Frequency modification of continuous beam bridge based on co-integration analysis considering the effect of temperature and humidity

2018 ◽  
Vol 18 (2) ◽  
pp. 376-389 ◽  
Author(s):  
Haoxiang He ◽  
Wei Wang ◽  
Xiaofu Zhang
Keyword(s):  
Environmental Factors ◽  
Effect Of Temperature ◽  
Integration Theory ◽  
Frequency Model ◽  
Modified Method ◽  
Continuous Beam Bridge ◽  
Bridge Model ◽  
Temperature And Humidity ◽  
Beam Bridge ◽  
Integration Analysis

The variation of the temperature and humidity significantly affects the modal parameters of the structure, and the effect and the quantitative statistics of single environmental factors such as temperature on the frequency of bridge are intensively studied, but the study on the mechanism and the effective model considering the comprehensive effect of multi-environmental factors is relatively rare. The principle and analysis method of co-integration is introduced, and the frequency-modified method based on co-integration is presented. Through the monitoring of a three-span concrete bridge model in the natural environment, the effective monitoring data are analyzed to establish a long-term equilibrium model about “frequency–temperature–humidity” based on co-integration theory. The experimental results indicate that the model has a better fitting ability and accuracy, and it is can be used to predict the variation trend of frequency. Based on the mathematical model of co-integration analysis, the modified frequency model considering multi-environmental factors is proposed, which can eliminate the comprehensive effect of temperature and humidity on frequency, and the variation of dynamic characteristics due to the internal causes of structure is revealed. The extracted sequence can provide effective information for further safety assessment and damage detection of bridge.

Experimental Study on the Effect of Temperature on Modal Frequencies of Bridges

2018 ◽  
Vol 18 (12) ◽  
pp. 1850155 ◽  
Author(s):  
Limin Sun ◽  
Yi Zhou ◽  
Zhihua Min
Keyword(s):  
Boundary Conditions ◽  
Freezing Point ◽  
Concrete Bridges ◽  
Effect Of Temperature ◽  
Steel Cable ◽  
Temperature Changes ◽  
Continuous Beam Bridge ◽  
Bridge Model ◽  
Increasing Temperature ◽  
Beam Bridge

This study investigates the relationship between the temperature and the modal frequencies of bridges through a series of model experiments using a concrete continuous beam bridge model and a steel cable-stayed bridge model in a controlled-temperature chamber. The experimental results show that, for a given boundary condition and in the absence of freezing, a change in temperature affects the structural frequencies of the bridge as it alters the elastic modulus of the bridge materials. The structural frequency tends to linearly decrease with increasing temperature and with the decrease in the frequency of steel bridges smaller than that of concrete bridges. For the particular case of wet concrete bridges, the temperature dependencies of modal frequencies vary dramatically near the freezing point, which is attributable to the freeze–thaw process of concrete pore water. The effect of air humidity on structural frequency is less significant than that of temperature when the boundary conditions remain unchanged. Furthermore, temperature changes may alter the boundary conditions of bridges, thereby affecting the structural frequencies.

scholarly journals Influence of Bearing on Pier Failure Considering the Separation Condition under Near-Fault Earthquake

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 692
Author(s):  
Wenjun An ◽  
Guquan Song
Keyword(s):  
Expansion Method ◽  
Transient Wave ◽  
Earthquake Excitation ◽  
Near Fault ◽  
Continuous Beam Bridge ◽  
Wave Function Expansion Method ◽  
Earthquake Action ◽  
Stiffness And Damping ◽  
Beam Bridge ◽  
Bending Failure

To study the influence of the near-fault vertical earthquake, the beam-spring-damper-pier model is used to simulate the double-span continuous beam bridge. The transient wave function expansion method and the indirect mode function method are used to calculate the seismic response of the bridge. The theoretical solutions of the contact force and displacement response of the bridge under vertical earthquake excitation near-fault are derived. By using piers with three different heights, the influence of vertical separation on pier-bending failure is analyzed reasonably. The results show that under the near-fault earthquake action, the split has a certain influence on the pier failure. Moreover, the stiffness and damping of the bearing have an influence on the pier failure, and the change of the maximum pier height has different effects. Therefore, for bridges of different sizes, it is of great significance to select the appropriate stiffness and damping bearings to reduce pier failure.

The Effect of Temperature and Humidity Levels in a Protective Mask on User Acceptability During Exercise

AIHAJ ◽  
1987 ◽  
Vol 48 (7) ◽  
pp. 639-645 ◽  
Author(s):  
R. NIELSEN ◽  
A.R. GWOSDOW ◽  
L.G. BERGLUND ◽  
A.B. DuBOIS
Keyword(s):  
Effect Of Temperature ◽  
Temperature And Humidity ◽  
User Acceptability ◽  
Protective Mask

Effect of temperature and humidity on reproductive performance of crossbred sows in Thailand

2006 ◽  
Vol 65 (3) ◽  
pp. 606-628 ◽  
Author(s):  
Annop Suriyasomboon ◽  
Nils Lundeheim ◽  
Annop Kunavongkrit ◽  
Stig Einarsson
Keyword(s):  
Reproductive Performance ◽  
Effect Of Temperature ◽  
Temperature And Humidity

A Study on the Restrainer for Isolated Bridge

2011 ◽  
Vol 243-249 ◽  
pp. 5208-5213
Author(s):  
Yong Feng Du ◽  
Xiao Yu Sun
Keyword(s):  
Lateral Displacement ◽  
Time History ◽  
Nonlinear Characteristics ◽  
Isolation System ◽  
Finite Element Software ◽  
Continuous Beam Bridge ◽  
History Analysis ◽  
Isolated Bridge ◽  
Isolated Bridges ◽  
Beam Bridge

As a result of adopting isolated bearings, it is inevitable to increase the lateral displacement of the superstructure and the chance of girder falling. However, the shear keys that just satisfies the structural design is far from meeting the requirements of displacement of isolated bridge restrictions. On account of this, given the nonlinear characteristics of bearings and the restrainer, the authors make the study on the "damping rubber with coupling collar" restrainer, and then establish isolation system model of continuous beam bridge with finite element software named Midas. Meanwhile, the effect of the restrainer on the dynamic response of isolated bridges is presented by time-history analysis, which reveals the great value in the application of limiting displacement of isolated bridge.

Effect of Temperature and Humidity on Nasal Flora of Mice

1955 ◽  
Vol 90 (2) ◽  
pp. 446-448 ◽  
Author(s):  
S. A. Mayyasi ◽  
J. M. Birkeland ◽  
M. C. Dodd
Keyword(s):  
Effect Of Temperature ◽  
Temperature And Humidity
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