- مبلغ: ۸۶,۰۰۰ تومان
- مبلغ: ۹۱,۰۰۰ تومان
A procedure is proposed whereby input and hysteretic energy spectra developed for single-degree-of-freedom (SDOF) systems are applied to multi-degree-of-freedom (MDOF) steel moment resisting frames. The proposed procedure is verifi ed using four frames, viz., frame with three-, fi ve-, seven- and nine-stories, each of which is subjected to the faultnormal and fault-parallel components of three actual earthquakes. A very good estimate for the three- and fi ve-story frames, and a reasonably acceptable estimate for the seven-, and nine-story frames, have been obtained. A method for distributing the hysteretic energy over the frame height is also proposed. This distribution scheme allows for the determination of the energy demand component of a proposed energy-based seismic design (EBSD) procedure for each story. To address the capacity component of EBSD, a story-wise optimization design procedure is developed by utilizing the energy dissipating capacity from plastic hinge formation/rotation for these moment frames. The proposed EBSD procedure is demonstrated in the design of a three-story one-bay steel moment frame.
10 Summary and conclusion
To apply energy-based seismic design procedures to MDOF systems, the input and hysteretic energy spectra developed for SDOF systems need to be extended. In this paper, a procedure for estimating input and hysteretic energies for MDOF systems from equivalent SDOF systems was proposed and verifi ed. Furthermore, a distribution scheme for distributing the hysteretic energy over the height of a multistory steel moment frame was proposed. The proposed scheme is based on work done by the modal forces as they act through the corresponding story displacements, and requires the designer to compute the modal forces for each mode using any existing procedure, apply these forces to the frame, and calculate the displacements due to these modal forces. A comparison of this proposed hysteretic equation with the actual hysteretic energy distribution from a pushover analysis showed that the proposed equation gave rather good results.