ارزيابي رفتار ديوار برشي فولادي با بازشو تقويت‌شده

Evaluation of the Behavior of Steel Plate Shear Wall with Stiffened Opening

در اين پژوهش به بررسي تاثير بازشوهاي مستطيلي تقويت‌شده در مقاومت، سختي اوليه، شكل‌پذيري و ظرفيت جذب انرژي ديوارهاي برشي فولادي پرداخته شده است. با هدف كاهش تعداد اعضا تقويتي در لبه‌ي بازشوها و صرفه‌ي اقتصادي بيشتر، بازشوها در كل ارتفاع طبقه فرض شده است. در مطالعات، اثر نسبت طول دهانه به ارتفاع طبقه‌ي مدل‌ها و مشخصات بازشوها (طول و موقعيت بازشو) در نظر گرفته شده است. نتايج نشان مي‌‌دهد كه در نتيجه‌ي ورود بازشو، مقاومت ورق متناسب با كاهش در سطح مقطع آن كاهش مي‌يابد، درصورتي كه به‌دليل حضور المان‌هاي تقويتي به مقاومت قاب همواره افزوده مي‌شود. درنتيجه، مقاومت كل سيستم بسته به موقعيت و طول بازشو مي‌تواند كاهش يا افزايش يابد. سختي و شكل پذيري سيستم‌ها نيز همواره با ورود بازشو كاهش مي‌يابد، اما درصورتي كه ابعاد بازشو قابل توجه نباشد، ظرفيت جذب انرژي در سيستم مي‌تواند بدون تغيير و يا با افزايش همراه باشد.

In this paper, the behavior of steel plate shear walls (SPSWs) with stiffened rectangular openings used as windows or doors in buildings is studied using the finite element method, and compared with corresponding systems without openings. In the case of such large openings, the use of local boundary elements (LBE) around the opening to anchor and transmit the infill plate tension forces to the surrounding boundary members (beams and columns) at their ends is inevitable. It is found to be more economical to extend the opening to the story height, whether needed or not, so that horizontal local boundary elements will not be needed, and which would lead to considerable cost saving in construction. Therefore, the openings are assumed to have a constant height and extend along the full height of the systems. A number of single-story SPSWs, with different aspect ratios, having four different opening location patterns and various opening lengths, are considered for this research. According to the design code recommendations, SPSWs are designed per the capacity design principle. The adequacy of the finite element modeling approach for representing the pushover and cyclic responses of SPSWs is verified through comparisons with experimental results. Results show that due to the introduction of openings and LBE, plate strength decreases proportionally with the decrease in plate area, while the frame strength always increases. As a result, the overall system strength may increase or decrease, depending on the location and length of the opening. The stiffness and ductility of SPSWs with stiffened openings are always less than those of the corresponding SPSWs without openings, and, generally, the ratios of the stiffness and ductility values of SPSWs with openings to those of corresponding SPSWs without openings decrease linearly with the relative length of the openings. The system aspect ratio has no significant effect on the ratios of the strength, stiffness and ductility of SPSWs with openings compared to those of the corresponding SPSWs without openings. Moreover, provided that the opening length is not very long, the introduction of openings and LBE increases the energy dissipation capacity of the system.