بررسي اثر مقاوم سازي ديوار برشي فولادي بازشودار با الياف FRP به روش عددي

Effect of FRP Reinforcement in the Steel Shear Wall with Opening via Numerical Methods

سيستم ديوار برشي فولادي كه در دهه هاي اخير به لحاظ مطالعات و به كارگيري مورد توجه محققين و صنعتگران قرار گرفته است، به عنوان يك سيستم مقاوم در برابر بارهاي لرزه اي شناخته مي شود. عملكرد ديوار برشي فولادي در سازه ها همانند ديوار برشي بتني مي باشد و به كارگيري سيستم ديوار برشي فولادي در سالهاي اخير نشاندهنده رفتار بسيار مناسب اين سيستم در سازه ها به خصوص در استهلاك انرژي لرزه-اي و كنترل تغييرشكلها مي باشد. همچنين با توجه به آن كه از ديرباز وجود بازشوها در ديوارهاي برشي به جهت ايجاد تمركز تنشها و ديگر ضعفها مورد توجه و بررسي بوده است، در اين تحقيق، 83 مدل ديوار برشي فولادي بازشودار در قاب فولادي با انواع آرايش سخت كننده هاي FRP* با استفاده از نرم افزار ABAQUS تحت تحليل غيرخطي اجزا محدود، مدلسازي و مورد بررسي قرار گرفته است. نتايج نشان مي-دهد، با در نظر گرفتن انواع آرايش سخت كننده ها، توزيع تنش در ورق و المان هاي مرزي بسيار يكنواخت تر و تنشهاي پيرامون بازشو در ورق كاهش مي يابد. همچنين، با توجه به وجود كمانشهاي بحراني در لبه هاي بازشو، سخت كننده هاي افقي- قايم توام، در كنترل كمانش خارج از صفحه ورق تاثير به سزايي داشته و سخت كننده هاي ضربدري به لحاظ بازدهي مصالح بيشترين تاثير در افزايش ظرفيت برشي، سختي و جذب انرژي را دارند.

Steel shear wall system in terms of research and development in recent decades has been considered by researchers and industrialists, as a resisting system against seismic loads. The steel shear wall performance in structures is like concrete shear walls but the main feature of this system is that; it is more affordable and also more accurate in implementing. Therefore, the use of steel shear wall systems in recent years has shown very suitable behavior of the system in structures, especially for seismic energy dissipation as well as deformation control. In the steel shear walls, firstly, by the buckling of the steel plate within the allowable limits and then formation of the diagonal tension, this generated post-buckling strength does play a role in improving the structural behavior. As a result, it can be concluded that monitoring and controlling the out-of-plane buckling of the steel shear walls would lead to optimizing the use of this system. In this regard, steel shear walls are often stiffened and implemented by utilizing steel straps. On the other hand, with regard to the opening sin steel shear walls, the main concern has been the stress concentration generated in the vicinity of the opening and thus, it can be stated, the use of FRP material sand FRP stiffeners placement on obtaining the perfect solution for controlling the steel plate buckling and other structural weaknesses used by the presence of the openings, is a very good remedy. To this end, in this study, the behavior of steel shear walls with openings reinforced with FRP fibers has been scrutinized. Accordingly, 83 models of steel shear walls with openings are generated and analyzed by employing the well-known ABAQUS software via a nonlinear finite element analysis. The results show that, considering different arrangements of the FRP stiffeners, a much more uniform distribution of the stresses in the steel plate as well as the boundary elements would be achieved and the stresses near the opening decreases. Moreover, according to the critical buckling occurs at the edges of the opening, the use of combined horizontal- vertical stiffeners, have an important role in controlling the out-of-plane buckling of the plate while the diagonal stiffeners have proved to be the best arrangement in increasing the structure shear capacity, stiffness and energy absorption. Thus, the effect of changes in dimensions of the openings for a fixed area of the openings as a percentage of the steel shear wall area on parameters such as the shear capacity, the out-of-plane buckling, energy absorption and the in-plane stresses have been studied. Due to the obtained results, the influence of the height is more than the width of the openings. Furthermore, the shear force correction factor for the opening are equals to 20 percent of wall area, is variable from 59% to 88%, depending on the shape of the opening. Finally, the behavior factor for the steel shear wall with the opening and reinforced with FRP, is obtained 15 for average of 20 random samples via the Young’s method.