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The Application of Simplified MDOF Models for Estimating the Moment Resisting Frames Seismic Demands in Endurance Time Method

Hosseini, Mojtaba | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52649 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Esmaeil Pourestekanchi, Homayoon
  7. Abstract:
  8. Modified Fish-Bone (MFB) Model and Consistent Generic (CG) Model are simplified Multi-Degrees-of-Freedom (MDOF) models, proven to be valuable tools in estimating seismic demands of moment-resisting frames, aimed to reduce the computational costs by decreasing the number of degrees of freedom. The preliminary expansion of these simplified models for steel moment resisting frames (SMRFs) were proposed by considering elastoplastic behavior and is not able to take into account stiffness and strength deteriorations in nonlinear dynamic behavior of structures. However, behavior deterioration affects seismic demands of SMRFs under intense earthquakes. For this reason, the present study is done to improve the mentioned models by considering behavior deterioration in SMRFs and to evaluate these improved models in estimating seismic demands of steel special moment resisting frames. Furthermore, a novel simplified model called 'Consistent Modified Fish-Bone Hybrid (CMFBH) Model ' is developed to surpass the precision of all past simplified models, and to address the inappropriate adaptation of CG model geometry and the limitations of MFB model in dynamic analyses in irregular-in-span-length moment resisting frames, respectively. The Endurance Time method is applied to determine the responses of the structures under different seismic intensity levels. This method is able to determine all responses of a structure under different seismic intensity levels with a simple nonlinear dynamic analysis with appropriate precision and very low computational costs. To perform numerical analysis, the new model is applied to regular, irregular-in-height, and irregular-in-span-length Steel Special moment resisting frames located in Los Angles, US. Then, by simulating both the elementary models and the simplified ones in OpenSees software and comparing their seismic responses, their accuracy has been investigated under various levels of seismic hazard. The results show that CMFBH model is efficient in estimating the seismic demands of all three types of structures. Therefore, one can accurately estimate the seismic demands of SMRFs by using this simplified model along with endurance time method. The conjugation of these two can reduce the complexity of new generation performance based evaluation techniques
  9. Keywords:
  10. Steel Special Moment Frame ; Seismic Demand ; Modified Fish-Bone Model ; Endurance Time Method ; Consistent Modified Fish-Bone Hybrid Model ; Consistent Generic Model

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