Seismic response sensitivity of the structures equipped with cylindrical frictional dampers to the value of slippage load (original) (raw)
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Seismic behavior of steel structures equipped with Cylindrical Frictional Dampers
During severe seismic excitations, a large amount of kinetic energy is fed into a structure. In this investigation, seismic response of steel structures utilizing Cylindrical Frictional Dampers (CFD) is studied. CFD is an innovative frictional damper which comprises two principal elements, the shaft and the hollow cylinder. These two elements are assembled such that one is shrink-fitted inside the other. If the damper’s axial force overcomes the static friction load, the shaft inside the cylinder will move and results in considerable mechanical energy absorption. To assess the efficacy of CFD, various steel frames are constructed and analyzed using OpenSees software. Nonlinear time history analyses and Incremental Dynamic Analysis (IDA) are applied to the frames and clear distinction has been drawn between the frames comprising CFD and the counterparts without CFD to emphasize the effectiveness of CFD in altering seismic responses. The results show that CFD extremely improves the se...
Response Modification Factor of Steel Structures Equipped with Cylindrical Frictional Dampers
2017
During severe seismic excitations, a large amount of kinetic energy is fed into a structure .In this investigation, seismic response of steel structures utilizing Cylindrical Frictional Dampers (CFD) is studied. CFD is an innovative frictional damper which comprises two principal elements, the shaft and the hollow cylinder. These two elements are assembled such that one is shrink-fitted inside the other. If the damper's axial force overcomes the static friction load, the shaft inside the cylinder will move and results in considerable mechanical energy absorption. To assess the efficacy of CFD, various steel frames are constructed and analyzed using OpenSees software. Nonlinear time history analyses and Incremental Dynamic Analysis (IDA) are applied to the frames and clear distinction has been drawn between the frames comprising CFD and the counterparts without CFD to emphasize the effectiveness of CFD in altering seismic responses. The results show that CFD extremely improves the seismic response of the structure
Numerical and experimental study of hysteretic behavior of cylindrical friction dampers
Engineering Structures, 2011
Frictional dampers utilize the mechanism of friction for absorbing and dissipating the energy imparted to the dynamic systems. Frictional dampers are widely used in mechanical systems in various industries in order to mitigate the impact and vibration effects. Frictional dampers are also utilized in structures as means of passive control to improve the seismic behavior of structures.In this investigation, an innovative type of frictional damper called cylindrical friction damper (CFD) is proposed. This damper consists of two main parts, the inner shaft and the outer cylinder. Dimensions and properties of the main parts are defined based on seismic demand of structures. These two parts are assembled such that one is shrink fitted inside the other. Upon application of proper axial loading to both ends of the CFD, the shaft will move inside the cylinder by overcoming the friction. This in turn leads to considerable dissipation of mechanical energy. In contrast to other frictional dampers, the CFDs do not use high-strength bolts to induce friction between contact surfaces. This reduces construction costs, simplifies design computations and increases reliability in comparison with other types of frictional dampers.The hysteretic behavior of CFD is studied by experimental and numerical methods. The results show that the proposed damper has great energy absorption by stable hysteretic loops, which significantly improves the performance of structures subjected to earthquake loads. Also, a close agreement between the experimental and numerical results is observed.► An innovating type of friction damper called CFD is introduced. ► The hysteretic behavior of CFD is studied by experimental and numerical methods. ► It is shown that CFD is highly effective to reduce earthquake damages on structure.
COMPDYN Proceedings, 2022
The study presents the design, experimental characterization and modeling of a novel friction damper with enhanced resistance to repeated seismic loads. This device provides energy dissipation by the friction force triggered between a moving shaft and a lead core prestressed within a rigid steel chamber. As there are not mechanical parts that are subjected to cyclic stresses, there is no risk of fatigue and the damper is expected to resist to a virtually unlimited number of load cycles. Two prototypes of the friction damper were tested according to the procedure established in the European standard EN 15129 for Displacement Dependent Devices, fulfilling the relevant requirements. The damper provides a stable response over repeated cycles, characterized by an essentially rectangular hysteresis loop with an equivalent viscous damping ratio ξeff of more than 55%. Moreover, the damper is characterized by a low sensitivity to the loading rate and by the ability to withstand multiple cycles of motion at the design earthquake displacement without deterioration of performance, providing maintenance-free operation in presence of repeated ground shakes. A 3D finite element model of the friction damper is formulated in Abaqus and validated upon the results of the experimental tests. The model is then used in a parametric study to investigate the influence of the diameters of the shaft on the output force. The numerical data points are fitted by a simple model which can be used for designing the damper according to a specific quasi-static force.
PERFORMANCE EVALUATION OF FRICTION DAMPERS UNDER SEISMIC LOADS.doc
Several structural control techniques such as passive, active, semi active and hybrid control techniques are gaining importance in earthquake resistant design of structures. Friction damper is a passive type energy dissipating device, which dissipates the seismic energy by virtue of the solid friction developed between the two sliding surfaces. Friction dampers get activated at their slip load and starts dissipating energy. The maximum energy dissipation and least response of the structure occur at optimal slip load of friction dampers. In the present study, the optimal slip load of the friction dampers provided in a nine storey reinforced concrete frame model was evaluated analytically using nonlinear time history analysis. Then the effect of friction dampers on the displacements and forces in the structure was evaluated. Acceleration time histories of El Centro ground motion (N-S component) and Indian seismic zone IV were used for the analysis. The analyses were carried out using SAP2000 computer package. The results confirmed that a good reduction in the displacements and forces is possible with the addition of friction dampers and hence it can be used as an alternative for the conventional ductility based design methods.
Performance of steel frames with a new friction damper device under earthquake excitation
Engineering Structures, 2002
A study on the dynamic response of single-storey steel frames equipped with a novel friction damper device (FDD) is presented. Extensive testing was carried out for assessing the friction pad material, damper unit performance and scaled model frame response to lateral harmonic excitation. Numerical simulations based on non-linear time history analysis were used to evaluate the seismic behaviour of steel frames with inserted FDD. The governing parameters were identified and their influence was traced and summarised along with implications for practical design. The application of the new FDD presents a feasible alternative to the conventional ductility-based earthquake-resistant design both for new construction and for upgrading existing structures.
2008
Rotational friction damper (RFD) was introduced in 2000. Primary experimental and numerical studies were done in Denmark. Optimal slip load has the most importance in performance of friction damper. Optimal slip load can be obtained from the minimum of performance indexes. There are two performance indexes, seismic performance index (SPI) and relative performance index (RPI). In this paper three frames equipped with rotational friction damper, are modeled. These frames are studied with different slip loads, acceleration records and PGAs and 540 nonlinear dynamic time history analyses were done to specify the optimal slip loads. The results show that different performance indexes can give similar slip load. Performance of RFD is improved by increasing the heights of the frame. Damage index significantly decreases in optimal slip load. .
Analysis, Design and Applications of Rotational Friction Dampers for Seismic Protection
The paper introduces the basic types of damping devices and summarizes the benefits of implementing supplemental damping systems for seismic protection of buildings and other structures. A novel damper device based on the rotational friction hinge concept invented by the first author is described. The slip capacity of the device and its energy dissipation capacity can be easily increased by adding more layers of steel plates and friction pads. The experimental evaluation of the original damper unit was first carried out in DTU, Denmark under displacement and forcing frequency control. The friction pads were made from advanced material capable of sustaining up to 400 cycles without property degradation. In 2001, an international team including the authors conducted intensive research program on a three-storey building equipped with rotational friction dampers at the largescale shake-table testing facility of the NCREE, Taiwan. The performance of the damped structure was examined for 14 cases of seismic input with peak ground acceleration (PGA) varying from 0.05g to 0.30g. The testing demonstrated the remarkable efficiency of the damping system for reducing the lateral displacements and interstorey drifts of the test building. Nonlinear time-history analyses were used for predicting the dynamic response of the structure and selecting adequate damper capacities. A few representative applications of RFDs for seismic protection of buildings and facilities in Europe and Japan are given which demonstrate the reliability of the devices and their most typical arrangements within new and existing structures. It is concluded that the displacementdependent dampers such as friction and metallic are a powerful and nonexpensive engineering tool for solving vibrational problems both in new and existing structures.
INFLUENCE OF FRICTION DEVICES ON THE NONLINEAR SEISMIC RESPONSE OF STEEL STRUCTURES
This paper investigates the influence of friction devices on the nonlinear seismic response of steel structures. For this purpose a steel frame structure is designed according to the rules of the recent Eurocodes. Four frame types are investigated: type 0 (frame without friction devices), type 1 (friction devices only in the ground level), type 2 (friction devices in all the stories), type 3 (friction devices in all the stories except the ground level). The devices are placed as diagonal trusses in the middle bay of the frame. They are realized as slotted bolt connections. Alternative friction forces are considered. Nonlinear dynamic analyses are carried out for the evaluation of the structural response. The focus is on the maximum inter-story drift ratio (MISDR), which among the several response parameters is chosen as damage index. A set of natural accelerograms is used as seismic excitation for the analysis. Numerical results expose that friction devices reduce the seismic response of steel structures with appropriate number of devices and a sufficient amount of friction forces. Alternative calculations furnish the optimum topology for the devices and the corresponding amounts of friction forces. The mean MISDR is reduced in the optimal case up to 57%, in comparison to the response of the frame without damping devices. Extreme values of the MISDR are also reduced, with a reduction percentage greater than 50%. Thus, friction devices can be used for the preseismic strengthening or postseismic rehabilitation of steel structures.
Effect of Friction Damper Placement on the Behaviour of Frame Structures under Seismic Actions
1st International Conference on Engineering Technology and Applied Sciences, 2016
Friction damping devices are relatively inexpensive and effective method for energy dissipation through the mechanism of solid friction generated at the sliding surface. It is crucial to provide a steady and predictable frictional response during the life of these devices. In this study, a numerical analysis was performed in order to investigate the placement of the friction dampers (FDs) on the behaviour of the structure under seismic loading. For this, 3 and 6 storey steel buildings with moment-resisting frames were taken into consideration. The case study buildings have the same plan and three bays on each direction. Two structures equipped with FDs placed in various locations throughout the structure were subjected to the earthquake loading. The structures were modelled using a finite element program and evaluated by the nonlinear analysis. The response of the structures in terms of local and global deformations was evaluated. The results exhibited that the damper placement in the structure had a considerable influence on the structural response of the frames under earthquake loading.