scholarly journals ESTIMATION OF EQUIVALENT VISCOUS DAMPING RATIO FOR PRESTRESSED REINFORCED CONCRETE BEAM IN CRUCIFORM BEAM-COLUMN SUBASSEMBLAGES

2009 ◽  
Vol 74 (644) ◽  
pp. 1831-1840
Author(s):  
Yuji TAJIMA ◽  
Kazuhiro KITAYAMA
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beam ◽  
Damping Ratio ◽  
Reinforced Concrete Beam ◽  
Viscous Damping ◽  
Equivalent Viscous Damping ◽  
Equivalent Viscous Damping Ratio

scholarly journals Seismic Material Properties of Reinforced Concrete and Steel Casing Composite Concrete in Elevated Pile-Group Foundation

2015 ◽  
Vol 22 (s1) ◽  
pp. 141-148 ◽  
Author(s):  
Mi Zhou ◽  
Wancheng Yuan ◽  
Yue Zhang
Keyword(s):  
Reinforced Concrete ◽  
Seismic Performance ◽  
Damping Ratio ◽  
Pile Group ◽  
Ocean Engineering ◽  
Static Loads ◽  
Equivalent Viscous Damping ◽  
Static Tests ◽  
Equivalent Viscous Damping Ratio ◽  
Positive Effect

Abstract The paper focuses on the material mechanics properties of reinforced concrete and steel casing composite concrete under pseudo-static loads and their application in structure. Although elevated pile-group foundation is widely used in bridge, port and ocean engineering, the seismic performance of this type of foundation still need further study. Four scale-specimens of the elevated pile-group foundation were manufactured by these two kinds of concrete and seismic performance characteristic of each specimen were compared. Meanwhile, the special soil box was designed and built to consider soil-pile-superstructure interaction. According to the test result, the peak strength of strengthening specimens is about 1.77 times of the others and the ultimate displacement is 1.66 times of the RC specimens. Additionally, the dissipated hysteric energy capability of strengthening specimens is more than 2.15 times of the others as the equivalent viscous damping ratio is reduced by 50%. The pinching effect of first two specimens is more obvious than latter two specimens and the hysteretic loops of reinforced specimens are more plumpness. The pseudo-static tests also provided the data to quantitatively assessment the positive effect of steel casing composite concrete in aseismatic design of bridge.

scholarly journals Study on the Aging Time Variation Law of Mechanical Properties of the Laminated Rubber Bearing in Coastal Bridges considering Frictional Slip

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yue Li ◽  
Chongming Gao ◽  
Chong Li ◽  
Qian Li
Keyword(s):  
Mechanical Properties ◽  
Aging Time ◽  
Damping Ratio ◽  
Viscous Damping ◽  
Equivalent Viscous Damping ◽  
Coastal Bridges ◽  
Shape Coefficient ◽  
Rubber Bearings ◽  
Frictional Slip ◽  
Equivalent Viscous Damping Ratio

As an important support member in the structural system of coastal bridges, the frictional slip and the rubber aging of laminated rubber bearings will affect the service safety of the overall structure in earthquakes. In order to investigate the mechanical properties aging law of the rubber bearings considering frictional slip in the coastal bridges, a frictional slip experiment was carried out on the laminated rubber bearings. Moreover, the influence of rubber aging on the mechanical properties of the bearings with various shape coefficients was analyzed by the finite element method during the 100 years of service life of bridges. The results indicate that (1) the horizontal and vertical stiffness of the bearing increase linearly with the aging time of the rubber. The amplification of the bearing stiffness also grows with the shape coefficient of the bearing. (2) The frictional slip initiation displacement of the bearing grows with the rubber aging time. Furthermore, the larger the shape coefficient of the bearing is, the more the frictional slip initiation displacement of the bearing increases. (3) With the increase of the aging time, the equivalent viscous damping ratio of the bearing continues to increase and more energy is consumed by frictional slip. For the bearing with the shape coefficient of 16.38, the equivalent viscous damping ratio at 100 years of rubber aging time is 1.17 times higher than that of the initial state of the bearing, and 33.21% more energy is consumed through frictional slip. Given that the marine environment accelerates rubber aging and changes the mechanical properties, the effects of the frictional slip and rubber aging properties of the laminated rubber bearings on the seismic dynamic response of bridges should be considered in the seismic design of coastal bridges.

Predominant period and equivalent viscous damping ratio identification for a full-scale building shake table test

2017 ◽  
Vol 46 (14) ◽  
pp. 2459-2477 ◽  
Author(s):  
Michelle C. Chen ◽  
Rodrigo Astroza ◽  
José I. Restrepo ◽  
Joel P. Conte ◽  
Tara Hutchinson ◽  
...  
Keyword(s):  
Damping Ratio ◽  
Full Scale ◽  
Shake Table Test ◽  
Viscous Damping ◽  
Shake Table ◽  
Equivalent Viscous Damping ◽  
Predominant Period ◽  
Equivalent Viscous Damping Ratio

Viscoelastic Damping of Ortho-Planar Springs

2008 ◽  
Author(s):  
Sterling Anderson ◽  
Brian D. Jensen
Keyword(s):  
Damping Ratio ◽  
Spring Constant ◽  
Viscoelastic Damping ◽  
Viscous Damping ◽  
Constrained Layer Damping ◽  
Equivalent Viscous Damping ◽  
Background Theory ◽  
Modal Damping ◽  
Damping Treatments ◽  
Equivalent Viscous Damping Ratio

This paper presents the design of a damped ortho-planar spring that uses viscoelastic constrained-layer damping to reduce the free response oscillations of the spring and suppress modal resonances in that response. Background, theory, and applications surrounding fully-compliant ortho-planar springs and viscoelastic damping treatments are first discussed. Next, the effect of various constrained layer thickness on the spring constant, damping ratio, equivalent viscous damping ratio, modal frequencies, and modal damping ratios are compared, and trends discussed. The results show that the equivalent viscous damping co-efficient of the viscoelastically-damped spring can be increased to nearly 2.5 times that of the reference configuration without significantly changing the size of the constraining layer or the spring constant of the ortho-planar spring. Viscoelastically-damped ortho-planar springs are also shown to successfully remove mechanical noise from a contact resistance test stand.

Quality Factors of Rotors With Hydrodynamic Bearings

1993 ◽  
Vol 115 (2) ◽  
pp. 261-265 ◽  
Author(s):  
J. S. Rao
Keyword(s):  
Quality Factor ◽  
Damping Ratio ◽  
Maximum Amplitude ◽  
Viscous Damping ◽  
Quality Factors ◽  
Equivalent Viscous Damping ◽  
Hydrodynamic Bearings ◽  
At Resonance ◽  
Equivalent Viscous Damping Ratio ◽  
Undamped Natural Frequency

The quality factor of a system is a measure of the maximum amplitude of vibration that occurs at resonance when the frequency of excitation is equal to the undamped natural frequency. This factor can be easily determined for a given mode of vibration, given its equivalent viscous damping ratio, as Q = 1/2ξ. Such a definition becomes complicated for a rotor mounted on hydrodynamic bearings. This note discusses some factors involved in estimating the quality factor of a rotor.

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.

Equivalent Viscous Damping Ratio of Steam Turbine Foundation in Nuclear Power Plants

2011 ◽  
Vol 148-149 ◽  
pp. 1113-1117
Author(s):  
Xiang Yang Zhou
Keyword(s):  
Steam Turbine ◽  
Concrete Structure ◽  
Stiffness Matrix ◽  
Composite Structures ◽  
Power Plants ◽  
Damping Ratio ◽  
Viscous Damping ◽  
Vibration Isolator ◽  
Equivalent Viscous Damping ◽  
Equivalent Viscous Damping Ratio

According to the complex damping theory, the formula to calculate equivalent damping ratio of composite structures is derived from damping stiffness matrix by dynamic analysis. The finite element model of a steam turbine foundation is established. The equivalent viscous damping ratio is calculated from natural frequencies, modes and structural stiffness matrix. Due to the vertical stiffness of spring vibration isolator is larger than lateral stiffness of concrete structure, most of free vibration modes of the foundation are movements of concrete structure. Therefore, the equivalent mode damping ratio is close to the one of concrete structure. The dynamic response is overestimated, if the equivalent mode damping ratio is derived from the average of spring vibration isolator and concrete structural ones.

Experimental investigation on joints between steel-reinforced concrete T-shaped column and reinforced concrete beam under bidirectional low-cyclic reversed loading

2016 ◽  
Vol 20 (3) ◽  
pp. 446-460 ◽  
Author(s):  
Ping Xiang ◽  
ZH Deng ◽  
YS Su ◽  
HP Wang ◽  
YF Wan
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beam ◽  
Hysteresis Loops ◽  
Reinforced Concrete Beam ◽  
Engineering Practice ◽  
Force Transmission ◽  
Equivalent Viscous Damping ◽  
Static Tests ◽  
Steel Reinforced Concrete ◽  
Reversed Loading

Steel-reinforced concrete T-shaped column-beam structure system has superiorities of both steel-reinforced structure and special-shaped column structure. This research focuses on steel-reinforced concrete T-shaped column-beam joint design and experimentally investigates seismic behaviors of the proposed joints. Pseudo-static tests are carried out on three steel-reinforced concrete T-shaped column-reinforced concrete beam joints and one reinforced concrete T-shaped column-reinforced concrete beam joint. The experiments were conducted under bidirectional low-cyclic reversed loading to simulate realistic loading conditions under earthquake. Hysteresis loops of all the specimens, including load–deflection, moment–rotation, and load–shear deformation loops, are plotted for the evaluation of seismic reaction. The working index, ductility coefficient, and equivalent viscous-damping coefficient are calculated for comparisons. Meanwhile, the ductility, capacity of energy dissipation, stiffness degradation, and the function of steel reinforcement in resisting shear force in the joint core area are intensively studied. Based on experimental results, this research analyzes shear-resistant capacity and the inner force transmission in these joints. It is found that the steel-reinforced concrete T-shaped column-reinforced concrete beam joint performs well under seismic conditions; moreover, shear-resistant capacity, ductility, and reliability are satisfactory. Conclusions derived from this research are useful for engineering practice.

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