A practical method for seismic retrofit of tall buildings with supplemental damping

Current simplified design methods for buildings with supplemental damping devices are mainly based on single-degreefreedom (SDF) shear-models. Common errors of such methods are attributed to the linearization of nonlinear damping and stiffness, higher building vibration modes and flexural deformations that may be ignored in the damper design phase. In tall buildings, dampers are typically placed at certain levels only, leading to an irregular vertical damping distribution along the building height. To overcome the above-mentioned challenges, a practical multi-degree-of-freedom (MDF) performance curve tool is developed for the design of tall buildings with dampers. The method first utilizes the SDF performance curve method to design and distribute dampers along the building height for a broad range of design parameters. Then, it conducts an intermediate evaluation through response history analysis based on simplified MDF models. The emphasis is placed on the use of bilinear oil dampers for seismic retrofit applications. Dampers are represented mathematically with a Maxwell model, which accounts for the stiffness characteristics of a bilinear oil damper. Guidance is provided on the development of the MDF performance curves with simplified flexural-shear beam models. A parametric study is carried out based on a broad range of damping properties and vertical damping distribution methods. An existing 40-story steel building representing typical 1970s construction in North America is used as a benchmark in this case. It is shown that the proposed tool allows for a reliable computation of story-based engineering demand parameters for a range of available seismic retrofit design solutions.