Seismic floor acceleration and energy absorption analysis on concrete framed buildings with typical retrofitting and dampers

Here is analyzed the seismic performance of typical 15-story framed buildings of reinforced concrete in original state and retrofitted with different stiff solutions and combined with passive dampers by fast nonlinear time-history analyses. The investigated conventional retrofitting solutions are infill masonry walls, diagonal/Chevron braces, rigid cores and passive dampers (fluid viscous and solid viscoelastic). It is compared the floor shear/bending distribution, peak floor acceleration, seismic energy dissipation and device's hysteretic performance. The flexible behavior of the unretrofitted building was corrected with stiff retrofitting solutions, but, conversely, the peak floor accelerations were amplified (25-64%). Compared to conventional stiff solutions, the dampers allowed a reduction of distortions (floors 2-12), where the original building showed excessive flexibility. Viscoelastic dampers exhibited acceleration reductions on floors 4-12 (43%) and amplifications on top floors (15%). Conversely, fluid viscous dampers showed more acceleration reductions on almost all floors of about 55% and less amplifications on top floors. The presented results allowed to compare the floor acceleration flow with the use of stiff retrofitting solutions and the dissipation of the acceleration with the use of fluid viscous and solid viscoelastic dampers in strategic locations, as well as the energy dissipation capability of the devices. The energy absorption effectiveness of the dampers depended on the location, number of devices, shear forces and peak floor accelerations flow, especially when analyzed without dampers (only with stiff retrofitting). Fluid viscous dampers showed a better performance in terms of seismic energy absorption if compared to the combinations with viscoelastic dampers.