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Steel shear walls has been noticed against wind and earthquake lateral loads about high buildings in the last three decades. This modern phenomenon is growing rapidly worldwide so that system have been employed highly in construction of new buildings and seismic upgrading of existing buildings in some countries such as USA and JAPAN. That is a very simple system from viewpoint of implementing and there isn’t particular complexity. High strength and ductility are main advantages of these systems. Current paper has investigated comparatively behavior of steel shear walls made of smooth and corrugated sheets. Also the paper has assessed push-over curves and cyclic binding. According to this result of the research, corrugated steel shear walls have lower ductility than smooth shear walls. The research also founded that despite the high strength of corrugated sheets in low displacement, behavior of flat shear walls is more stable than corrugated shear walls. On the other hand flat steel shear walls attract energy more than corrugated shear walls. Therefore using of flat shear walls is recommended in high seismic regions. In this research, 18 samples of flat steel shear walls and corrugated shear walls were modulated. In all models, panels height were 3 m and panels span were 3, 4 and 5 m. the thickness of sheets in the samples were 3, 4 and 5mm. According to results of the research: 1- Corrugated sheets are unstable and unpredictable in high thinness. In the low displacements occurs a mutation state, so it distinguishes the corrugated and flat shear walls behavior. 2- At low displacement, a corrugated sheet bears greater load than a flat sheet. 3- In a constant thickness for thinner corrugated sheets is increased the mutation rate and its behavior becomes more non-uniform. 4- Despite of the fact, pynchyng phenomenon appears in all samples, but all samples behavior is stable and significant energy attraction is observed.

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Steel plate shear walls are very effective lateral load resisting systems which have high lateral stiffness and high ductility capacity at the same time. Although there are valuable experimental data available for such systems, most of the current seismic codes (including Iran’s Standard NO. 2800) provide none or limited design provisions for such structural systems. One of the important seismic performance parameters of the structures is “over-strength factor” which is implicitly or explicitly part of seismic design base shear formulation. Most of the available data on this factor are obtained from experimental research and therefore results are limited to low-rise structures and/or with reduced scaled structures/specimens. The main objective in this research is to assess the over-strength factor for the steel plate shear walls. A closed-form-solution is proposed for obtaining this factor based on a plate-frame interaction. This formulation is on the basis of the assumption that steel plate yields first and then the frame undergoes into the inelastic range. Therefore, an important factor that controls the amount of overstrength in an steel plate shear wall panel is the ratio of the steel plate yield displacement to the that of the steel frame. The lower this ratio is the higher the overstrength factor would be. The results of four experiments from four different universities accross the world were considered. The results also include the geometric and material properties of the specimens as well as their hystresis behaviors under cyclic loading. From the hystresis loops one can obtain experimental overstrength factors. It was found that the over-strength factors obtained by this proposed method are in line with available experimental results obtained from these four tests. It was also found that as the steel plate thickness decreases, the overstrength factor increases. Also, as yield stress of the steel plare decreases, the overstrength factor increases. In other words, the softer the steel plate /panel becomes, the better the chance of the redistribuition of internal forces would be and therefore the higher the overstrength factor would become. Two sets of results and/or comparisons are made in this study. First for the purpose of vrification of the proposed closed form solution, one of the test specimens were extended and it was shown that for the certain condition of that the test the proposed formulation matched the experimental results however if the plate thickness were to increase the overstrength factor would drastically decreases. The second set of results were for steel plate/panels with real sizes and not small lab sizes. It was shown that for such moderate and realistic steel panel sizes and thicknesses the overstrength factor comes out to be about 1.3. In addition, an square like panel has the highest overstrength factor compared to a rectangle ones.

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In recent years using steel plate shear wall system, because of its advantages in comparison with other earthquake resistant systems, has been a matter of attention. Some of its advantages relative to other systems include abundance advantage, high ductility, good hysteretic behavior and energy absorption capacity, high stiffness and economic advantages. Regarding that in Iran there is high seismicity risk and the need to strengthen old and unsafe urban textures and buildings, using this system as a lateral load resistant system seems appropriate and economical. In the present research strengthening of x-braced steel frames with steel plate shear walls is evaluated. Addition of bracing to unbraced frame spans, substituting braces with thin steel shear wall panels and adding thin steel shear wall panels to unbraced spans which do not have architectural requirements are considered as retrofitting strategies. The focus is on the methods in which retrofitting is only done by adding steel plate shear wall elements to braced frames. Some of these methods have many economic and practical advantages. Others are only proper for some special cases. In this study a number of x-braced steel frames designed by the first edition of Iranian code of practice for seismic resistant design of buildings (Iranian Standard No. 2800) are taken as basic frames which need to be retrofitted. These basic frames are retrofitted by adding steel panels with different methods. Then nonlinear static analysis (pushover analysis) with displacement control pattern has been done on both basic and retrofitted finite element frame models and the capacity curves (diagram of story displacements against base shear) of basic frames and retrofitted frames are compared. Considering the results of the pushover analysis of models in which seismic retrofitting is done by replacing x-bracing earthquake resistant system with steel plate shear walls and the results of other methods of strengthening, it is seen that seismic behavior of retrofitted frames is more desirable in terms of overstrength factor (Ω) and overall ductility of structure ( ). The failure and fracture mode in most of the medium-rise frames was ductile but in the short-rise frames the fracture was brittle. Thus, replacing the braces in short-rise structure with thin steel shear walls seems irrational and unjustified economically. But it is to be mentioned that strengthening and increasing the moment of inertia of the adjacent columns of steel shear wall panels in structures with brittle fracture mode could result the change from brittle to ductile fracture. The results of this research show that in the case of steel braced frames with regard to some scientific, technical and practical points; replacing concentric steel bracing earthquake resistant system by steel plate shear walls can be used as a suitable method for retrofitting a wide range of existing steel structures in Iran.

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Semi-supported steel shear walls (SSSW) are a new lateral resisting system whose plates do not have any direct connection to the main columns of structure. Instead, they are connected to secondary columns which do not carry the gravity loads. The applied lateral loads may create overturning moment on the middle storeys. The ultimate shear capacity of the SSSWs in presence of the overturning moment has been reasonably determined with an analytical procedure. It was finalized with some applicable interaction curves between the ultimate shear capacity and the overturning moment which can be used for analysis and design of this system. In addition, some experimental studies have been conducted to find an insight for the cyclic behavior of this system. As the elastic buckling of wall plate always occurs at the low levels of lateral loads, the system stays in a relatively large region of elastic post-buckling. In this region, the geometrical nonlinearity with linear material behavior appear in the wall plate. Thus, the storey shear force has a linear variation versus the lateral displacement until the first point of wall plate is yielded. Perhaps solution of the Von-karman plate equations is the best approach to find an analytical vision for the elastic stiffness of the SSSWs. These equations are described with two coupled nonlinear fourth order differential equations. The mentioned equations have been widely solved for many plates which are under combinations of different in-plane and out of plane loads and various boundary conditions and imperfections. In this study, the Galerkin method was employed in a semi analytical procedure to solve the Von-karman plate equations for the wall plate of SSSW system in a middle storey. This solution leads to achieve the displacement field of the SSSWs at the different levels of lateral loads until the first point of the wall plate is yielded. Thus, the linear variations of the in-plane displacement versus the lateral load will be obtained. Since the ultimate capacity has been previously measured, then an ideal elasto-plastic curve can be obtained for this system. The wall plate is supposed as a thin plate whose parallel edges have two different boundary conditions: two simply supported and two stiffened free edges where the wall plate is connected to the storeys beams and the secondary columns respectively. A sine monomial is considered as the deflection function which is satisfied the boundary conditions. Then, an algorithm is analytically developed to find the out of plane deflection of plate and the two-dimensional elasticity is used to determine the in-plane displacement of plate. The obtained results are compared with those of FE analysis and the suggested algorithm can be programmed in usual computers. The results show that some parameters such as the wall plate dimensions, the geometric properties of secondary columns (i.e. cross sectional area, moments of inertia), the storey shear force and yield stress of wall plate effect on the end point of elastic post-buckling. But, the slope of this region is independent from the variation of overturning moment and section of secondary columns.