Use of passive control systems causes reduction in seismic demand and prevents damage to the main components of the structure. yielding dampers are among the common tools used for dissipation of earthquake energy entering the structure. The main goal of the present research is introduction of a novel pseudo elliptical yielding damper for improvement of the seismic performance of the existing steel structures. Considering the impact of geometric parameters of the pseudo elliptical damper on its stiffness and strength, a precise numerical study was performed on the ratio of diameter to thickness and other dimensions of the damper in this research.  For evaluating the impact of proposed damper on the seismic performance of existing steel buildings, use was made of three benchmark structures with 3, 9 and 12 stories which were retrofitted by this type of dampers. Also, the nonlinear time history analysis has been performed using the near field and far filed accelerometers to evaluate the analyses results at different seismic states. The results of numerical analyses indicated the good performance of propose pseudo elliptical yielding damper in terms of dissipating the earthquake energy entering the structure and reduction in the seismic responses of retrofitted benchmark buildings by this type of dampers. It was found that on average, the maximum inter-story drift in the 3, 9 and 20 story benchmark buildings were reduced by 66, 69 and 67%, respectively.

Today, the use of energy-dissipating system such as yielding metal damper in structures can improve the seismic performance of structures. One of the characteristics of metal yielding dampers is the ability to dissipate high energy and increase the ductility of the structural system, which can improve the ductility and energy absorption characteristics of the metal frame equipped with braces and prevent the brace from buckling during an earthquake. The purpose of this research is introduce a new form of yielding dampers called honeycomb yielding damper (HYD) with different dimensions and thickness along with evaluating and comparing the force-displacement diagrams and investigating the seismic parameters of this type of yielding damper. All modeling and validation of numerical samples were done by Ansys software. Non-linear analysis method is used in this research. The hysteresis curves are obtained under in-plane cyclic loads. The mechanical parameters such as ductility ratio, initial hardness, effective hardness and damping coefficient can be determin. The results of this research showed that the effective stiffness increases by increasing the length and thickness of the sample. The ductility ratio decreases by increasing the height of the sample. the effective stiffness decreases by increasing the height of the sample. The ductility ratio increases by increasing the height of the sample. Also, the effective damping coefficient decreases with the increase in the height of the samples, the effective damping coefficient increases with the increase in length and thickness of the samples.

In the recent past, the application of various types of passive dampers (e.g., yielding metallic dampers) has become a common practice for improving seismic performance of the under-construction buildings and rehabilitation of existing constructions. In this study, a new elliptical metallic damper was introduced to improve the seismic behavior of existing steel structures. Among other parameters, geometrical characteristics are known to affect the seismic performance of the constructions rehabilitated with the proposed elliptical damper. Accordingly, the performance of the proposed damper was investigated through accurate numerical studies on various types of dampers considering various damper dimensions, ellipse major and minor axes length-to-plate thickness ratios, and placements of elliptical shear diaphragm. To study the proposed elliptical damper in terms of its effect on the seismic behavior of rehabilitated buildings, three benchmark structures with 3, 9, and 20 stories were used. Further, far-field and near-field earthquake records were used to undertake nonlinear dynamic analyses. In this work, the proposed elliptical damper was verified by the Abaqus finite-element software, and nonlinear time-history analyses were conducted in the SAP2000 software to check for seismic performance of rehabilitated structural frames with the considered damper. Results of the nonlinear dynamic analyses indicated the appropriate performance of the proposed elliptical damper in terms of reducing the seismic responses of the rehabilitated structures and suitable behavior of the proposed elliptical damper in dissipating the imposed earthquake energy to the structures. Based on these results, upon rehabilitation with the proposed damper, the 3-, 9-, and 20-story structures exhibited smaller maximum lateral roof displacements by 66, 64, and 31%, respectively.

Connections play a crucial role in structures, including steel structures, and have a significant impact on the seismic behavior of the structure. One particular type of connection commonly used in steel structures is the Reduced Beam Section (RBS). This connection reduces the moment strength of the beam near the column, which in turn results in less moment being transferred to the column at the final moment. The study involved 30 numerical analyses conducted using ABAQUS to examine two cases. The first case involved investigating a connection with a beam that had a hole in the flange area. The variables examined included the area of the flange holes and the axial force of the column. In the second case, a yield ring was utilized in the flange area of the beam. The radius of the yield ring was considered as a variable insix different cases. Equations for calculating the maximum strength moment and analyzing the linear region of a beam were presented in the study. The yielding damper must yield earlier than other members, and an equation was provided to ensure that it does. Finally, the cyclic behavior of the two models was also compared. Numerical analysis revealed that if the area of the flange holes is half that of the beam flanges, the beam's strength does not significantly decrease withincreasing axial force. The elastic stiffness and ductility of the SRD-equipped connection were higher than the RBS model, with the SRD model achieving 1.8 and 2.6 times greater ductility and elastic stiffness, respectively, in the most optimal state.

The concrete structures exposed to the earthquake have the potential of cracking and reduction in stiffness and strength. Because of their low deformability, there would be some cracking and plastic hinging in the moment-resisting frame. The utilization of dampers is a solution to improve the behavior of the constructed structures. dampers play a crucial role in improving structural performance level and bearing capacity. In the present study, 9 concrete frames were tested, and steel yield dampers have been used for the seismic rehabilitation of the concrete moment-resisting frames. The yield dampers elements are ADAS dampers (Added Damping and Stiffness) connected to the concrete frame using steel braces. The concentric-type steel braces connect the dampers and concrete beams. Furthermore, to investigate the influence of the braces on the structure’, s strength and behavior three concentrated braces have been installed in the structure. The structure in which ADAS dampers was employed demonstrated more strength and less recorded damages than the simple moment-resisting frame. In the present study, the effect of braces and dampers have been investigated in the behavior of the structure, cracking, and strength. The strength of the frames was increased by 48% and 21% by employing steel braces and yield dampers in the concrete frames, respectively, comparing the control frame.

Having a long history of seismicity and experienced destructive and deadliest earthquakes make Iran one of the vulnerable countries against earthquakes. Based on the seismic hazard zoning map presented in the Iranian seismic code (2800 provisions), more than 90% of Iranian cities are located in areas with high or very high seismic hazard zones. On the other hand expansion of urbanization in recent decades almost comprises reinforced concrete (RC) buildings. Many of these RC structures constructed in accordance with codes that did not mandate adequate detailing and reinforcement for seismic protection, may have already suffered damage since their erection, due to insufficient maintenance, earthquake activity, or other natural hazards. Therefore providing appropriate solutions for the rehabilitation of such structures has always been considered essential. Metallic energy dissipators have been grown experimentally and theoretically almost for steel structures. U-shaped metallic-yielding damper as one of the most well-known metallic energy dissipators has also developed as a lateral-load resisting system for strengthening existing steel frames. Experimental and theoretical results showed that U-shaped metallic dampers can operate with large displacements in the inelastic range and dissipate energy through the plastic deformation of the steel. The purpose of this study is to take potential advantages of this system to strengthen deficient RC structures. To the best of the authors’ knowledge, this issue has rarely been considered, most of which are limited to small experimental studies. Therefore, it can be useful to study this issue numerically at the real size structural level. In this regard, three RC intermediate moment frames in 4, 6, and 8 stories and irregular in elevation are considered. Irregularity is considered by a setback in elevation of the frames as a special type of irregularity with considerable effect on seismic performance. Frames were first designed deficiently by SAP2000 software according to the provisions of the Iranian national building code and Iranian seismic code for the intermediate reinforced concrete moment-resisting frames. Then the frames strengthen by adding U-shaped metallic-yielding dampers together with inverted V-braces. The nonlinear dynamic time-history analysis is performed on all frames subjected to three far source input motions utilizing PERFORM 3D software. Nonlinear specifications of beams and columns are considered by assigning plastic hinges to them in addition to defining nonlinearity for the dampers. The results of roof displacement, base shear, inter-story drifts, and performance of frames at the life safety structural performance level are monitored for both cases with and without dampers. The use of U-shaped metallic dampers has always reduced significantly the maximum lateral displacement of the buildings. On average, under the three records of Imperial Valley, Manjil, and Tabas, the reduction is obtained as 32, 33, and 22 for 4, 6, and 8 story frames, respectively. Such a significant reduction is also visible in the inter-story drifts.  . No major effect on the maximum base shear force is observed and even in some cases, it is increased up to 10%. Failure of frames reduced by transferring nonlinearity of elements to the dampers and seismic performance assessment indicates that dampers strengthen frames to almost satisfy the requirements of the life safety level.

The present article seek to investigate the function of elliptical steel damper function in steel frames seismic resisting. The elliptical damper is a kind of earthquake energy dissipater in structure which acts based on the steel yielding feature. Thus, this damper in frame lateral displacement mechanism is expected to have a satisfying hysteretic behavior in terms of energy absorption is on acceptable level. To study the EADAS (elliptical added damping and stiffness) elliptical damper function Abaqus software was used in seismic resisting of steel frames. To do the analysis one span- one floor which was modeled with eight kinds of suggested damper was used. The basis of the analysis method is based on the finite element method and a cyclic loading curve was used and the frame will be pushed to the failure of the dampers. The results of the present study indicates that through the addition of this damper with the damage focus in damper the structure elements remain in elastic zone and without any damage bear the lateral load. The damper causes an increase in ductility and the frame energy absorption hysteretic and it can be used for seismic resisting of steel frames.

yielding dampers are widely regarded as an effective method for reducing the destructive effects of earthquakes due to their high energy absorption capability and enhancement of structural stability. elliptical roller damper integrates rollers into the conventional elliptical damper that is a yielding type, enabling it to sustain substantial gravity and vertical earthquake loads, and alleviates the dead load imposed on other components within the gravity load-bearing system. In this study, the performance of the elliptical roller damper, as an optimized example of such dampers, was investigated. Using numerical modeling in Abaqus software, the effects of geometric parameters such as length, width, thickness, height, and the number of rollers on the damper's performance were analyzed. The results showed that increasing the width and thickness and reducing the height significantly improved the energy absorption capacity and lateral strength of the damper, while increasing the length and number of rollers had no effect on the hysteresis curve but contributed to the stability of the damper under gravity loads. Furthermore, the elliptical roller damper demonstrated stable hysteresis loops in various loading angles, indicating its capacity to withstand different directions of loading. Finally, an optimized design for using this damper in seismic isolators was proposed, which is expected to effectively reduce the transfer of seismic energy to the structure and enhance its overall stability.

Concentric bracing systems are a popular solution for strengthening moment frames due to their high lateral stiffness, ease of installation, and low cost. However, buckling in compression members can result in sudden loss of strength and less deformability. Researchers have suggested using steel slit dampers to increase deformability and energy dissipation in this system by directing damage away from bracing members. In this study, 265 finite element models were analyzed in ABAQUS software based on previous experimental investigations and the installation configuration of the combined elliptical slit elements with Chevron bracing system in a moment frame. The effects of varying each geometric parameter of the element, including thickness, width, height, and number of slits, as well as the minor diameter of the elliptical slit, on the behavioral characteristics have been investigated in a three-dimensional parametric space. These characteristics are such as elastic stiffness, ductility, force capacity, and cyclic energy dissipation. Finally, and based on conducted numerical analysis, suitable ranges for each geometric parameter have been proposed to facilitate optimal design of the element.

Over years, the energy absorption process against different kinds of loading has always been one the most important issues in the engineering science. To address this, many kinds of dampers such as viscoelastic, friction, yielding, mass, and liquid dampers have been invented. Among all these dampers, steel yielding dampers are one of the most economic, available, suitable, and best choices for the long return period of seismic cyclic loading on structures. However, it seems that there are not sufficient studies on these dampers to convince the designers to use them widely. This research tries to show the effects of geometrical parameters on the energy absorption and cyclic behavior on a specific simple trapezoidal steel yielding damper using the finite element method, then the effect of using a new steel damper on base shear and roof acceleration responses of a three story building studied by nonlinear time history analysis. According to the results, there are some effective and less effective parameters whose variation such as geometrical parameters can seriously change the total energy absorption level and improve the damper hysteresis loops as well as ductility under specific cyclic loading and showed that using new steel damper will results the significant decreasing in base shear and roof acceleration of the building.