@article{ author = {cheraghi, abdullah and zahrai, seyed mehdi}, title = {Performance Evaluation of Yielding Pipe in Pipe Damper by Using Incremental Dynamic Analysis}, abstract ={Using of passive dampers is one of the common method to improve dynamic characteristics of structures and reduce the earthquake force. The Philosophy of such dampers is using of interchangeable energy absorbing devices to focus damage on them in the hope that reducing structural damage in the other main members. Suitable seismic performance, relatively low price and ease in design and implementation are their benefits, but invariant performance parameters proportional to the type and amount of input energy decreases their efficiency. In this study, at first a new multi stage passive damper with variable stiffness, strength and energy absorption capacity is introduced and its performance in three 5, 10 and 15 floors frames is evaluated by incremental nonlinear dynamic analysis using the SAP2000 software. Results indicate that despite of differences in dynamic parameters of selected seismic records such as duration and frequency content, structural performance has been significantly improved which proved new damper effectiveness on improving the seismic performance of structures. Besides, results show the structural performance levels improvement and increasing its energy absorption capacity. The first mode spectral acceleration of moment frame structures reached to 4.75g, 4.53g and 3.36g respectively for 5, 10 and 15 story frames which confirms the downtrend by increasing the number of stories. Moreover, the related amounts in the structures equipped by new damper, obtained 5.95g, 4.98g and 3.93g respectively. Comparing the median values, revealed significant differences in the behavior of moment frames and frame equipped by proposed damper such that increasing the spectral acceleration and relative displacement causes horizontal part in the moment frame IDA graphs due to the lack of lateral stiffness. But, in all three damper structures, performance enhancement and relative displacement decrement is visible and even at the end of the IDA graphs, there are remarkable capacity to cope with lateral forces. According to the results, the proposed damper despite its simplicity, applicability and relatively low cost, demonstrates good performance in reducing the input energy and seismic vibrations of structures.}, Keywords = {Multi stage control system, Pipe in pipe damper, Structural capacity, Incremental dynamic analysis}, volume = {13}, Number = {25}, pages = {5-15}, publisher = {Iranian Society of Steel Structures }, url = {http://journalisss.ir/article-1-142-en.html}, eprint = {http://journalisss.ir/article-1-142-en.pdf}, journal = {Journal of Structure & Steel}, issn = {1735-515X}, eissn = {1735-515X}, year = {2019} } @article{ author = {}, title = {Multi Level Estimation of Reduction Factor in Eccentric Braced Frame Systems with Vertical Link}, abstract ={The use of vertical links in eccentric braced frames, in addition to special system privileges, is one of the best methods of passive structural control. Past studies regarding the reduction factor of aforementioned systems are valuable but limited. The purpose of this study was to understand the mechanism of failure in frames equipped with vertical links, during which, while defining and elaborating the estimation steps of demand and capacity reduction factors, these two parameters have been evaluated for 4 and 8-story building frames with the aforementioned systems. The distinction between the present study and other similar studies of reduction factor estimation is multilevel assessment based on seismic demand and frame capacity. Based on the results, the system has high ductility, so that the use of design reduction factor up to 8 will also provide reasonable seismic reliability for frame buildings under the medium and high earthquake intensities.  }, Keywords = {Eccentric braced frames, vertical link, demand reduction factor, IDA}, volume = {13}, Number = {25}, pages = {17-33}, publisher = {Iranian Society of Steel Structures }, url = {http://journalisss.ir/article-1-208-en.html}, eprint = {http://journalisss.ir/article-1-208-en.pdf}, journal = {Journal of Structure & Steel}, issn = {1735-515X}, eissn = {1735-515X}, year = {2019} } @article{ author = {Ghouhestani, Soleiman and Shiri, Mehr}, title = {Study the effect of opening position on shear buckling strength of perforated steel plate girder with delta stiffeners under shear force}, abstract ={Nowadays, the use of plate girder in different kinds of structures has been increased. One of these is plate girder with delta stiffener. Investigations have shown that the bending and shearing behavior of plate girder with delta stiffener are better than usual plate girder with uniform sections. Preparing web openings to make space for service, inspection and passing the big pipes is unavoidable in plate girders. In this study, employing ANSYS v.12 software, the modeling of hole in the web of plate girder was done and the effective parameters on shear buckling strength of perforated steel plate girder was considered to study the structural behavior and optimum range for Preparation of web hole and the best form of ordinary kinds of hole. The results show that, the best web performance location is between 0.30 until 0.35 of length, optimum of effective height parameter (ratio of hole diameter to distance of stiffener connection from intersection at web to the bottom flange) is between 0.26 until 0.27, and there is a linear behavior between shear buckling strength versus changes in hole diameter of opening which is presented by an equation. The comparison between different opening shape with equal surface (square, circle and triangle) indicates that the square opening has the priority in buckling shear strength in comparison with other shapes.}, Keywords = {Plate Girder, Delta Stiffener, Perforated, Shear Buckling}, volume = {13}, Number = {25}, pages = {35-44}, publisher = {Iranian Society of Steel Structures }, url = {http://journalisss.ir/article-1-237-en.html}, eprint = {http://journalisss.ir/article-1-237-en.pdf}, journal = {Journal of Structure & Steel}, issn = {1735-515X}, eissn = {1735-515X}, year = {2019} } @article{ author = {Babaei, Mehdi and Moradi, Mostaf}, title = {Multi-Objective Optimization of Semi-Active Fluid Viscous Dampers using Imperialistic Competitive Algorithm}, abstract ={Semi-active control systems and semi-active fluid viscous dampers as a subset of these systems, have shown their ability to reduce seismic responses of building, one of the most important advantages of these dampers is ability of adjusting with structures behavior to overcome the earthquake forces. In this thesis, multi-objective optimization of operation of semi-active fluid viscous dampers in reduction of seismic responses of buildings subjected to horizontal components of earthquake accelerations is studied. The optimum number and position of dampers are considered as decision variables and structural responses such as maximum story acceleration, maximum last story displacement and maximum story drift are considered as objective functions, should be minimized. The optimal solutions show that although viscous dampers reduce the structural responses, however, a certain configuration of dampers in specific locations of the structure could be efficient for reduction of the structural responses.}, Keywords = {Semi-active control, Fluid viscous damper, Multi-objective optimization, Imperialistic competitive algorithm}, volume = {13}, Number = {25}, pages = {45-55}, publisher = {Iranian Society of Steel Structures }, url = {http://journalisss.ir/article-1-125-en.html}, eprint = {http://journalisss.ir/article-1-125-en.pdf}, journal = {Journal of Structure & Steel}, issn = {1735-515X}, eissn = {1735-515X}, year = {2019} } @article{ author = {Beiraghi, Hami}, title = {Seismic response of steel structures with buckling restrained braces with and without viscous damper under near and far fault earthquakes}, abstract ={The appreciation of buckling restrained brace systems has increased over the past two decades. The relatively high energy losses and optimal ductility are the characteristics of this system and the l displacement control as well as the residual displacement is challenging issues under the earthquake. In this paper, the behavior of simple frame structures with buckling restrained braces with and without viscous dampers in intermediate and high rise buildings under the influence of   near fault and far fault records was investigated. Initially, the structures were analyzed using a spectral dynamical analysis method and valid regulations. Then nonlinear model of structures was developed in PERFORM-3D software and nonlinear time history analysis was performed. The response of the structures was examined and compared. The results show that the inter-story relative displacement in the structure with buckling restrained braces and fluid damper under far fault earthquakes compared to without damper case decreases by about 30%, with the corresponding value under the near-earthquake of about 15%. The maximum resistive force of the liquid damper appears at the moment of the most inter story relative velocity, and this is evident in the buckling restrained brace in the most inter story relative displacement. Due to the phase of relative inter story displacement and relative inter story velocity, the use of a hybrid system can lead to better control of structural responses.}, Keywords = {Frame, viscous fluid damper, buckling restrained braces earthquake, residual inter-story drift, time history, analysis}, volume = {13}, Number = {25}, pages = {57-67}, publisher = {Iranian Society of Steel Structures }, url = {http://journalisss.ir/article-1-217-en.html}, eprint = {http://journalisss.ir/article-1-217-en.pdf}, journal = {Journal of Structure & Steel}, issn = {1735-515X}, eissn = {1735-515X}, year = {2019} } @article{ author = {izadinia, mohsen and Molavi, Reza and Shahidi, Alirez}, title = {Cyclic Behavior of Beam-to-Column Connection with Yielding Steel Rods Damper in Shear}, abstract ={The present study tries to examine the seismic behavior of a new type of beam-column connection having yielding damper with circular placement pattern. The main purpose of the proposed system is to use yielding dampers in a space as high as the beam depth in order to occupy much lesser space, and not to reduce the useful height of the story  in the beam-column connection, so that the inelastic deformations from cyclic loading is restricted to the dampers. Three samples were made in the laboratory and were loaded up to 0.05 radian rotation under the cyclic loading. In order to evaluate the numerical modeling techniques and analyses in predicting the cyclic behavior of the proposed connections, finite element models of  laboratory samples were made and were analyzed based on corresponding  loading pattern. Based on the numerical and experimental results, inelastic deformations  were concentrated  in the dampers for all proposed connections and  the beam and the column remained within the elastic range. It is also possible to achieve a higher resistance that of the plastic moment of the beam in the proposed connection with a suitable design.}, Keywords = {Beam-to-column connection , damper , Cyclic behavior}, volume = {13}, Number = {25}, pages = {69-81}, publisher = {Iranian Society of Steel Structures }, url = {http://journalisss.ir/article-1-226-en.html}, eprint = {http://journalisss.ir/article-1-226-en.pdf}, journal = {Journal of Structure & Steel}, issn = {1735-515X}, eissn = {1735-515X}, year = {2019} } @article{ author = {Haghollahi, Abbas and Safavi, Aliasghar}, title = {Non-sway In-plane Buckling of Columns in Gable Frames with Virtual Work and Finite Differences Methods}, abstract ={In this paper, non -sway flexural buckling for non-prismatic columns is analyzed. The studied structures are one-bay gable frames, which are evaluated for in-plane buckling, and their two bases are hinged or rigid using virtual work and finite difference methods. First, the length of the column is divided into "n" parts. Then the deformation differential equations of these parts are converted into finite difference forms. Thus "n-1" linear equations with "n" variables are obtained. These variables are the lateral displacements of the specified points on the length of the column. Now, an equation is required to complete the system of linear equations.  It can be obtained by employing the virtual work method. The equations’ system corresponds to a matrix equation in which the coefficient matrix is a square matrix. By letting the determinant of this matrix be equal to zero, an n-degree linear equation is produced. The buckling load is the minimum root of this equation. The results are shown in dimensionless charts. To verify the results, some examples are solved with the introduced method and other methods. The comparison shows that the buckling load can be easily calculated using the introduced method with a good accuracy.  }, Keywords = {Gable frames, Non-sway buckling, Non-prismatic columns, Finite differences method, Virtual work method}, volume = {13}, Number = {25}, pages = {83-99}, publisher = {Iranian Society of Steel Structures }, url = {http://journalisss.ir/article-1-243-en.html}, eprint = {http://journalisss.ir/article-1-243-en.pdf}, journal = {Journal of Structure & Steel}, issn = {1735-515X}, eissn = {1735-515X}, year = {2019} } @article{ author = {Bayat, khadije and Shekastehband, Behz}, title = {Investigation of strips of slit damper and introduction dual T shape slit damper in seismic performance of beam to column connection}, abstract ={It is recommended to use Slit dampers to prevent brittle failure in the connections and also to reduce post-earthquake damage. These dampers have their own strips that the strips created energy dissipative and  absorbing and prevent the destruction of the main members of the structure. According to studies on the effect of strips on energy dissipation, the method of placing the strips has investigated in an angle of 45 degrees and in combination of horizontal and vertical. Also, due to the fact that this damper is located in a semi-rigid connection, a dual T-shaped damper is proposed for short-beam to rigid connection. All models were analyzed by Abaqus software under cyclic loading. In the results of the hysteresis diagram, the maximom moment of damper with an angled strip is about 2 times greater than the maximum moment which is proposed by Oh and his colleagues (2009),  and, the maximom moment of damper with the combined strip is about 1.3 times greater, and more energy dissipation observed. Also, in the case of  damper of rigid connection, the energy dissipation was tangible.  }, Keywords = {Rigid connection, Slit damper, Angled strip, Combination strip, dual T shape slit}, volume = {13}, Number = {25}, pages = {101-109}, publisher = {Iranian Society of Steel Structures }, url = {http://journalisss.ir/article-1-235-en.html}, eprint = {http://journalisss.ir/article-1-235-en.pdf}, journal = {Journal of Structure & Steel}, issn = {1735-515X}, eissn = {1735-515X}, year = {2019} } @article{ author = {Siahpolo, Navi}, title = {High strength steel; Endplate connection; moment capacity; connection rotation}, abstract ={A beam-to-column connection has a significant role in the behavior of steel structure under the effect of verity loads. Rigid connection in steel moment frame has a special role in the behavior of these structures. Moreover, the fire resistance of these connections can be important. Among these parameters, steel material used in the connection is important and its investigation seems necessary. In this article, the behavior of 9 steel moment end-plate connections under the effect of various degrees of temperatures was studied using finite element methods through ABAQUS software. The connections have been designed, modeled and analyzed using three types of steel materials. The models verified by the use of an experimental model through elastic and plastic amplitudes up to collapse and during numerical results, the effect of large deformation in the nonlinear region has also been considered. The results of this study show that using of the stiffeners improves connection capacity and performance. The results of this study show that declined slope of moment capacity of connection with stiffener coming in all temperatures and is almost smooth and constant. However, it observed that the declined slope of moment capacity of connection with and without stiffener which designed with low strength steel was less than other connections during 800 to 900 degree which shows better performance of this connection.}, Keywords = {High strength steel, Endplate connection, moment capacity, connection rotation}, volume = {13}, Number = {26}, pages = {5-16}, publisher = {Iranian Society of Steel Structures }, url = {http://journalisss.ir/article-1-171-en.html}, eprint = {http://journalisss.ir/article-1-171-en.pdf}, journal = {Journal of Structure & Steel}, issn = {1735-515X}, eissn = {1735-515X}, year = {2019} } @article{ author = {jomemanzari, reza and ShahabianMoghaddam, Farz}, title = {A Survey of the Effect of Opening and Stiffener on Dynamic Response of FGM Plates under Blast Loads}, abstract ={The increasing risks resulted by blast loads in current broad and thin plates necessitate the studies and evaluation of these challenges. Practical and cost-effective solutions such as plates enforcement with stiffener are suggested due to high displacement of structure as a result of applied loads. Moreover, application issues and the possibility of developing opening in plates and thus their change of behavior are considered important issues, for which solutions are suggested in this study. Functionally graded plates (FGM) with a power distribution in the direction of thickness are suggested as a solution to this challenge. Accordingly, the present study assesses parameters related to plates with opening including kind, percentage and the position of opening, the mass amount of explosive material, and the parameters related to plates with stiffener including type, count, arrangement of stiffeners, boundary condition and also the joint effect of stiffener and opening using Abaqus Software. The results indicate that opening decreases the plate hardness which consequently increases the amount of displacement. Plate displacement constantly reduces as a result of increase in opening percentage and hence decrease in the surface on which load is applied. On the other hand, the rectangle shape of stiffener has a better performance due to higher moment of inertia and easier application compared to other shapes. By studying the joint effects of these factors, it can be suggested that developing opening and application of an appropriate stiffener can significantly reduce the amount of plate displacement compared to other types.  }, Keywords = {FGM Plate, Blast Load, Maximum Displacement, Opening, Stiffener.}, volume = {13}, Number = {26}, pages = {17-32}, publisher = {Iranian Society of Steel Structures }, url = {http://journalisss.ir/article-1-220-en.html}, eprint = {http://journalisss.ir/article-1-220-en.pdf}, journal = {Journal of Structure & Steel}, issn = {1735-515X}, eissn = {1735-515X}, year = {2019} } @article{ author = {Yeganehfar, Ali and Mehrparvar, Behnam and Gholamian, Hamidreza and Hadadshargh, Farz}, title = {Experimental assessment of seismic performance of panel zone in built-up box columns with corner welded joints}, abstract ={Application of box columns in steel moment frames is very common due to its bidirectional flexural resistance and also its shape which provides suitable surfaces for connection of beams in both directions. In Iran, because of limited availability of rectangular HSS sections, typically built-up box columns are applied which are fabricated by welding four steel plates to each other. According to seismic provisions, within a zone adjacent to the connection point of beam to column, flange and web plates of built-up box columns shall be joined by CJP groove welds. Because of the cost and difficulty of groove welding and concerns about achieving full penetration of weld in box sections, besides the common practice for fabrication of box sections in Iran by means of fillet-welded corner-outside joints, in this research seismic performance of moment connections between I-Shape beams and built-up box columns with corner welded joints was investigated experimentally. For this purpose, two specimens representative of special moment frames and two specimens representative of intermediate moment frames, all fabricated by built-up box columns using fillet welds or CJP groove welds, were designed and investigated. Investigation of the seismic performance of the specimens has been performed thru applying the cyclic load pattern presented in AISC341-16 standard. The results showed the capability of all 4 samples to satisfy the requirements for the required drift angle according to the specified load pattern.  }, Keywords = {Panel zone , Built-up box columns, corner welded joints, Seismic Performance}, volume = {13}, Number = {26}, pages = {33-40}, publisher = {Iranian Society of Steel Structures }, url = {http://journalisss.ir/article-1-267-en.html}, eprint = {http://journalisss.ir/article-1-267-en.pdf}, journal = {Journal of Structure & Steel}, issn = {1735-515X}, eissn = {1735-515X}, year = {2019} } @article{ author = {}, title = {Dynamic Effects of Belted Truss on the Seismic Behavior of Steel Tall Buildings with Braced Tube Skeleton}, abstract ={The aim of this research is to study the parameters of nonlinear dynamic behavior of steel tall buildings having a compound braced-tube resistant skeleton with belted trusses in higher levels. For this purpose, four 30-story study models have been designed in 3D. The first study model has a resistant skeleton without a belted truss. Yet, the remaining three structural models, each have a belted truss in higher levels with layouts of one, two and three stories, respectively. Numerical study results of this research are acquired according to a set of time-history nonlinear analyses on the mentioned study models. The chosen ensemble of three-component ground motions includes six highly powerful near-field records and one far-field record. Assessing study results reveal that applying belted trusses in tall braced-tube skeletons would lead in a remarkable increase in stiffness and a growth in the capability to absorb the earthquake’s kinetic energy. This issue also results in a large decrease in lateral displacement and dynamic drift of the structure and will therefore cause an increase in using the axial capacity of peripheral columns of the structure plan. Thus it becomes possible to introduce the application of resistant structures with belted trusses in structural skeletons of high-rise buildings, especially in areas with high seismicity as a suitable and efficient alternative plan compared to other structural systems.}, Keywords = {Tall Steel Building, Nonlinear Behavior, Braced Tube Skeleton, Belted Truss, Near-field Record}, volume = {13}, Number = {26}, pages = {41-58}, publisher = {Iranian Society of Steel Structures }, url = {http://journalisss.ir/article-1-169-en.html}, eprint = {http://journalisss.ir/article-1-169-en.pdf}, journal = {Journal of Structure & Steel}, issn = {1735-515X}, eissn = {1735-515X}, year = {2019} } @article{ author = {KhodaBandehLou, Ashkan and AligholizadKordlari, Vahi}, title = {Nonlinear Analysis of Seismic Response Considering the Effects of Site Characteristics and Frequency Content for Shallow and Deep Deposits}, abstract ={The studies have shown that the site characteristics such as soil layers properties and layer thickness can effect on the ground input motion and might change the acceleration frequency content and seismic duration. This research aims to study the effects of site characteristics on the ground response, and the response of the constructed buildings. In order to study the site effects on the ground seismic response, 14 far and near fault earthquake were considered and linear and nonlinear analysis on four different sites was performed. Additionally, one to four story buildings were modeled and the responses were analyzed using SAP 2000 software. Generally, the ground response related to the far and near fault earthquakes, the seismic input motion is amplified while passing through the earth layers and considering the acceleration, the maximum seismic motion increases. The smaller the maximum input acceleration of the seismic input of far fault earthquake, the less is the nonlinear and linear responses. For the cases with the larger near fault earthquake maximum ground acceleration, the analysis of the response, the response analysis using the linear equivalent approach shows that the soil layer of the input motion is amplified while passing through the soil layers. Comparing the graphs of the maximum acceleration versus the depth for the far fault earthquake, it can be inferred that the procedure cannot be generalized for the entire results of the far fault earthquakes. The maximum displacement in the depth increased with increasing the soil deposits thickness. For the similar stories buildings overlaid on the soil deposits, in both shallow and deep cases, the maximum displacement decreases with depth. On the other hand, the maximum obtained displacement in the linear and nonlinear times history analysis increases while increasing the number of building stories.  }, Keywords = {Nonlinear Analysis, Far and Near Fault Earthquake, Seismic Response, Soil Deposit, Plastic Hinge.}, volume = {13}, Number = {26}, pages = {59-75}, publisher = {Iranian Society of Steel Structures }, url = {http://journalisss.ir/article-1-228-en.html}, eprint = {http://journalisss.ir/article-1-228-en.pdf}, journal = {Journal of Structure & Steel}, issn = {1735-515X}, eissn = {1735-515X}, year = {2019} } @article{ author = {Safavi, Aliasghar and Haghollahi, Abbas}, title = {Characteristic Equation of Flexural Buckling of Columns in Two-bay Gable Frames for State of Free to Sway}, abstract ={In this paper flexural buckling load for tapered columns has been evaluated (in-plane buckling of frame). The studied issue is about two-bay frames. Their three bases are hinged, and sway is permitted. The analysis is based on the answer of the deformation differential equation of the column, imposing the boundary conditions at the tips of the columns, and the displacement compatibility equations at the nodes of the members. Therefore, a set of equations could be obtained. When the corresponding square matrix of the equations collection is available, the critical load will be calculated. The critical load is the minimum root of the characteristic equation. This equation is obtained by equating the determinate of that matrix to zero. The results of the analysis are compared with the other methods of other researchers in some examples. The comparison showed that the introduced method can calculate the critical load with a good accuracy. This method can be generalized for other frames made of tapered members.}, Keywords = {Flexural buckling, Gable frames, Tapered columns, deformation differential equation}, volume = {13}, Number = {26}, pages = {77-90}, publisher = {Iranian Society of Steel Structures }, url = {http://journalisss.ir/article-1-260-en.html}, eprint = {http://journalisss.ir/article-1-260-en.pdf}, journal = {Journal of Structure & Steel}, issn = {1735-515X}, eissn = {1735-515X}, year = {2019} } @article{ author = {HassaniSokhtesaraei, mohammad and Ghassemieh, Mehdi and Mirghaderi, Seyed Rasoul}, title = {Comparing Seismic Performance of WUF-W & RBS Moment Connections in Box-Section Columns Under SAC & ATC-24 Loading Protocols}, abstract ={The strength and deformation capacities of the structural elements are affected by the cumulative damage of that component. For this purpose the loading protocols used for investigating the performance of the connections should give an accurate estimation of the structural components capacities and yield appropriate simulation of the reality. It is essential to investigate the differences and features of the loading protocols. On the other hand, regarding the widespread use of the moment connections of I-shaped beam sections in the box-section columns, investigating the seismic performance of these moment connections is of vital importance. Meanwhile, the majority of code details for accepting moment connections are presented for H-shaped columns. For this purpose 12 types of RBS and WUF-W moment connections with box-section columns were designed and examined as analytical models in the study. The seismic behavior and difference in performance of these two types of moment connections were investigated and compared at the level of the relative displacement acceptance in the codes and also the collapse threshold under SAC and ATC-24 loading protocols. In continuation, while investigating the demand and applied energy, and the features and differences between the loading protocols, the conditions for strength loss at the collapse threshold of moment connections in the special moment resisting frame are also proposed.  }, Keywords = {SAC Loading, ATC-24, Box Section, RBS, WUF-W}, volume = {13}, Number = {26}, pages = {91-109}, publisher = {Iranian Society of Steel Structures }, url = {http://journalisss.ir/article-1-230-en.html}, eprint = {http://journalisss.ir/article-1-230-en.pdf}, journal = {Journal of Structure & Steel}, issn = {1735-515X}, eissn = {1735-515X}, year = {2019} }