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Evaluation of Energy-Based Modal Pushover Analysis in Reinforced Concrete Structures,with Elevation Irregularity

Hashemi, Mohammad Javad | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39430 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Mofid, Masoud
  7. Abstract:
  8. The method of nonlinear time history analysis is well known as one of the most accurate techniques in seismic analysis of structures. However, this method needs much effort in terms of required data and computational cost. Within the time constrains of design consulting firms, more simple analysis tools are also desirable. One of the simple methods which have been gaining ground, as an alternative to time history analysis, is nonlinear static pushover analysis. In this method, the capacity curve of the structure with respect to the roof displacement is established. In nonlinear static pushover analysis, disproportionate increases in the roof displacement and even outright reversals the higher modes can also distort the capacity curve of the equivalent single degree of freedom system. To overcome this problem, recently, "Energy-Based" Modal Pushover Analysis (MPA) method has been introduced. In this method, the absorbed energy and/or the external work in the pushover analysis is considered. Accordingly, the assessment of Energy-Based MPA method is important in seismic analysis of asymmetrical and tall buildings. In this paper, the seismic demands of concrete structures with disparity in elevation are determined, using Energy-Based MPA. For the assessment of the presented technique, the results are compared with those from the Non-Linear Time History Analysis (NL-THA). Seven examples including 2-D simulation of 12-story building are modeled, using Opensees Code. For each case, a different type of irregularities such as mass, geometry and variations due to the difference in elevation, is considered. Story-drifts and floor-displacements are used as the main parameters for assessment of the results. Based on the study of structural performance of the models, it has been cleared that different types of above-mentioned disparity in elevation, does not have any significant effect on Energy-Based MPA method. Consequently, this method can be considered as an accurate alternative technique for NL-THA to fairly estimate the seismic demands of structures
  9. Keywords:
  10. Time History Analysis ; Static Pushover Analysis ; Modal Pushover ; High Buildings ; Concrete Building ; Energy-Based Model Pushover Analysis

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