scholarly journals Monitoring of Liquid Viscosity for Viscous Dampers through a Wireless Impedance Measurement System

2021 ◽  
Vol 12 (1) ◽  
pp. 189
Author(s):  
Sihui Jia ◽  
Mingzhang Luo
Keyword(s):  
Viscosity Index ◽  
Impedance Measurement ◽  
Piezoelectric Sensor ◽  
Measurement Technology ◽  
Fluid Viscosity ◽  
Viscous Damper ◽  
Viscous Dampers ◽  
Monitoring Method ◽  
High Rise ◽  
Piezoelectric Impedance

Viscous dampers are a type of seismic damping equipment widely used in high-rise buildings and bridges. However, the viscosity of the damping fluid inside the viscous damper will change over time during its use, which significantly reduces the seismic performance of the viscous damper. Hence, it is necessary to monitor the viscosity of the fluid inside the damper over its service life. In this paper, a damping fluid viscosity monitoring method based on wireless impedance measurement technology is proposed. A piezoelectric sensor is installed in a damper cylinder specimen, and the viscosity of the damping fluid is determined by measuring the piezoelectric impedance value of the sensor. In this study, 10 samples of damping fluids with different viscosities are tested. In order to quantitatively correlate damping fluid viscosity and electrical impedance, a viscosity index (VI) based on the root mean square deviation (RMSD) is proposed. The experimental results show that the variation of the real part in the impedance signal can qualitatively determine the damping fluid viscosity while the proposed VI can effectively and quantitatively identify the damping fluid viscosity.

Seismic Reduction and Control Analysis of Hybrid Structure with Viscous Dampers under Strong Earthquake

2014 ◽  
Vol 580-583 ◽  
pp. 1633-1636 ◽  
Author(s):  
Sen Qiu ◽  
Shu Cheng Deng ◽  
Zhao Quan Zhu
Keyword(s):  
Strong Earthquake ◽  
Lateral Displacement ◽  
Hybrid Structure ◽  
Earthquake Ground Motion ◽  
Control Analysis ◽  
Viscous Damper ◽  
Viscous Dampers ◽  
Maximum Value ◽  
Story Drift ◽  
And Control

This article focuses on the effect of viscous damper on seismic performance of steel-concrete hybrid structure under strong earthquake. The result shows that viscous damper has effect on seismic reduction and control. The story lateral displacement, story drift rotation and energy dissipation-seismic can be reduced effectively by viscous dampers. The maximum value of vibration-reduction ratio is 36.0%, 67.9%, 36.9%. It is different effect on seismic reduction by different earthquake ground motion. Response of earthquake amplifies under Pasadena earthquake wave than the others.

scholarly journals Effect of Adhesive Debonding on the Performance of Piezoelectric Sensors in Structural Health Monitoring Systems

Sensors ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 5070 ◽  
Author(s):  
Liu ◽  
Xu ◽  
Li ◽  
Wang ◽  
Zhang
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Research Work ◽  
Piezoelectric Sensor ◽  
Systematic Investigation ◽  
Monitoring Method ◽  
Structural Health ◽  
Negative Effect ◽  
Inherent Frequency ◽  
Slow Rise

Piezoelectric (PZT) ceramic elements are often subjected to complex loads during in- service lifetime in structural health monitoring (SHM) systems, and debonding of both excitation actuators and receiving sensors have a negative effect on the monitoring signals. A first systematic investigation of debonding behaviors by considering actuators and sensors simultaneously was performed in this paper. The debonding areas of actuators were set in different percentage range from 0% to 70%, and sensors in 0%, 20%, 40% and 60%. The signal-based monitoring method was used to extract the characteristic parameters of both the amplitudes and phases of received signals. Experimental results revealed that as the debonding areas of the actuators increase, the normalized amplitude appears a quick decrease before 35% debonding area of actuators and then a slow rise until 60% of debonding reached. This may be explained that the 35% debonding turning point correspond to the coincidence of the excitation frequencies of peripheral actuators with the inherent frequency of the central piezoelectric sensor, and the 60% be the result of the maximum ability of piezoelectric sensor. The degrees of debonding of actuators and sensors also have significant influence on the phase angle offset, with large debonding of actuators increases the phase offset sharply. The research work may provide useful information for practical monitoring of SHM systems.

scholarly journals Retrofit Existing Frame Structures to Increase Their Economy and Sustainability in High Seismic Hazard Regions

2019 ◽  
Vol 9 (24) ◽  
pp. 5486 ◽  
Author(s):  
Shuang Li ◽  
Jintao Zhang
Keyword(s):  
Optimum Design ◽  
Computational Cost ◽  
Time History ◽  
Economic Benefits ◽  
Frame Structure ◽  
Viscous Damper ◽  
Viscous Dampers ◽  
Frame Model ◽  
Rare Earthquake ◽  
Original Frame

The study proposes a retrofitting method with an optimum design of viscous dampers in order to improve the structural resistant capacity to earthquakes. The retrofitting method firstly uses a 2D frame model and places the viscous dampers in the structure to satisfy the performance requirements under code-specific design earthquake intensities and then performs an optimum design to increase the structural collapse-resistant capacity. The failure pattern analysis and fragility analysis show that the optimum design leads to better performance than the original frame structure. For regular structures, it is demonstrated that the optimum pattern of viscous damper placement obtained from a 2D frame model can be directly used in the retrofitting of the 3D frame model. The economic loss and repair time analyses are conducted for the retrofitted frame structure under different earthquake intensities, including the frequent earthquake, the occasional earthquake, and the rare earthquake. Although the proposed method is based on time-history analyses, it seems that the computational cost is acceptable because the 2D frame model is adopted to determine the optimum pattern of viscous damper placement; meanwhile, the owner can clearly know the economic benefits of the retrofitting under different earthquake intensities. The retrofitting also causes the frame to have reduced environmental problems (such as carbon emission) compared to the original frame in the repair process after a rare earthquake happens.

The Applied Research of Safety Monitoring and Forecasting Technology in the Foundation Pit Supporting Construction

2013 ◽  
Vol 443 ◽  
pp. 214-217
Author(s):  
Zhen Xi Yu
Keyword(s):  
Applied Research ◽  
Technical Process ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Monitoring Method ◽  
Engineering Construction ◽  
Deep Foundation Pit ◽  
High Rise ◽  
Monitoring And Forecasting ◽  
Control Accuracy

With the scale development of our high-rise buildings, together with the development and enhancing of monitoring technology of deep foundation pit supporting construction. Control accuracy is the main part for monitoring technical process in deep foundation pit supporting construction, the requirement of monitoring is higher and higher than before, relevant monitoring method, frock and tools, earthwork type of shipping and downriver way in engineering construction will develop in revolutionary way. In view of above mentioned, this paper try to do researching on monitoring technical process in deep foundation pit supporting construction in our country, hope to supply reference for counterparts.

Detection of Contact-Type Damages by Utilizing Nonlinear Piezoelectric Impedance Modulation of Self-Excited Structures

2013 ◽  
Author(s):  
Arata Masuda ◽  
Yuya Ogawa ◽  
Akira Sone
Keyword(s):  
Damage Detection ◽  
Wave Field ◽  
High Frequency ◽  
Detection Method ◽  
Piezoelectric Sensor ◽  
Frequency Wave ◽  
Contact Type ◽  
Impedance Modulation ◽  
Excited Oscillation ◽  
Piezoelectric Impedance

This paper presents an improvement of a nonlinear piezoelectric impedance modulation (NPIM)-based damage detection method, a damage-sensitive, baseline-free structural health monitoring technique proposed by the authors, by introducing self-excited oscillation. The NPIM-based damage detection utilizes the modulation of high-frequency wave field of structures caused by the contact acoustic nonlinearity at the damaged part. In this study, the high-frequency wave field is induced as a self-excited oscillation of the structure by positively feed-backing the strain signal measured by a surface-bonded piezoelectric sensor, followed by a phase-shift in 90 degrees and a nonlinear element consisting of a saturation element and a negative linear gain. The induced self-excitation can have multiple stable limit cycles at certain eigenmode frequencies, and one can switch among them by inputting an auxiliary excitation signal into the feedback loop. The current flowing through the piezoelectric sensor is measured to detect its modulation due to the stiffness fluctuation due to the existence of the contact-type damage. Experiments using a specimen with a simulated damage are conducted to examine the performance of the self-excitation circuit and its applicability to the NPIM-based damage detection method.

Shake Table Studies on Viscous Dampers in Seismic Control of a Single-Tower Cable-Stayed Bridge Model under Near-Field Ground Motions

2018 ◽  
Vol 12 (05) ◽  
pp. 1850011 ◽  
Author(s):  
Jiang Yi ◽  
Jianzhong Li ◽  
Zhongguo Guan
Keyword(s):  
Ground Motions ◽  
Near Field ◽  
Far Field ◽  
Viscous Damper ◽  
Viscous Dampers ◽  
Damping Force ◽  
Seismic Control ◽  
Cable Stayed Bridge ◽  
Bridge Model ◽  
Cable Stayed Bridges

To investigate the effectiveness of viscous damper on seismic control of single-tower cable-stayed bridges subjected to near-field ground motions, a 1/20-scale full cable-stayed bridge model was designed, constructed and tested on shake tables. A typical far-field ground motion and a near-field one were used to excite the bridge model from low to high intensity. The seismic responses of the bridge model with and without viscous dampers were analyzed and compared. Both numerical and test results revealed that viscous dampers are quite effective in controlling deck displacement of cable-stayed bridges subjected to near-field ground motions. However, due to near-field effects, viscous damper dissipated most energy through one large hysteresis loop, extensively increasing the deformation and damping force demand of the damper. Further study based on numerical analysis reveals that to optimize deck displacement of cable-stayed bridges during an earthquake, a viscous damper with relatively larger damping coefficient should be introduced under near-field ground motions than far-field ones.

Dynamical shakedown analysis of high-rise tower structure

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Guichen Zhang ◽  
Hongtao Zhang ◽  
Heng Peng ◽  
Yinghua Liu
Keyword(s):  
Free Vibration ◽  
Cantilever Beam ◽  
Dynamic Load ◽  
External Load ◽  
Load Capacity ◽  
Viscous Damper ◽  
Shakedown Analysis ◽  
Content Type ◽  
High Rise ◽  
Tower Structure

Purpose High-rise tower structures supported by side frame structure and viscous damper in chemical industry can produce plasticity under dynamic loads, such as wind and earthquake, which will heavily influence the long-term safety operation. This paper aims to systematically study the optimization design of these structures by free vibration and dynamic shakedown analysis. Design/methodology/approach The transfer matrix method and Euler–Bernoulli beam vibration are used to study the free vibration characteristic of the simplified high-rise tower structure. Then the extended stress compensation method is used to construct the self-equilibrated stress by using the dynamic load vertexes and the lower bound dynamic shakedown analysis for the structure with viscous damper. Using the proposed method, comprehensive parametric studies and optimization are performed to examine the shakedown load of high-rise tower with various supported conditions. Findings The numerical results show that the supported frame stiffness, attached damper or spring parameters influence the free vibration and shakedown characters of high-rise tower very much. The dynamic shakedown load is lowered down quickly with external load frequency increasing to the fundamental natural frequency of the structure under spring supported condition, while changed little with the damping connection. The optimized location and parameter of support are obtained under dynamical excitations. Research limitations/implications In this study, the high-rise tower structure is simplified as a cantilever beam supported by a short cantilever beam and a damper under repeated dynamic load, and linear elasticity for solid is assumed for free vibration analysis. The current analysis does not account for effects such as large deformation, stochastic external load and nonlinear vibration conditions which will inevitably be encountered and affect the load capacity. Originality/value This study provides a comprehensive method for the dynamical optimization of high-rise tower structure by combining free vibration and shakedown analysis.

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