الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Steel Moment Resisting Frames (MRFs) are one of the most commonly used lateral load resisting systems since the dawn of high-rise construction. the 1994 Northridge earthquake, an earthquake that nearly injured a quarter-million people, was one of the milestones in shaping the way we currently design MRFs. Since 1994, moment frames were extensively experimented and analyzed to stand on the reasons behind connection failures which were caused by the earthquake and to improve the ductility of moment resisting frames. Considering that the mean plastic rotation for subassemblies designed before Northridge is 0.005 rad, which is one-sixth of the specified value of 0.03 rad. Panel zone, as a part of a steel moment resisting frame, is that portion of the frame whose boundaries are within the rigid connection of the beam and the column. It is prominent to acknowledge the contribution of the panel zone to the total energy dissipation of moment resisting frame (MRF), with respect to the other two components: beam and column. In general, shear yielding in a panel zone is its main source of energy dissipation, whereas flexural yielding is the main source of energy dissipation in the beam. If properly designed, the panel zone can contribute to more than 50% of the total energy dissipated. Current design guidelines recommend the balanced design of the panel zone. Although weak panel zones can effectively contribute to the overall connection ductility and reduce the beam plastic rotation, the use of a weak panel zone can also increase the risk of brittle and/or ductile fraction at higher connection plastic rotation(ElTawil et al., 1999; Gupta & Krawinkler, 1999). Moreover, a strong panel zone will remain elastic with low connection ductility, while increasing the demand of the beam plastic rotation to achieve the required story drift (Kim & Lee, 2017; Shin, 2017). The effect of the panel zone surrounding elements (column-flange thickness, beam-web slenderness ratio, and panel zone aspect ratio) on the panel zone shear strength has not been thoroughly studied. Where, different studies have shown that the AISC design equation for calculating the nominal panel zone shear force overestimates the connection shear strength, especially in thick column flanges. The main objectives of this study are to evaluate the effect of column flange thickness (CFT) and beam-web slenderness ratio (BSR) on the panel zone shear strength and to present a modified design equation to better predict the nominal shear strength of the panel zone. The investigation in this study is based on a parametric study (more than 1300 subassemblies), which is designed using current design guidelines. The finite element models used in this study are validated using a physical experiment and the validation shows a good fit with the test in terms of stiffness, maximum strength, total energy dissipation, and the contribution of each subassembly component (panel zone, beam, and column) to the total story drift and the total energy dissipation. Moreover, non-linear regression is used to propose modifications to the AISC design equation in both yield and plastic panel zone shear strength. The study demonstrates the considerable effect of the panel zone surrounding elements on the calculation of the panel zone shear strength. Besides, the proposed design equation shows considerable accuracy in estimating the panel zone shear strength at yield and plastic limits