operation and patients during the reconstruction period, and guaranteeing the functionality of housed critical medical equipment. A seismic retrofit strategy is thus proposed that involves external connections via linear viscous dampers that have efficiently distributed damping coefficients. Two installation approaches are examined and discussed: damper connections for each story and damper connections for just the lower stories. Three damping coefficient distribution methods are discussed and examined: uniform distribution across all stories, a distribution based on the kinetic energy of all stories, and a more efficient distribution based on the kinetic energy of critical stories. The numerical results show that improper design of the installed reaction structures and linked viscous dampers can be precluded by eliminating those that fall within undesired frequency ratio bands. The three distribution methods are shown to be able to satisfactorily control the seismic response of existing hospitals, and the third distribution method based on the kinetic energy of the critical stories is shown to be the most cost-effective.