scholarly journals Effects of Damping Uncertainties on Damping Reduction Factors

2016 ◽  
Vol 61 (2) ◽  
pp. 341 ◽  
Author(s):  
Baizid Benahmed ◽  
Malek Hammoutene ◽  
Donatello Cardone
Keyword(s):  
Monte Carlo ◽  
Energy Dissipation ◽  
Dynamic Response ◽  
Design Process ◽  
Coefficient Of Variation ◽  
Damping Ratio ◽  
Response Spectra ◽  
Energy Dissipation Capacity ◽  
Damping Estimation ◽  
Reduction Factors

It is apparent that the dynamic response of a building dependson its energy dissipation capacity, hence damping ratio. Thedamping value experienced by a building during an earthquakediffers significantly from the value specified in the design step.This introduces uncertainties in the design process of the building.It would be desirable to consider not only the effects ofuncertainties in loading but also the uncertainties in the structuralparameters. In this paper, the effects of uncertainties in the estimation ofdamping ratio ξ, on the use of Damping Reduction Factors (DRF) for the evaluation of high damping response spectra,are examined. Damping uncertainties are described by a lognormalprobability distribution, and the Monte Carlo techniqueis used to generate the random values of damping. Theaverage of the distribution is the deterministic value of damping (taken equal to 5%, 7.5%, 10%, 20%, 30% and 40%) whilethree different values of coefficient of variation are considered (i.e. 10%, 20% and 40%, respectively). All the DRF formulations found in the literature are not able totake into consideration damping uncertainties, leading to significantdiscrepancies in the high damping response spectra. Based on the results of this study, a new DRF formulation, ableto account for uncertainties in damping estimation, is tentatively proposed.

scholarly journals Estimation of Additional Equivalent Damping Ratio of the Damped Structure Based on Energy Dissipation

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Xiuyan Hu ◽  
Qingjun Chen ◽  
Dagen Weng ◽  
Ruifu Zhang ◽  
Xiaosong Ren
Keyword(s):  
Energy Dissipation ◽  
Damping Ratio ◽  
Theoretical Concept ◽  
Estimation Methods ◽  
External Excitation ◽  
Single Degree Of Freedom ◽  
Equivalent Damping ◽  
Seismic Motion ◽  
Practical Engineering ◽  
Energy Dissipation Capacity

In the design of damped structures, the additional equivalent damping ratio (EDR) is an important factor in the evaluation of the energy dissipation effect. However, previous additional EDR estimation methods are complicated and not easy to be applied in practical engineering. Therefore, in this study, a method based on energy dissipation is developed to simplify the estimation of the additional EDR. First, an energy governing equation is established to calculate the structural energy dissipation. By means of dynamic analysis, the ratio of the energy consumed by dampers to that consumed by structural inherent damping is obtained under external excitation. Because the energy dissipation capacity of the installed dampers is reflected by the additional EDR, the abovementioned ratio can be used to estimate the additional EDR of the damped structure. Energy dissipation varies with time, which indicates that the ratio is related to the duration of ground motion. Hence, the energy dissipation during the most intensive period in the entire seismic motion duration is used to calculate the additional EDR. Accordingly, the procedure of the proposed method is presented. The feasibility of this method is verified by using a single-degree-of-freedom system. Then, a benchmark structure with dampers is adopted to illustrate the usefulness of this method in practical engineering applications. In conclusion, the proposed method is not only explicit in the theoretical concept and convenient in application but also reflects the time-varying characteristic of additional EDR, which possesses the value in practical engineering.

A New Type of Hybrid-Passive-Damper

2010 ◽  
Vol 163-167 ◽  
pp. 4367-4372
Author(s):  
Ai Rong Liu ◽  
Qi Cai Yu ◽  
Yuan Yao ◽  
Yu Zhu Guo
Keyword(s):  
Energy Dissipation ◽  
Damping Ratio ◽  
Loading Frequency ◽  
Vibration Period ◽  
Equivalent Damping ◽  
Passive Damper ◽  
New Type ◽  
Energy Dissipation Capacity ◽  
Relationship Of ◽  
The Relationship

This paper investigated the superelasticity and hysteresis characteristics of TiNi shape memory alloy ( SMA ) wire at room temperature, then the mechanical parameters of which were obtained. Based on the TiNi SMA wire and a purchased viscous damper, a new type of hybrid-passive-damper was designed and developed. Experiments were performed in order to validate the relationship of loading frequency and characteristic parameters such as energy dissipation capacity, equivalent damping ratio and equivalent stiffness. Experimental results show that hybrid-passive-damper designed in this paper has excellent energy dissipation capacity and is suitable for the vibration control of structures with long vibration period.

scholarly journals Experimental Quantification on the Residual Seismic Capacity of Damaged RC Column Members

2019 ◽  
Vol 13 (1) ◽  
Author(s):  
Chien-Kuo Chiu ◽  
Hsin-Fang Sung ◽  
Kai-Ning Chi ◽  
Fu-Pei Hsiao
Keyword(s):  
Energy Dissipation ◽  
Seismic Performance ◽  
Failure Modes ◽  
Shear Failure ◽  
Assessment Method ◽  
Seismic Capacity ◽  
Rc Column ◽  
Damage States ◽  
Energy Dissipation Capacity ◽  
Reduction Factors

Abstract To quantify the post-earthquake residual seismic capacity of reinforced concrete (RC) column members, experimental data for 6 column specimens with flexural, flexural–shear and shear failure modes are used to derive residual seismic capacity of damaged RC column members for specified damage states in this work. Besides of the experiment data, some related researches are also investigated to suggest the reduction factors of strength, stiffness and energy dissipation capacity for damaged RC column members, respectively. According to the damage states of RC columns, their corresponding seismic reduction factors are suggested herein. Taking an RC column with the flexural–shear failure for an example, its reductions factors of strength, stiffness and energy dissipation capacity are 0.5, 0.6 and 0.1, respectively. This work also proposes the seismic performance assessment method for the residual seismic performance of earthquake-damaged RC buildings. In the case study, this work selects one actual earthquake-damaged school building to demonstrate the post-earthquake assessment of seismic performance for a damaged RC building.

scholarly journals Cyclic Responses of Two-Side-Connected Precast-Reinforced Concrete Infill Panels with Different Slit Types

Buildings ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 16
Author(s):  
Guohua Sun ◽  
Fei Li ◽  
Qiyou Zhou
Keyword(s):  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Failure Mode ◽  
Damping Ratio ◽  
Concrete Strength ◽  
Plastic Hinge ◽  
Cyclic Behavior ◽  
Lateral Stiffness ◽  
Lateral Strength ◽  
Energy Dissipation Capacity

This study aimed to study the cyclic behavior of two-side-connected precast-reinforced concrete infill panel (RCIP). A total of four RCIP specimens with different slit types and height-to-span ratios modeled at a one-third scale were tested subjected to cyclic lateral loads. The failure mode, hysteretic behavior, lateral strength, stiffness degradation, ductility, and energy dissipation capacity of each RCIP specimen were determined and analyzed. The specimens experienced a similar damage process, which involved concrete cracking, steel rebar yielding, concrete crushing, and plastic hinge formation. All the specimens showed pinched hysteretic curves, resulting in a small energy dissipation capacity and a maximum equivalent viscous damping ratio lower than 0.2. The specimens with penetrated slits experienced ductile failure, in which flexural hinges developed at both slit wall ends. The application of penetrated slits decreased the initial stiffness and lateral load-bearing capacity of the RC panel but increased the deformation capacity, the average ultimate drift ratios ranged from 1.41% to 1.99%, and the lowest average ductility ratio reached 2.48. The specimens with high-strength concrete resulted in a small slip no more than 1 mm between the RC panel and steel beam, and the channel shear connectors ensured that the RC infill panel developed a reliable assembly with the surrounding steel components. However, specimens with concealed vertical slits (CVSs) and concealed hollow slits (CHSs) achieved significantly higher lateral stiffness and lateral strength values. Generally, the specimens exhibited two-stage mechanical features. The concrete in the CVSs and CHSs was crushed, and flexural plastic hinges developed at both ends of the slit walls during the second stage. With increasing concrete strength, the initial lateral stiffness and lateral strength values of the RCIP specimens increased. With an increasing height-to-span ratio, the lateral stiffness and strength of the RC panels with slits decreased, but the failure mode remained unchanged.

Performance of a Lead Rubber Damper under Cyclic Lateral Loading

2015 ◽  
Vol 764-765 ◽  
pp. 329-333
Author(s):  
Hee Cheul Kim ◽  
Young Hak Lee ◽  
Ha Eun Park ◽  
Dae Jin Kim ◽  
Jung Woo Park ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Shear Strain ◽  
Shear Force ◽  
Damping Ratio ◽  
Lateral Loading ◽  
Effective Stiffness ◽  
Energy Dissipation Capacity ◽  
Rubber Damper ◽  
Ratio Energy

This study investigates the performance of a new lead rubber damper (LRD), which is more advanced than existing lead-rubber based isolation devices. In contrast to the existing devices, multiple lead cores are installed in the LRD in order to optimize the behavior of the laminated rubber and lead. It is able to perform effectively under the application of shear force. An experiment was performed to investigate its dependency on the level of shear strain and frequency. The damping ratio, energy dissipation capacity and effective stiffness of the device were also evaluated.

scholarly journals Equivalent Viscous Damping Ratio Model for Flexure Critical Reinforced Concrete Columns

2018 ◽  
Vol 2018 ◽  
pp. 1-15
Author(s):  
Qin Zhang ◽  
Zong-yan Wei ◽  
Jin-xin Gong ◽  
Ping Yu ◽  
Yan-qing Zhang
Keyword(s):  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Damping Ratio ◽  
Hysteretic Behavior ◽  
Viscous Damping ◽  
Ratio Model ◽  
Rc Columns ◽  
Equivalent Viscous Damping ◽  
Rc Structures ◽  
Energy Dissipation Capacity

In order to determine the energy dissipation capacity of flexure critical reinforced concrete (RC) columns reasonably, an expression for describing the hysteretic behavior including loading and unloading characteristics of flexure critical RC columns is presented, and then, a new equivalent viscous damping (EVD) ratio model including its simplified format, which is interpreted as a function of a displacement ductility factor and a ratio of secant stiffness to yield stiffness of columns, is developed based on the proposed hysteretic loop expression and experimental data from the PEER column database. To illustrate the application of the proposed equivalent damping ratio model, a case study of pushover analysis on a flexure critical RC bridge with a single-column pier is provided. The analytical results are also compared with the results obtained by other models, which indicate that the proposed model is more general and rational in predicting energy dissipation capacity of flexure critical RC structures subjected to earthquake excitations.

Verification of spectral reduction factors for seismic assessment of bridges

2009 ◽  
Vol 42 (2) ◽  
pp. 111-121 ◽  
Author(s):  
C. Casarotti ◽  
R. Monteiro ◽  
R. Pinho
Keyword(s):  
Energy Dissipation ◽  
Static Analysis ◽  
Time History ◽  
Degree Of Freedom ◽  
Nonlinear Static Analysis ◽  
Mdof Systems ◽  
Spectral Reduction ◽  
Energy Dissipation Capacity ◽  
Nonlinear Static ◽  
Reduction Factors

Within a nonlinear static analysis procedure perspective for the assessment of structures, one of the key issues is the employment of a demand spectrum that takes also into account, through an adequate reduction of its spectral ordinates, the hysteretic energy dissipation capacity of the structure being assessed. There are certainly a relatively large number of past parametric studies dedicated to the validation of different approaches to translate such structural energy dissipation capacity into spectral reduction factors, however such studies have focused mainly, if not exclusively, on single-degree-of-freedom (SDOF) systems. It seems, therefore, that verification on full structural systems, such as complete bridges, is conspicuously needed in order to verify the adequacy of using existing SDOF-derived relationships in the assessment of multiple-degree-of-freedom (MDOF) systems. In this work, eleven different spectral reduction proposals, involving diverse combinations of previously proposed equivalent damping and spectral reduction equations, are evaluated, for various intensity levels, using a preliminarily validated nonlinear static procedure. A wide set of bridges, covering regular and irregular configurations as well as distinct support conditions, is used. The accuracy of the results is checked by direct comparison with Time-History Analyses performed with ten real ground motion records. Overall conclusions are then presented with the purpose of providing practitioners and researchers with indications on the most adequate spectral reduction schemes to be employed in nonlinear static analysis of bridges.

Experimental Study on the Effect of Moisture Content on Hysteretic Behavior of Reinforced Concrete Columns

2018 ◽  
Vol 12 (1) ◽  
pp. 47-61
Author(s):  
Wenjuan Lv ◽  
Baodong Liu ◽  
Ming Li ◽  
Lin Li ◽  
Pengyuan Zhang
Keyword(s):  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Moisture Content ◽  
Early Stage ◽  
Damping Ratio ◽  
Concrete Columns ◽  
Hysteretic Behavior ◽  
Cyclic Test ◽  
Experimental Result ◽  
Reinforced Concrete Columns

Background: For reinforced concrete structures under different humid conditions, the mechanical properties of concrete are significantly affected by the moisture content, which may result in a great change of the functional performance and bearing capacity. Objective: This paper presents an experiment to investigate the influence of the moisture content on the dynamic characteristics and hysteretic behavior of reinforced concrete column. Results: The results show that the natural frequency of reinforced concrete columns increases quickly at an early stage of immersion, but there is little change when the columns are close to saturation; the difference between the natural frequencies before and after cyclic test grows as the moisture content rises. The damping ratio slightly decreases first and then increases with the increase of moisture content; the damping ratio after the cyclic test is larger than before the test due to the development of the micro-cracks. Conclusion: The trend of energy dissipation is on the rise with increasing moisture content, although at an early stage, it decreases slightly. According to the experimental result, a formula for the moisture content on the average energy dissipation of reinforced concrete columns is proposed.

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