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Study of Endurance Time Analysis Method in Seismic Evaluation of Steel Moment Resisting Frames

Tajmir Riahi, Hossein | 2009

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 39433 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Esmaeil Pourestekanchi, Homayun
  7. Abstract:
  8. In this research the capability of a new method named Endurance Time analysis in seismic assessment of single and multi degree of freedom structures in nonlinear range is investigated. Endurance Time analysis is based on time history analysis but in this method structure is subjected to an intensifying acceleration function and different damage indices of the structure are evaluated through analysis time. This method can be a useful tool for executing Performance Based Design of structures. Firstly the Endurance Time criterion is defined and the progress of the generation of Endurance Time acceleration functions is described. Also the optimization procedure used for the generation of acceleration functions with different characteristics is defined. A database of world earthquake records is collected. This database is used for the comparison of the results of Endurance Time analysis and current seismic analysis methods. Also it can be used for the generation of other acceleration functions. To compare the results of Endurance Time analysis with nonlinear time history analysis, acceleration functions are generated based on a set of earthquake records. The first step of evaluation of Endurance Time analysis results is done for single degree of freedom structures. These structures cover the range of periods between 0 to 5 seconds. Different hysteretic nonlinear models such as elastic perfectly plastic, elastic plastic with strain hardening, stiffness degrading and strength deteriorating and stiffness degrading models are used in this step. Accuracy of the results of Endurance Time analysis for single degree of freedom structures is satisfactory. The second step is to evaluate Endurance Time analysis results for steel moment-resisting frames. These frames cover the range of periods between 0.5 to 4 seconds. Results of Endurance Time analysis are compared with nonlinear time history analysis results for two sets of accelerograms. This is done for different hysteretic behavior of the connections such as elastic perfectly plastic, elastic plastic with strain hardening and strength deterioration and stiffness degrading. Also results of Endurance Time analysis are compared with the results of other seismic analysis such as pushover analysis, incremental dynamic analysis and cloud analysis. Effects of large deformations such as P-Δ on the results are also studied. A comprehensive statistical study on the accuracy of Endurance Time analysis results for different seismic intensities and their dispersion is also done. Finally some practical examples for the application of Endurance Time analysis in seismic rehabilitation of structures and performance based design of structures are presented. Based on the results, advantages and disadvantages of this method are described. Results of Endurance Time analysis for the moment resisting steel frames are compatible with the results obtained from nonlinear time history analysis. Results are more compatible for the frames that do not experience dynamic instability. Also Endurance Time analysis is more reliable than pushover analysis in predicting the distribution of engineering demand parameters in the structures
  9. Keywords:
  10. Nonlinear Time History Analysis ; Performance Based Design ; Endurance Time Method ; Damage Index ; Intensity Measure

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