The lateral-torsional buckling of beam is a disadvantage for connections with reduced beam section (RBS). One effective method for preventing such buckling is to reduce web section (RWS) instead of flange. This, not only eliminates the disadvantage of RBS, but also, provides better behavior and more ductility. This paper investigates the effect of longitudinal and transverse web/flange slits on the behavior of Bolted steel moment frames. The investigated frames include: frame with full beam section and frames with beams reduced by: radial cut in flange, longitudinal slits in flange, transverse slits in flange, longitudinal slits in web, transverse slits in web, mixed web slits, and, cruciform web slits. These one-story one-bay frames are analyzed using nonlinear finite-elements method with shell elements of type S4R and solid elements of type C3D8R in ABAQUS. The quasi-static cyclic loading according to Supplemental Access Control protocol is applied to the frames. The results show that by using RWS beams, the location of plastic hinge can move from column face to an appropriate distance at the reduction region. According to the results, the maximum rupture index (RI) occurs in frame with full (not reduced) section; while, the minimum RI belongs to RWS frame with longitudinal web slits. The larger the RI, the greater is the probability of rupture at low drifts. The hysteresis curves of frames show that the strength of frames with longitudinal or transverse flange slits decreases at final step of loading, i.e. at the last two cycles with greatest rotation angles. The frame with longitudinal web slits with 31.8% more load-carrying capacity and 30.9% more energy dissipation, shows better performance compared to the other RWS or RBS frames.

Construction of welded moment resisting connection is common. These connections have high potential for brittle failure of welds if quality of welding is not controlled. In this research new Bolted bracket connection similar to Kaiser Bolted bracket connection is introduced. Kaiser connection has invention patent so construction society can’t utilize them without authority. Proposed connection of this paper can be manufactured by both casting and welding methods and can eliminate patent problems. In this evaluation connection performance, pretention force of bolts, height of bracket, number of bolts and length of bracket have been evaluated. In modeling of connection in order to accuracy of results between different connected area and bolts faces contact elements were created. The standard cyclic history was selected for loading of specimens. The results shows that proposed connection can be accepted by connection code for using in special moment resisting frames from both ductility and strength aspects. Findings are extended as hysteresis curves, released energy of connection, rupture index indicators and slip of bolts.

Progressive Collaps is a phenomenon in which a partial damage or local breakdown or initial local failure from one element to another causes a collapse in the whole structure or a large part of the structure. Due to the fact that the behavior of structures in the progressive failure can be related to various factors, such as how the loads are transferred to the nodes, the type of connections and their behavior can be very effective in the progressive Collaps of the structure.Therefore, the study of the effect of the type of connection in the progressive Collaps of the structures can demonstrate the performance of the Resistant systems of the structural steel well. To investigate this issue, steel structures, structures with a number of floors 5, 8, 10, 15 with a folding backrest system whose fittings are tight and fitted with a simple frame system whose joints are articulated, loaded and designed based on SAP2000 software. By analyzing the time history of the models, it is determined that the number of seismic responses, including the amount of lateral displacement of the classes, the base cut, the internal force of the columns, and the expansion of the failure in the structures in the use of the bending frame and the bracing frame relative to Different. It should be noted that the axial, shear and flexural forces of the elements in the frames are more than the frames, and based on the position of the column removal, it is different. Therefore, it can be said that the values of internal forces in the bending frame are more than the bracing and the amount of vertical displacement and less than the bracing frame.

The goal of multi-frame Super Resolution (SR) is to fuse multiple Low Resolution (LR) images to produce one High Resolution (HR) image. The major challenge of classic SR approaches is accurate motion estimation between the frames. To handle this challenge, fuzzy motion estimation method has been proposed that replaces value of each pixel using the weighted averaging all its neighboring pixels in all LR images which carries the degree of similarity between image blocks centered on two pixels. Since in case of rotation between LR images, comparing the gray level of blocks around the pixels is not a suitable criterion for calculating weight, so, magnitude of Zernike moments (ZM) has been used as a rotation invariant feature. Due to the lower sensitivity of Pseudo Zernike moments (PZM) to noise and the higher discrimination capability of it for the same order compared to ZM, in this paper, we propose a new method based on magnitude of PZM of the blocks as a rotation invariant descriptor for representation of pixels in weight calculation. Experimental results on several image sequences show that the performance of the proposed algorithm is better than the existing and new techniques from the aspect of PSNR and visual image quality.

In this paper, steel ordinary moment resisting frame buildings designed according to the Iranian Earthquake Code (Standard No.2800, 2nd edition) are evaluated based on seismic retrofitting provision for existing buildings. Also, their seismic performance is investigated in the range of both linear and non-linear behaviors. At first, several common samples of these systems were designed through 2800 code. So, critical frame of these samples was controlled using the seismic retrofitting provision in base upgrading level through the several detailed numerical analyses (non-linear static, linear dynamic spectrum and time history). Based on the obtained results, bending performance of all members in all structures is controlled by deformation and with linear dynamic time history analysis using the record of happened earthquakes in Iran such as Bam, do not need to be strengthened. The shearing low-height structures showed a reasonable performance in the range of non-linear behavior. However the flexural structures (6 and 8-storeyed) with non-linear static procedure and all of structures with linear dynamic spectrum method should be improved.

Steel moment system and steel moment with centrically braces are two common systems. Many of regulations related to this structures explained in details to design structures against earthquake loads but theydidn’t mention methods about dynamic load such as blast or car crash. However, the mentioned parameters may cause key member fracture such as column that result total or partial damage. Therefore, investigation about these structures seems necessary. This paper presents a numerical study of 20 story steel building with two different lateral systems and two column removal scenarios using Abaqus. Three dimensional modeling, using the finite element method was developed and investigated to understand the progressive collapse of 20 story buildings with composite steel frames. Numerical result verified with experimental results. The response of the building was studied in detail and results are recommended to mitigate progressive collapse in future designs. The results of this study show that corner column case removal is more critical than side case removal from view point of increasing axial force and moment. Also the results indicated that behavior of different structures systems against progressive collapse is NOT remarkable. To avoid potential progressive collapse, it suggests that the columns were designed and controlled for double of service loads.

Following the Northridge earthquake of 1994, a significant number of steel moment resisting structural systems were damaged. Several studies have been conducted to improve the seismic performance of steel structures and specially their beam-to-column connections. One of the proposed connections for special moment-resisting frames included in AISC-358 is Kaiser Bolted bracket moment connection, briefly named, KBB. The brackets in these connections are precast steel elements. In this study, the seismic behavior of moment connection KBB has been examined under standard loading history and near-fault loading history according to ATC and FEMA codes. The results show that KBB connection has acceptable seismic performance except for deep beams. In deep beams a high prying force may occurs in upper rows of the bolts. the main reason for such phenomenon is rigidity of the bracket. Moreover use of Tapered Wedge Shims reduces pre-tensioned force in bolts and increases pinch in hysteresis curve of specimens.

Finite element (FE) analyses were performed to explore the prying influence on moment–rotation behaviour and to locate yielding zones of top- and seat-angle connections in author’s past research studies. The results of those FE analyses with experimental failure strategies of the connections were used to develop failure mechanisms of top- and seat-angle connections in the present study.Then a formulation was developed based on three simple failure mechanisms considering bending and shear deformations, effects of prying action on the top angle and stiffness of the tension bolts to estimate rationally the ultimate moment Mu of the connection, which is a vital parameter of the proposed four-parameter power model.Applicability of the proposed formulation is assessed by comparing moment-rotation (M- qr) curves and ultimate moment capacities with those measured by experiments and estimated by FE analyses and three-parameter power model. This study shows that proposed formulation and Kishi–Chen’s method both achieved close approximation driving M-qr curves of all given connections except a few cases of Kishi–Chen model, and Mu estimated by the proposed formulation is more rational than that predicted by Kishi–Chen’s method.

Evaluating the moment-rotation behavior of Bolted connections by finite element method is very intensive task in terms of computational cost. This study proposes an efficient neural system to predict the moment-rotation behavior of the connections. The neural system is called self-organizing back propagation (SOBP) networks. The SOBP includes two processing units: classification and approximation. In the classification unit, all the training data are divided into some classes by a self-organizing map network. In the approximation unit, a set of back propagation networks are employed to achieve the approximation task. The numerical results demonstrate the computational advantages of the SOBP.

In a core-wall structure with buckling restrained braces (BRB) outrigger, locations of the plastic hinges are influenced by the outrigger action. Therefore, the designer should consider the issue and use suitable details in the plastic hinge area. The essential questions that arise here are the plastic hinge location and the design moment demand used for design of this kind of structure. In this paper, responses of the core-wall buildings with BRB outrigger designed by using the traditional response spectrum analysis (RSA) procedure, are assessed by implementing the nonlinear time history analysis (NLTHA). The result demonstrates that the plasticity can extend over anywhere within the core-walls specially, at the base, and above or below the outrigger levels. Formation of three plastic hinges in the core-wall is recognized suitable for the system.  To control the plasticity extension in the core-wall, it is recommended that a new modal combination method be applied to calculate the moment strength of the three plastic hinges over the height. A capacity design concept is used to design other regions of the core-wall where the plasticity does not extend to. The proposed procedure improves behavior of the system by restricting the plasticity extension to the predefined plastic hinge regions.