Engineering Practice of Vibration Control for Long-Span Structures

2020 ◽  
pp. 647-676
Author(s):  
Aiqun Li
Keyword(s):  
Vibration Control ◽  
Engineering Practice ◽  
Long Span

Sublimation of composite ice and its influence on performance of ice shells

2021 ◽  
Vol 36 (1) ◽  
pp. 67-77
Author(s):  
Yue Wu ◽  
Junkai Huang ◽  
Jiafeng Chen
Keyword(s):  
Numerical Simulation ◽  
Shell Structure ◽  
Composite Shell ◽  
Engineering Practice ◽  
Sublimation Rate ◽  
Long Span ◽  
Static Performance ◽  
New Type ◽  
Ice Sublimation ◽  
Composite Shell Structure

The long-span ice composite shell structure is a new type of ice and snow structure developed in recent years. The engineering practice of ice composite shell shows that sublimation is one of the important reasons for its damage and even collapse. In this paper, we firstly supplemented the existing H-K equation and obtained the revised ice sublimation equation through indoor evaporative plate experiment considering the influence of admixtures and wind speed. Afterwards, combining the simulations of solar radiation and CFD, the numerical simulation of sublimation distribution on the surface of were realized by programming in Grasshopper platform. During sublimation, the thickness of the ice composite shell decreases by 0.38 mm every 10 days and the sublimation rate on the sunny side was 1.7 times that on the shady side. Finally, the static performance and stability of the sublimated ice composite spherical shell were analyzed. After 70 days of sublimation, the thickness of the ice composite shell structure becomes thinner and uneven, which leads its sensitivity to external load increases.

scholarly journals Serviceability Assessment Method of Stay Cables with Vibration Control Using First-Passage Probability

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Seunghoo Jeong ◽  
Young-Joo Lee ◽  
Sung-Han Sim
Keyword(s):  
Vibration Control ◽  
Control Method ◽  
Principal Component ◽  
Assessment Method ◽  
Stay Cable ◽  
First Passage ◽  
Long Span Bridges ◽  
Long Span ◽  
Stay Cables ◽  
Cable Stayed Bridges

As the construction of long-span bridges such as cable-stayed bridges increases worldwide, maintaining bridge serviceability and operability has become an important issue in civil engineering. The stay cable is a principal component of cable-stayed bridges and is generally lightly damped and intrinsically vulnerable to vibration. Excessive vibrations in stay cables can potentially cause long-term fatigue accumulation and serviceability issues. Previous studies have mainly focused on the mitigation of cable vibration within an acceptable operational level, while little attention has been paid to the quantitative assessment of serviceability enhancement provided by vibration control. This study accordingly proposed and evaluated a serviceability assessment method for stay cables equipped with vibration control. Cable serviceability failure was defined according to the range of acceptable cable responses provided in most bridge design codes. The cable serviceability failure probability was then determined by means of the first-passage problem using VanMarcke’s approximation. The proposed approach effectively allows the probability of serviceability failure to be calculated depending on the properties of any installed vibration control method. To demonstrate the proposed method, the stay cables of the Second Jindo Bridge in South Korea were evaluated and the analysis results accurately reflected cable behavior during a known wind event and show that the appropriate selection of vibration control method and properties can effectively reduce the probability of serviceability failure.

Vibration Control of Long-Span Beams: Experimental and Analytical Study of Beam Structures Incorporated with Connection Dampers

2004 ◽  
Vol 10 (5) ◽  
pp. 707-730 ◽  
Author(s):  
X. M. Tan ◽  
J. M. Ko
Keyword(s):  
Fractional Derivative ◽  
Vibration Control ◽  
Analytical Method ◽  
Analytical Study ◽  
Beam Structures ◽  
Viscoelastic Dampers ◽  
Long Span ◽  
Parametric Studies ◽  
Vertical Vibrations ◽  
Structural Behaviors

In order to reduce the vertical vibrations of long-span beam structures subjected to human activities or machinery running, a type of beam-column connection incorporated with viscoelastic dampers is designed and the effectiveness in vibration control is proved experimentally. An analytical method implemented with a fractional derivative model for structures with such damping devices is then proposed. By comparing analytical results with test data, the method is verified to be able to predict structural behaviors very well. Based on the parametric studies being carried out, useful guidelines are achieved for design of beam structures with connection dampers.

Vertical and Horizontal Seismic Response Analyses of Long-Span and Single-Layer Spherical Lattice Shell Structure

2014 ◽  
Vol 602-605 ◽  
pp. 602-605
Author(s):  
Jin Sheng He ◽  
She Liang Wang
Keyword(s):  
Vibration Control ◽  
Shell Structure ◽  
Response Spectrum ◽  
Single Layer ◽  
Internal Force ◽  
Seismic Load ◽  
Seismic Responses ◽  
Long Span ◽  
Current Design ◽  
Lattice Shell

The dynamic characteristics of 80 m single-layer spherical lattice shell structure are analyzed to control its vibration under seismic load. Through the response spectrum curve of current design specification, the analyses for the vertical and horizontal seismic responses of the single-layer spherical lattice shell structure are made by CQC, and the displacement response of the nodes and internal force of the rods unit are calculated respectively. The calculation results show that the vertical and horizontal seismic responses of the long-span lattice shell structure are in great difference, and should be performed in vibration control at the same time, which could provide certain references for the seismic design and vibration control of single-layer spherical lattice shell structure.

scholarly journals Feedforward and Feedback Vibration Control and Algorithm Design for Cable-Bridge Structure Nonlinear Systems

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Yan-Jun Liang ◽  
Shi-Liang Wu ◽  
De-Xin Gao ◽  
Xiao-Rong Xue
Keyword(s):  
Vibration Control ◽  
Algorithm Design ◽  
Coupled Systems ◽  
Superposition Method ◽  
Bridge Structure ◽  
Control Approach ◽  
Long Span ◽  
Control Devices ◽  
Wind Induced Vibration ◽  
Optimal Control Approach

Technique of feedforward and feedback optimal vibration control and simulation for long-span cable-bridge coupled systems is developed. Buffeting loading systems of long-span cable-bridge structure are constructed by weighted amplitude wave superposition method. Nonlinear model of cable-bridge coupled vibration control system is established and the corresponding system of state space form is described. In order to reduce buffeting loading influence of the wind-induced vibration for the structure and improve the robust performance of the vibration control, based on semiactive vibration control devices and optimal control approach, a feedforward and feedback optimal vibration controller is designed, and an algorithm is presented for the vibration controller. Numerical simulation results are presented to illustrate the effectiveness of the proposed technique.

scholarly journals Study on Control Technology for Working Faces Passing through Long-Span Abandoned Roadways

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Zhenghe Liu ◽  
Hailong Ye ◽  
Lusheng Yang ◽  
Shaohua Wang ◽  
Junwen Zhang ◽  
...  
Keyword(s):  
Plastic Zone ◽  
Impact Load ◽  
Great Influence ◽  
Coal Pillar ◽  
Field Testing ◽  
Engineering Practice ◽  
Hydraulic Support ◽  
Long Span ◽  
Working Face ◽  
Working Resistance

The width of an abandoned roadway has a great influence on the roof stability of the working face. According to the coal seam conditions of the 30106 working face in the Sanyuan Shiku mine, the advance of a working face through an abandoned roadway was studied by using theoretical analysis, similar material simulation, numerical simulation, and field testing to determine the law of stope roof fracture migration, the stress distribution characteristics, and the variation in support resistance. Several conclusions are drawn: (1) The roof of the overlying strata is fractured at the edge of the abandoned roadway in front of the coal pillar and rotates downward due to the run-through of the plastic zone between the working face and abandoned roadway. (2) The hydraulic support working resistance gradually increases with decreasing coal pillar width between the working face and abandoned roadway, and the working resistance of the support tends to peak when the plastic zone extends to the coal, resulting in 3~4 times the normal recovery. Leakage occurred in front of the support in the caving zone. (3) The analysis of the relationship between the support and surrounding rock with the mechanical model for calculating the support load allows the derivation of the support working resistance formula for a working face passing through an abandoned roadway. (4) When the working face is excavated to expose the abandoned roadway, the shrinkage of the front column of the hydraulic support is significantly greater than that of the back column, and the stability is greatly reduced. This problem can be effectively solved when the uniaxial compressive strength of the backfill ≥2 MPa. (5) The engineering practice showed that the danger of leakage and roof fracture impact load was eliminated with the mining pressure reduction after reinforcement measures were taken in the abandoned roadway. The working face passed the abandoned roadway safely, providing the theoretical basis and guidance for coal remining under similar conditions.

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