• Steel and Composite Structures
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• v.13 no.6
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• pp.501-519
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• 2012

As an alternative to current conventional force-based assessment methods, the energy-based seismic performance of a code-designed 20-storey high-rise steel building is evaluated in this paper. Using 3D nonlinear dynamic time-history method with consideration of additional material damping effect, the influences of different restoring force models and P-${\Delta}/{\delta}$ effects on energy components are investigated. By combining equivalent viscous damping and hysteretic damping ratios of the structure subjected to strong ground motions, a new damping model, which is amplitude-dependent, is discussed in detail. According to the analytical results, all energy components are affected to various extents by P-${\Delta}/{\delta}$ effects and a difference of less than 10% is observed; the energy values of the structure without consideration of P-${\Delta}/{\delta}$ effects are larger, while the restoring force models have a minor effect on seismic input energy with a difference of less than 5%, but they have a certain effect on both viscous damping energy and hysteretic energy with a difference of about 5~15%. The paper shows that the use of the hysteretic energy at its ultimate state as a seismic design parameter has more advantages than seismic input energy since it presents a more stable value. The total damping ratio of a structure consists of viscous damping ratio and hysteretic damping ratio and it is found that the equivalent viscous damping ratio is a constant for the structure, while the equivalent hysteretic damping ratio approximately increases linearly with structural response in elasto-plastic stage.

• Steel and Composite Structures
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• v.32 no.6
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• pp.717-729
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• 2019

A horizontal cyclic test was carried out to study the seismic performance of lightweight aggregate concrete filled steel tube (LACFST). The constitutive and hysteretic model of core lightweight aggregate concrete (LAC) was proposed for finite element simulation. The stress and strain changes of the steel tube and concrete filled inside were measured in the experiment, and the failure mode, hysteresis curve, skeleton curve, and strain curve of the test specimens were obtained. The influence of axial compression ratio, diameter-thickness ratio and material strength were analysed based on finite element model. The results show that the hysteresis curve of LACFST indicated favourable ductility, energy dissipation, and seismic performance. The LACFST failed when the concrete in the bottom first crushed and the steel tube then bulged, thus axial force imposed by prestressing was proved to be feasible. The proposed constitutive model and hysteretic model of LAC under the constraint of its steel tube was reliable. The bearing capacity and ductility of the specimen increase significantly with increasing thickness of the steel tube. The bearing capacity of the member improves while the ductility and energy dissipation performance slightly decreased with the increasing strength of the steel and concrete.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.415-420
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• 2009

This paper presents a position tracking control of a flexible beam using the piezoelectric actuator. This is achieved by implementing both feedforward hysteretic compensator of the actuator and PID feedback controller. The Preisach model is adopted to develop the feedforward hysteretic compensator. In the design of the compensator, estimated displacement of the piezoceramic actuator is used on the basis of the limiting triangle database that results from collecting data of the main reversal curve and the first order ascending curves. Experimental implementation is conducted for position tracking control and performance comparison is made between a PID feedback controller without considering the effect of hysteresis, and a PID feedback controller integrated with the feedforward hysteretic compensator.

• Journal of KSNVE
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• v.9 no.2
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• pp.258-264
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• 1999

The purpose of this paper is to investigate the damping behavior of a flexible joint. The slip at a structrual joint is selected at the tips of two identical cantilever beams adjoining each other. Both the direction of normal force and its magnitude varies due to the global deformation of the structure from mode to mode in the friction model. The friction dependent on vibration displacements resultsin the same functional behavior of the hysteretic material damping. Linearized energy loss factors are obtained as functions of both linear and torsional spring stiffness for their groups of symmetric and anti-symmetric modes, respectively. Experimental measurements as made for comparisons with analytical estimations by controlling the magnitude of fastening torque in the fastener, Hi-Lite. Trends on damping levelsmeasured in a very common vibration test method make an excellent agreement on the estimated damping levels.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.03a
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• pp.85-92
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• 2003

Hysteretic behaviors of a seismic isolator are identified by using the regularized output error estimator (OEE) based on the secant stiffness model. A proper regularity condition of tangent stiffness for the current OEE is proposed considering the regularity condition of Duhem hysteretic operator. The proposed regularity condition is defined by 12-norm of the tangent stiffness with respect to time. The secant stiffness model for the OEE is obtained by approximating the tangent stiffness under the proposed regularity condition by the secant stiffness at each time step. A least square method is employed to minimize the difference between the calculated response and measured response for the OEE. The regularity condition of the secant stiffness is utilized to alleviate ill-posedness of the OEE and to yield numerically stable solutions through the regularization technique. An optimal regularization factor determined by geometric mean scheme (GMS) is used to yield appropriate regularization effects on the OEE.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.206-209
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• 2006

This study presents the performance evaluation of a tuned mass damper (TMD) for controlling seismic responses of the nonlinear hysteretic structure represented by a Bouc-Wen model, considering that the general reinforce concrete building structures subject to earthquake load show nonlinear hysteretic behavior. Numerical analysis result indicates that the performance of a passive TMD of which design parameters are optimized for a elastic structure deteriorates when the hysteretic portion of the structural responses increases, while a semi-actively operated TMD shows about 15-40% more response reduction than the TMD.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.482-485
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• 2006

The response of a reinforced concrete element under cyclic shear is characterized by the hysteretic loops of the shear stress-strain curves. These hysteretic loops can exhibit strength deterioration, stiffness degradation, and a pinched shape. Recent tests have shown that the orientation of steel grids in RC shear elements has a strong effect on the "pinching effect" in the post-yield hysteretic loops. When the steel grid was set at a 45 degree angle to the shear plane, there was no pinching effect and no strength deterioration. However, when the steel grid was set parallel to the shear plane, there was a severe pinching effect and severe strength deterioration with increasing shear strain magnitude. In this paper, two RC elements subjected to revered cyclic shear stresses are considered to study the effect of the steel grid orientation. The presence and absence of the pinching mechanism in the post-yield shear hysteretic loops is studied using the Rotating Angle Softened Truss Model (RA-STM) theory.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.10a
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• pp.214-224
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• 1999

The design response spectrum has been widely used in seismic design to estimate force and deformation demands of structures imposed by Earthquake Ground Motion (EQGM). Inelastic Design Response Spectra (IDRS) to specify design yielding strength in seismic codes are obtained by reducing the ordinates of Linear Elastic Design Response Spectrum (LEDRS) by strength reduction factor (R). Since a building is designed using reduced design spectrum (IDRS) rather than LEDRS in current seismic design procedures it allows structures behave inelastically during design level EQGM. Inelastic Response Spectra (IRS) depend not only on the characteristics of the expected ground motion at a given site, but also on the dynamic properties and nonlinear characteristics of a structure. However, it has not been explicitly investigated the effect of different hysteretic models on IRS. In this study, the effect of hysteretic models on IRS is investigated.

• Journal of the Earthquake Engineering Society of Korea
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• v.21 no.6
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• pp.303-310
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• 2017

The coupled shear wall system with coupling beams is an efficient structural system for high-rise buildings because it can provide excellent ductility and energy dissipation to the buildings. The objective of this study is to simulate the hysteretic behavior of diagonally reinforced concrete coupling beams including pinching and cyclic deteriorations in strength and stiffness using a numerical model. For this purpose, coupling beams are modeled with an elastic beam element and plastic spring element placed at the beam ends. Parameters for the analytical model was calibrated based on the test results of 6 specimens for diagonally reinforced concrete coupling beams. The analytical model with calibrated model parameters is verified by comparing the hysteretic curves obtained from analysis and experimental tests.

• Structural Engineering and Mechanics
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• v.82 no.2
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• pp.245-258
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• 2022

Many Structural Health Monitoring (SHM) methods have been proposed for structural damage diagnosis and prognosis. However, SHM for pinched hysteretic structures can be problematic due to the high level of nonlinearity. The model-free hysteresis loop analysis (HLA) has displayed notable robustness and accuracy in identifying damage for full-scaled and scaled test buildings. In this paper, the performance of HLA is compared with seven other SHM methods in identifying lateral elastic stiffness for a six-story numerical building with highly nonlinear pinching behavior. Two successive earthquakes are employed to compare the accuracy and consistency of methods within and between events. Robustness is assessed across sampling rates 50-1000 Hz in noise-free condition and then assessed with 10% root mean square (RMS) noise added to responses at 250 Hz sampling rate. Results confirm HLA is the most robust method to sampling rate and noise. HLA preserves high accuracy even when the sampling rate drops to 50 Hz, where the performance of other methods deteriorates considerably. In noisy conditions, the maximum absolute estimation error is less than 4% for HLA. The overall results show HLA has high robustness and accuracy for an extremely nonlinear, but realistic case compared to a range of leading and recent model-based and model-free methods.