طرح سيستم ديوار برشي فولادي براساس نياز جابجايي غيركشسان

Design of Steel Plate Shear Walls, Based on Inelastic Displacement Demand

امروزه با وجود گسترش استفاده از ديوارهاي برشي فولادي، طراحي آنها در آيين‌نامه‌ها هنوز براساس روش‌هاي نيرويي است. روش‌هاي نيرويي به‌دليل درنظرنگرفتن رفتار غيركشسان به‌تدريج جاي خود را به روش‌هاي طراحي براساس عملكرد داده‌اند. يكي از اين روش‌ها، روش طرح خميري براساس عملكرد است، كه يكي از پارامترهاي اوليه‌ي طراحي در آن، پارامتر تعيين مقدار رانش تسليم سازه است، كه در اغلب مطالعات با كاستي‌هايي همراه بوده است. در اين نوشتار ضمن ارايه‌ي روش طراحي مذكور براي سازه‌هاي با ديوار برشي فولادي بدون سخت‌كننده، روشي براي تعيين مقدار رانش تسليم سازه نيز ارايه شده است. لذا جهت كنترل، 6 سازه‌ي 5 و 10 طبقه با شكل‌پذيري‌هاي متفاوت با زلزله‌ي طرح آيين‌نامه‌ي 2800 ايران طرح شده است. با تحليل غيرخطي استاتيكي سازه‌ها مشاهده شده است كه شكل‌پذيري هدف و شكل‌پذيري واقعي سازه‌ها به هم نزديك است. همچنين عدم اصلاح مقدار رانش تسليم سبب ايجاد خطا در طرح خواهد شد.

Over the past few years, unstiffened steel plate shear (SPSW) has been used as a lateral load resisting system, due to its proper behavior against earthquake. The designing procedure in seismic codes for these systems is still based on the elastic force-based method. Nowadays, the inelastic behavior in these methods is gradually being replaced with performance-based seismic design (PBPD) methods. One of these methods is performance based plastic design (PBPD). The design concept in this methodology is based on performing a desired yield mechanism in the structure and an inelastic target displacement. In this procedure, determination of the inelastic design base shear structure requires basic assumptions and an iterative process to achieve the intended performance (target displacement). One important basic design parameter is to determine the initial structure yield drift which has been associated with some inadequacy in most studies. In this paper, the design methodology for an unstiffened steel plate shear wall system has been developed, and a simple method to determine the amount of structure yield drift has also been proposed. This design methodology had already been checked for 6 structures with five and ten stories and 3 different target ductility values (2 , 3 and 4) under a design level earthquake, based on the Iranian earthquake code (Standard 2800). Inelastic static analysis (Pushover) of designed structures based on this method reveals that the actual ductility of structures is close to the assumed target ductility and the actual yield mechanism is the same as the assumed yield mechanism. Based on the test results, the yield drift value is different in each structure, and, to achieve the correct design, iteration methods are essential to yield drift convergence in the design process. In addition, results showed that the proposed method for determination of structure yield drift is very quick and reliable for use in the design procedure. Over the past few years, unstiffened steel plate shear (SPSW) has been used as a lateral load resisting system, due to its proper behavior against earthquake. The designing procedure in seismic codes for these systems is still based on the elastic force-based method. Nowadays, the inelastic behavior in these methods is gradually being replaced with performance-based seismic design (PBPD) methods. One of these methods is performance based plastic design (PBPD). The design concept in this methodology is based on performing a desired yield mechanism in the structure and an inelastic target displacement. In this procedure, determination of the inelastic design base shear structure requires basic assumptions and an iterative process to achieve the intended performance (target displacement). One important basic design parameter is to determine the initial structure yield drift which has been associated with some inadequacy in most studies. In this paper, the design methodology for an unstiffened steel plate shear wall system has been developed, and a simple method to determine the amount of structure yield drift has also been proposed. This design methodology had already been checked for 6 structures with five and ten stories and 3 different target ductility values (2 , 3 and 4) under a design level earthquake, based on the Iranian earthquake code (Standard 2800). Inelastic static analysis (Pushover) of designed structures based on this method reveals that the actual ductility of structures is close to the assumed target ductility and the actual yield mechanism is the same as the assumed yield mechanism. Based on the test results, the yield drift value is different in each structure, and, to achieve the correct design, iteration methods are essential to yield drift convergence in the design process. In addition, results showed that the proposed method for determination of structure yield drift is very quick and reliable for use in the design procedure.