اثر محل بازشوي متمركز در كاهش ظرفيت برشي ديوارهاي برشي فولادي

EFFECT OF DIFFERENT POSITIONS OF CONCENTRATED OPENINGS ON THE SHEAR CAPACITY OF STEEL PLATE SHEAR WALLS

پتانسيل بالاي ديوارهاي برشي فولادي در جذب انرژي و شكل‌پذيري زياد آنها باعث شده است كه جهت تحمل بارهاي جانبي، به ضخامت‌هاي بسيار كم به خصوص در طبقات فوقاني سازه نياز داشته باشند، كه در محاسبات گاهي به كسري از ميلي‌متر مي‌رسد. از آنجا كه ممكن است ورق‌هاي فولادي با چنين ضخامت‌هايي در بازار موجود نباشد، استفاده از ورق با ضخامت بالاتر از نياز طراحي، ولي با ايجاد بازشو براي كاهش سختي، يكي از راه‌حل‌هاي منطقي است. از سوي ديگر، وجود بازشو به لحاظ ملاحظات معماري نظير تعبيه‌ي پنجره و نورگيري امري بديهي و اجتناب‌ناپذير است. در اين نوشتار، ظرفيت برشي ديوار برشي فولادي در اثر وجود بازشو در نقاط مختلف، به كمك روش اجزا محدود مورد بررسي قرار گرفته و درنهايت، رابطه‌ي نيمه تجربي و بي‌بُعدشده جهت تخمين دقيق ميزان كاهش مقاومت ديوار با بازشو در هر نقطه‌ي دلخواهي از ورق ارايه شده است.

The great efficiency of steel plate shear walls (SPSW) and their deformability have caused them, by coercion, to be very thin in thickness in order to resist the lateral seismic loads, especially in upper stories of the building which may be a fraction of a millimeter, and this steel plate thickness meeting the design requirements may not be available on the market. On the other hand, using the thicker plate than the designed ones would increase the shear capacity of the wall, and ultimately increase the transferred load to surrounding members so that the beams and columns would need to be bigger in section. Hence, one of the rational solutions is to use the thicker plate while improvising the opening in plate in order to reduce the stiffness of the panel. On the other hand, embedding windows and openings are inevitable due to architectural requirements. According to several research studies and experiments, concentrated circular opening located in the center of the plate has the greatest effect on reducing the stiffness and the shear resistance capacity of the panel and use of this amount of decrease in resistance to other openings would be conservative. This paper investigates the shear behavior of steel plate shear panels with an opening in an arbitrary position and tries to find a mathematical relationship (if any) between the percentage of decrease in strength of the wall and its correspondence with the position of the opening with the aid of a series of finite element analyses using ANSYS. At the beginning, the unstiffened panel was modeled by comparing the results of the analysis with the related classical equations and experimental tests and having calibrated the errors, the process of creating holes in different positions went on for up to fifteen models, and finally, the corresponding equations for the percentage of decrease in strength of panels were obtained which were independent from the dimensions of the panel. Ultimately, the validity of the proposed equations was examined by some re-modeling within the examined plate, and the results confirmed the proposed equations in a very favorable manner.