مطالعه‌ي آزمايشگاهي و تحليلي سيستم مهاربندي همگراي مركب با پانل برشي فولادي

EXPERIMENTAL AND ANALYTICAL STUDY ON CONCENTRICALLY BRACED FRAME SYSTEM COMBINED WITH STEEL SHEAR PANEL

تحقيقات گذشته نشان داده اند كه ورق‌هاي نازك فولادي در برش عملكرد مطلوبي دارند كه با توجه به اين ويژگي، از اين مكانيزم در سيستم هاي مقاوم جانبي مانند ديوار برشي فولادي استفاده مي شود. در اين مطالعه، براي بهبود عملكرد لرزه‌يي قاب‌هاي مهاربندي همگرا از پانل برشي فولادي استفاده شده است. از اين‌رو، يك سيستم تركيبي توسعه‌داده‌شده و رفتار غيرخطي آن به‌صورت تحليلي و آزمايشگاهي بررسي شده است. در اين مطالعه‌ي آزمايشگاهي، يك مدل پانل برشي يك طبقه با اتصال مفصلي اعضاي مرزي در 4 گوشه‌ي قاب و همچنين اتصال پيچي اعضاي مرزي به ورق پركننده انتخاب شده است. نمونه‌ي مورد بررسي تحت بارگذاري شبه‌استاتيكي سيكلي در امتداد قطري قرار گرفت. نتايج حاصل از اين آزمايش نشان‌دهنده‌ي عملكرد لرزه‌يي مطلوب سيستم، جذب انرژي مناسب، و رفتار پايدار در نواحي غير خطي است. تحليل اجزاي محدود نمونه‌ي آزمايشگاهي انجام و نتايج آن ارايه شده است و انطباق خوبي بين نتايج تحليلي و آزمايشگاهي مشاهده شد.

Recent research has demonstrated that thin steel plates have good performance under shear loading, and due to that property, they have been used in some lateral resistant systems such as steel plate shear walls. In the present study, it is intended to employ shear panels for seismic performance improvement of concentrically braced frames. Hence, a combined system is developed and its non-linear behavior has been analytically and experimentally investigated. For experimental study, a scaled one-story steel shear panel model, with hinge type connections of boundary elements at four corners, is selected. Two rows of bolts with a diameter of 10 mm are used for connections of an infill steel plate to the surrounding frame. The boundary elements of the specimen are similar, while the infill steel plate thickness is a 0.9 mm specimen, consisting of the standard profile double section UNP100 as boundary elements. The specimen depth and width are equal to 400 mm. The specimen is subjected to quasi-static cyclic loading along its diagonal axes. The ultimate shear strength of the system, based on test results, is obtained as 8.2 tons. Experimental results show that using a steel shear panel in concentrically braced systems can improve the hysteretic curve of the system and dissipate a large amount of input energy in the nonlinear range. Finite element analysis of the laboratory specimen has been carried out, and in the analysis, a multi-linear kinematic hardening model is assigned to the boundary element and infill plate. It is obtained that the used analytical method has been successful in estimating the actual shear capacity of the system and the initial stiffness of the system in comparison with experimental results. It is found that the simulation outcomes show good agreement with experimental results. A fundamental point in the designing of this kind of system is that the buckling capacity of the system should be more than the capacity of the steel shear panels, to ensure that the panel is entered into the non-linear range without any buckling in the braced members. To achieve this goal, in the design of the steel shear panel and braced members, some equations have been proposed.