| This dissertation describes a framework for evaluating the energy absorbed in building structures from site-specific energy response spectra. It is based on the realization that damage to structures produced by an earthquake ground motion is not only affected by the peak seismic force or displacement, but also by the duration of the ground motion. Unfortunately, current seismic design procedures do not account for this duration-related damage.; A procedure for the development of the site-specific smooth energy response spectra for an SDOF system based on an attenuation relationship was derived from a two-stage nonlinear regression analysis. To evaluate the total absorbed energy in a multistory frame (up to 10 stories in height) from the energy spectra, equivalent SDOF systems for the first two modes were used to evaluate the energy contribution from each mode. Procedures were then developed to distribute the total energy to the structural members along the frame height. It was shown that the second-mode response needed to be considered to reflect the energy (or damage) concentration in the upper floors.; Although the proposed framework is applicable to a variety of framing systems, steel moment-resisting frames were selected in this study. To evaluate the energy capacity of the steel beams, full-scale moment connection test results were evaluated. It was shown that the energy capacity of the steel beams was affected by the connection details. Based on the available test data, the energy capacity, expressed in the form of cumulative plastic rotation, of the steel beams was developed for each type of connection details studied. The study showed that unless pre-Northridge moment connections exist in a building, steel beams usually have sufficient energy capacity. |
