كليدواژه :
پانل برشي فولادي , قاب برشي فولادي , سخت كننده عرضي , پارامترهاي لرزه اي
چكيده فارسي :
سيستم لوله اي يكي از سيستم هاي باربر جانبي در سازه هاي بلند مي باشد كه ستون ها در فواصل نزديك به هم از طريق اتصالات خمشي تيرهاي عميق به يكديگر در پيرامون ساختمان متصل مي شوند. ولي با توجه به حداقل محدوديت هاي آيين نامه اي در مورد نسبت طول دهانه آزاد به ارتفاع كلي تير، امكان استفاده از اين سيستم وجود ندارد. لذا ايده استفاده از قاب هاي برشي فولادي همراه با تيرهاي غيرمنشوري به عنوان يك جايگزين پيشنهاد شده است. در قاب هاي برشي با توجه به چيدمان سخت كننده هاي عرضي تير پيوند (فيوز برشي)، ظرفيت باربري جانبي مي تواند از طريق مقاومت كمانشي، مقاومت پس كمانشي ناشي از عمل ميدان كششي و يا ظرفيت باربري ناشي از تسليم ورق جان تامين گردد. لذا تاثير چيدمان سخت كننده بر روي متغيرهاي عملكرد لرزه اي قاب هاي برشي شامل ضريب رفتار، ضريب اضافه مقاومت و ظرفيت دوران با نسبت هاي طولي مختلف تير پيوند كه رفتار همگي كنترل شونده توسط برش مي باشند با استفاده از تحليل هاي اجزاء محدود بررسي شده است. در انتها نيز متغيرهاي ضريب رفتار و ضريب اضافه مقاومت در قاب هاي 3، 5، 7، 10، 15 و 20 طبقه براساس فاصله سخت كنننده بهينه براي يك نسبت طولي مشخص ارايه و به منظور سهولت در مدل سازي قاب هاي چند طبقه در نرم افزارSAP2000، پارامترهاي مدل سازي و معيارهاي پذيرش معرفي و با نتايج اجزاء محدود مقايسه شده است. همچنين در انتها يك سازه 25 طبقه با دو سيستم باربر جانبي مختلف شامل قاب خمشي لوله اي و قاب برشي با يكديگر مقايسه شده است.
چكيده لاتين :
Structures designed to resist moderate and frequently occurring earthquakes must have sufficient stiffness and strength to control deflection and prevent any collapse. Since stiffness and ductility are generally two opposing properties; it is desirable to devise a structural system that combines these properties in the most effective manner without an excessive increase in the cost. Steel structural systems including moment resisting and concentrically braced frames have been widely used to resist earthquake loads. Concentrically Braced Frames (CBFs) have high stiffness, and due to the probable buckling of their diagonal members, are not ductile enough. Versus, Moment-Resisting Frames (MRFs) have adequate ductility as their beam sections can undergo inelastic deformations. However, due to the low stiffness of moment frames, the construction costs will be increased. In recent decades, steel shear panels are utilized as one of the lateral resistant systems, in Steel Plate Shear Walls (SPSWs), and the link beam of steel frames with eccentric bracing to achieve the aim of shear performance and keep the adjacent members in the elastic range. The Tubular frame is one of the common lateral resistant systems in which the columns are placed in close spaces and connected through deep MRF beams around the building perimeters. Based on the new design codes, the minimum limit of span-to-depth ratio (7 for moderate moment-resisting frames and 5 for special moment-resisting frames) is not satisfied at tubular system. So the idea of Shear Resisting Frames (SRFs) with non-prismatic beams connected by a shear fuse in the middle of the span was proposed as one of the alternatives. Using SRFs remove these limitations and increase the energy dissipation capability. In this new concept, the shear force in the beam is considered as the displacement-controlled component of the system. Similar to eccentrically braced frames (EBFs), the link is tuned as a sacrificial component so that the seismic energy is dissipated by shear yielding in a small segment in the middle of the beam. According to the stiffeners layout, lateral loading capacity in SRFs usually is achieved through buckling strengths or post- buckling capacity resulted from tension field action or load carrying capacity from the yielding of the web plates. So stiffeners play a crucial role in the lateral loading capacity of shear resisting frames and have a significant effect on the energy dissipation capability. Following this issue, the effect of transverse stiffeners with different layouts and placements (various spaces and two or one-sided arrangement) on the seismic performance parameters (response modification factor, overstrength factor and rotation capacity of link beam) of steel shear frames with different link length ratios where all of them are controlled with shear behavior, are evaluated by finite element cyclic and pushover analysis. At the end, an optimum space is proposed for different link length ratios and the response modification factors and overstrength factor of multi-story shear resisting frames including 3, 5, 7, 9, 10, 15, and 20-story for a specific link length ratio are presented. Also for facilitating the modeling process of multi-story SRFs in SAP2000 software, modeling parameters and acceptance criteria were extracted from cyclic and monotonic curves. Finally, pushover curves from SAP2000 were compared to ABAQUS to validate these parameters. At the end, a 25-story building with two different lateral resisting systems including tubular frame and SRFs were compared.
