Consideration of pounding and SSI in energy-based seismic design of buildings

Abstract

The energy demand on a given construction is commonly determined, in terms of equivalent velocity, from smoothed design spectra that are ordinarily derived after dynamic analyses on SDOF systems. The application to actual multi-story buildings is far from trivial, given that their behavior must be characterized with MDOF models; in this context, a relevant issue is the distribution of energy along the building height. In other words, additional research is required to further promote the development of the energy-based approach. Thus, this work addresses two issues not sufficiently covered in past studies: the influence of soil-structure interaction (SSI), and pounding between adjoining buildings. The study begins by selecting four low-rise (3 and 5-story) RC frame buildings and four representative severe ground motion records (i.e. historic accelerograms). Such inputs are selected with respect to their most relevant characteristics: frequency content (indirectly represented by the soil type) and relevance of velocity pulses (forward-directivity effects). Then, 2-D nonlinear dynamic analyses are performed on single (lone) buildings and on pairs of colliding buildings. These calculations provide the total input and hysteretic energy and their distribution among the building stories. Such results are compared with those from a more simplified approach (i.e. the individual energy spectra of the considered inputs), and relevant conclusions are derived. Preliminary results show that the comparison between the energies determined with the two abovementioned approaches shows a reasonable fit, and that the influence of SSI proves significant. Regarding pounding, it does not alter significantly the total input and hysteretic energy, but their distribution among the floors changes considerably, concentrating in the colliding floors.

Postprint (published version)