Effect of building nonlinearity on seismic response of nonstructural components: A parametric study

An extensive parametric study is conducted with eight code-designed steel moment-resisting frames and a series of linear and nonlinear single-degree-of-freedom nonstructural components to investigate to what degree, how often, and under what conditions the nonlinear behavior of a building may amplify the seismic response of a nonstructural component attached to it. The study comprises the time-history analysis of each of the considered frames with one of the considered nonstructural components connected to it. In each case, an ensemble of 25 recorded earthquake ground motions is used, alternatively scaling them to three different intensity levels. The study also comprises a comparison between the nonstructural component responses obtained when the supporting structure is modeled alternatively as a nonlinear and a linear system. The influence of the nonstructural component location, nonlinearity, and damping ratio and the relative values of the building and component masses and natural frequencies is investigated. It is found that, in general, the nonlinear behavior of the supporting structures reduces the seismic response of the nonstructural components in comparison with the linear counterparts. In a few cases, however, the nonstructural component response is amplified by a factor that can be as large as 5.2. These cases correspond to components located on the lower building floors, with a natural period equal to the second or third natural period of the building, and subjected to a narrow-band excitation with a dominant period close to the building's fundamental natural period.