Loading...

Investigation of Soil-Structure Intraction Effects in Optimal Seismic Retrofit of Steel Frames with Viscous Dampers Using Endurance Time Method

Sarcheshmehpour, Mohammad | 2012

503 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43541 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Esmaeil Pourestekanchi, Homayun; Ghannad, Mohammad Ali
  7. Abstract:
  8. Performance-based seismic design method, with a new look and a totally different philosophy, as an alternative design method instead of strength-based design method has been suggested in the new generation of seismic codes. Massive problems such as the need for complex dynamic analysis and consequently, spending high cost and time in researches forced researchers to seek more effective methods to evaluate seismic performance of structures. This idea in the optimal design of structures that require repeated analysis seems to be more effective. In the Endurance Time (ET) method, structures are subjected to specially designed intensifying acceleration functions and their response at various excitation levels is estimated by each single response-history analysis; thus, significantly reducing the required computational demand. Also the effectiveness of this method will be highlighted in seismic performance based design and performance-based optimal seismic design of structures. Soil-Structure interaction changes behavior of soil-structure systems from behavior of fixed base structure, moreover alters the linear and nonlinear behavior and design of structures that each of them can be useful or non-advantageous. In this thesis, optimal retrofit of steel moment resisting frames that each of them has been designed with weakness, with viscous dampers has been investigated; also the effect of soil-structure interaction on the optimal placement of viscous dampers in the structure stories and retrofit trend has been studied. Different moment resisting frames with nonlinear behavior in both soil-structure and fixed base systems have been modeled in OpenSees software and in each model optimal placement of viscous dampers in the height of structure has been determined by Genetic algorithm that the structure can satisfy all the codes performance limitations with minimum costs. Endurance Time method for seismic evaluation of the frames has been used and the accuracy of the method has been confirmed by analysis of frames under natural earthquake motions. ASCE41-06 regulation is employed as a measure for performance-based design. In low magnitude earthquakes, Maximum inter-story drift ratio is reduced as the soil structure interaction is considered in modeling, on the other hand by increasing the magnitude of earthquake, upper stories’s drift ratios of structure in soil-structure system will gradually increase than the upper stories’s drift ratios of fixed base system. Generally, soil-structure interaction reduces the summation of damping coefficients which is obtained from optimization. But it can not be concluded that the use of fixed base optimal damper placement is always conservative. In almost all cases, Endurance time excitation functions has been provided a good prediction of the behavior of frames in both systems of fixed base and soil- structure subjected to earthquake motions
  9. Keywords:
  10. Optimization ; Soil-Structure Interaction ; Viscous Damper ; Genetic Algorithm ; Performance Based Design ; Endurance Time Method

 Digital Object List

  • ارزيابي اثرات اندركنش خاك و سازه در بهسازي لرزه اي بهينه قاب هاي فولادي با استفاده از ميراگرهاي ويسكوز و تحليل زمان دوام
  •   view
  •   download

 Bookmark

No TOC