• Structural Engineering and Mechanics
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• v.89 no.1
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• pp.93-102
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• 2024

Using negative Poisson's ratio materials, an innovative metallic-yielding damper is introduced for the first time in this study. Through the use of ABAQUS commercial software, a nonlinear finite element analysis is conducted to determine the performance of the proposed system. Mild steel plates with elliptical holes are used for these types of dampers, which dissipate energy through an inelastic deformation of the constitutive material. To assess the capability of the proposed damper, nonlinear quasi-static finite element analyses have been conducted on the damper with a variety of geometric parameters. According to the results, the proposed system is ductile and has a high capacity to dissipate energy. The proposed auxetic damper has a specific energy absorption of 910.8 J/kg and a ductility of 33.6. Therefore, this damper can dissipate a large amount of earthquake input energy without buckling by increasing the buckling load of the brace with its ductile behavior. In addition, it was found that by incorporating auxetic dampers in the steel frame, the frame was made harder, stronger, and ductile and its energy absorption increased by 300%.

• Land and Housing Review
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• v.5 no.2
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• pp.107-114
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• 2014

Passive energy dissipation systems for seismic applications have been under development for a number of years with a rapid increase in implementations starting in the mid-1990s in many countries. A metallic hysteretic damper has most commonly been used for seismic protection of structures in domestic area because they present high energy-dissipation potential at relatively low cost and easy to install and maintain. This paper presents an analytical case study of the effectiveness of isotropic hysteretic metallic damper(IHMD) called Kagome as a passive dissipative device in reducing structural response during seismic excitation. An eighteen-story RC framed apartment building is studied with and without IHMD. Results demonstrate the feasibility of these techniques for seismic mitigation. The inclusion of supplemental passive energy dissipation devices in the form of IHMD proved to be a very effective method for significantly reducing the seismic response of the building investigated.

• Journal of Korean Society of Steel Construction
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• v.24 no.2
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• pp.149-161
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• 2012

The use of seismic energy-dissipative devices for passive control is increasing exponentially in the recent years for both new and existing buildings. Use of these devices started in and has been somewhat limited to developed countries. One of the current challenges is to promote the use of seismic dampers in earthquake-prone developing countries by lowering the cost of the devices. This paper proposed a new type of seismic damper based on yielding of a cantilever type metallic element for seismic retrofit of existing and new building structures. The hysteretic behavior and energy dissipation capacity of the proposed damper was investigated using component tests under cyclic loads. The experimental results indicated that the damping device had stable restoring force characteristics and a high energy dissipation capacity. Based on these results, a simple hysteretic model for predicting the load-displacement curve of the seismic damper was proposed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.3
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• pp.123-130
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• 2010

The aim of this paper is a seismic performance evaluation of metallic damper devices which are efficient in workability and installation process. For this V shape and S shape dampers is considered. The strut figures of dampers are V shape and S shape and, the research parameters are strut height and angle of the dampers. ABAQUS program is used for nonlinear finite element analysis. The analysis is performed with the hysteretic curve that has maximum displacement with 50mm and has increased progressive. As a results of evaluating the yield strength, maximum strength and energy dissipation capacity of each device, V and S shape have a good strength capacity and the devices with strut angle $60^{\circ}$ and strut height 140 and 200mm are evaluated stable in seismic behaviors. The response of S shape is more efficient than that of V shape. In the yield strength estimation process, proposed formula can not estimate the yield strength of V and S shape dampers. Even though, the formula can not consider the variation of strut heights and strut angles. Finally the S shape damper is recommended in seismic performance than V shape damper.

• Structural Engineering and Mechanics
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• v.56 no.4
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• pp.569-588
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• 2015

A comprehensive methodology is proposed for design of metallic dampers in seismic retrofit of earthquake-damaged frame structures. It is assumed that the metallic dampers remain elastic and only provide stiffness during frequent earthquake (i.e., earthquake with a 63% probability of exceedance in 50-year service period), while in precautionary earthquake (i.e., earthquake with a 10% probability of exceedance in 50-year service period), the metallic dampers yield before the main frame and dissipate most of the seismic energy to either prevent or minimize structural damages. Therefore by converting multi-story frame to an equivalent single-degree-of-freedom system, the added stiffness provided by metallic dampers is designed to control elastic story drifts within code-based demand under frequent earthquake, and the added damping with the combination of added stiffness influences is obtained to control structural stress within performance-based target under precautionary earthquake. With the equivalent added damping ratio, the expected damping forces provided by metallic dampers can be calculated to carry out the configuration and design of metallic dampers along with supporting braces. Based on a detailed example for retrofit of an earthquake-damaged reinforced concrete frame by using metallic dampers, the proposed design procedure is demonstrated to be simple and practical, which can not only meet current China's design codes but also be used in retrofit design of earthquake-damaged frame with metallic damper for reaching desirable performance objective.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.5
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• pp.78-86
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• 2014

The purpose of this study is the displacement and velocity dependence evaluation of I type and S type metallic dampers. For this purpose, 12 metallic damper specimens are prepared and dependence test are performed. Test variables are strut type, displacement and velocity dependence. From the evaluation results of dependence tests, number of cycles are fully exceeded than minimum 5 cycles described in ASCE 7-10. According to displacement dependence test results, larger target displacement (50mm) shows lower cyclic numbers and cumulated energy dissipated area than lower target displacement (25mm). Also it show higher strength and early failure than short target displacement. In velocity dependence evaluation, fast target velocity (60mm/sec) shows lower cyclic numbers and cumulated energy dissipated area than target velocity (40mm/sec). As a results of basic properties, dependence evaluation and cumulated energy dissipated area evaluation, dependence capacity of S type metallic damper is far superior than I type.

• Steel and Composite Structures
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• v.47 no.2
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• pp.185-201
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• 2023

Despite the high lateral stiffness and strength of the Concentrically Braced Frame (CBF), due to the buckling of its diagonal members, it is not a suitable system in high seismic regions. Among the offered methods to overcome the shortcoming, utilizing a metallic damper is considered as an appropriate idea to enhance the behavior of Concentrically Braced Frames (CBFs). Therefore, in this paper, an innovative steel damper is proposed, which is investigated experimentally and numerically. Moreover, a parametrical study was carried out to evaluate the effect of the mechanism (shear, shear-flexural, and flexural) considering buckling mode (elastic, inelastic, and plastic) on the behavior of the damper. Besides, the necessary formulas based on the parametrical study were presented to predict the behavior of the damper that they showed good agreement with finite element (FE) results. Both experimental and numerical results confirmed that dampers with the shear mechanism in all buckling modes have a better performance than other dampers. Accordingly, the FE results indicated that the shear damper has greater ultimate strength than the flexural damper by 32%, 31%, and 56%, respectively, for plates with elastic, inelastic, and plastic buckling modes. Also, the shear damper has a greater stiffness than the flexural damper by 43%, 26%, and 53%, respectively, for dampers with elastic, inelastic, and plastic buckling modes.

• Steel and Composite Structures
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• v.50 no.6
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• pp.721-734
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• 2024

In this research, the efficiency of a metallic energy dissipation device for seismic retrofit of an existing structure is evaluated by cyclic loading test. The proposed device, which is called multi-slit damper, is made of weak and strong slit dampers connected in series. Its energy dissipation mechanism consists of two stages: (i) yielding of the weak-slit damper under minor earthquakes; (ii) restraint of further deformations of the weak slit damper and activation of the strong slit damper under major earthquakes using a gap mechanism. A reinforced concrete (RC) frame with characteristics similar to soft-first-story structures is tested under cyclic loading before and after retrofit using the proposed device. The details of the experimental study are described and the test is simulated in an available commercial software to validate the analytical model of the damper. To further verify the applicability of the damper, it is applied to an analysis model of a 4-story structure with soft first story and its seismic performance is evaluated before and after retrofit. The experimental and analysis results show that the multi-slit damper is effective in controlling seismic response of structures.

• Structural Engineering and Mechanics
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• v.81 no.3
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• pp.317-333
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• 2022

Visco-Plastic Damper (VPD) as a passive energy dissipation device with dual behavior has been recently numerically studied. It consists of two bent steel plates and segments with a viscoelastic solid material in between, combining and improving characteristics of both displacement-dependent and velocity-dependent devices. In order to trust the performance of VPD, for the 1st time this paper experimentally investigates prototype damper behavior under a wide range of frequency and amplitude of dynamic loading. A high-axial damping rubber is innovatively proposed as the viscoelastic layer designed to withstand large axial strains and dissipate energy accordingly. Test results confirmed all assumptions about VPD. The behavior of VPD subjected to low levels of excitation is elastic while with increasing levels of excitation, a significant source of energy dissipation is provided through the yielding of the steel elements in addition to the viscoelastic energy dissipation. The results showed energy dissipation of 99.35 kN.m under a dynamic displacement with 14.095 mm amplitude and 0.333 Hz frequency. Lateral displacement at the middle of the device was created with an amplification factor obtained ranging from 2.108 to 3.242 in the rubber block. Therefore, the energy dissipation of viscoelastic material of VPD was calculated 18.6 times that of the ordinary viscoelastic damper.

• International journal of steel structures
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• v.18 no.5
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• pp.1741-1753
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• 2018

Metallic dampers are sacrificial devices (fuses) that dissipate significant energy during earthquakes while protecting other parts of structures from possible damage. In addition to numerous implementation opportunities of other base isolation systems, U-shaped dampers (UD) are one of the widely investigated and used devices in practice especially in Japan. The present study focuses on enhancing seismic performance of these types of dampers by changing their geometric properties. UDs with perforated (i.e. with holes) and/or nonparallel arms are developed for this purpose. For a better comparison, the criterion of equal material volume (or mass) has been utilized. Three dimensional finite element models of the new type of UDs are formed and investigated numerically under selected displacement histories. Based on the obtained hysteretic curves; dissipated energy intensities, effective stiffness ratios, reaction forces, effective damping ratios are evaluated in this parametric study. It is found that both damper types have merits in use of seismic applications and that the selection of the damper configuration is dependent on the design specific issues.