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Seismic Assessment of Steel Low-Rise Structures with Hat Knee Bracing System and Irregularities in Height

Tavakoli Targhi, Amir Ali | 2021

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 54437 (53)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Mofid, Masoud
  7. Abstract:
  8. Seismic resistant structural systems or lateral load-bearing systems must enjoy adequate resistance and hardness against lateral forces and displacements in addition to resisting large deformations to absorb and dissipate energy. Since Iran is located in a seismic area and almost all metropolises of Iran are located in the vicinity of faults, it is critically important to pay close attention to development and application of efficient seismic systems in the constructional system of Iran. The HKB (Hat Knee Bracing) system is a lateral load-bearing system, the construction of which is inspired from divergent bracing systems. In other words, as in Eccentric Braced Frames (EBF), there is a ductile element or fuse in which a significant amount of the energy and deformations reaching the frame during the earthquake has been accumulated; therefore, other parts and components of frame are subjected to less seismic forces and tolerate less damage. In HKB system, this ductile element is the hat knee components of the system, leading to superiority of HKB systems compared to EBF systems in terms of replacement and ease of post-seismic rehabilitation operations. Only a few studies have been conducted on the seismic behavior and performance of various bracing structures with HKB system hitherto. For this purpose, this study was carried out to investigate the effectiveness and compare the behavior of steel framed structures with irregularity in height of frames in two statuses including with and without the application of HKB system during the earthquake. To fulfil the objectives of the study, models of five- and seven-story steel frames were designed in the environments of the powerful SAP2000 and OpenSees software. The performance of the steel frames with HKB system was investigated by carrying out nonlinear static (pushover) and incremental nonlinear dynamics analyses. To perform the incremental dynamic analysis, the studied models were subjected to seven accelerometers near and far from the fault field (a total of 14 different records) logged from various earthquakes occurred worldwide. The findings of this study indicated that employing HKB system significantly increased the lateral load-bearing capacity of steel frames compared to moment frame system such that failure occurred at a larger seismic level
  9. Keywords:
  10. Incremental Dynamic Analysis ; Pushover Analysis ; Knee Brace ; Seismic Assessment ; Moment Steel Frames ; Eccentrically Braced Frame (EBF) ; Vertical Irregularity

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