EXPERIMENTAL VERTIFICATION FOR APPLYING NEUTRAL EQUILIBRIUM MECHANISM AS MULTIPLE VIRTUAL PIERS OF DISASTER RELIEF BRIDGE

2020 ◽  
Vol 7 (2) ◽  
Author(s):  
Ming-Hsiang Shih ◽  
Wen-Pei Sung ◽  
Martin Ghienne ◽  
Jun-Han Yao ◽  
Florian Beauval
Keyword(s):  
Moving Load ◽  
Construction Materials ◽  
Bending Moment ◽  
Control Device ◽  
Load Test ◽  
Displacement Sensor ◽  
Control Force ◽  
Ideal Behavior ◽  
Neutral Equilibrium ◽  
Force Mechanism

The purpose of this research is to develop an active-control mechanism and its control law, to reduce the deformation of the relief bridge and weight of construction materials and improve the effective span of the bridge. The counter-force (control force) mechanism, provided by Neutral Equilibrium Mechanism, NEM, is applied to exert a counter-force at the selected position of the bridge and maintain the deflection at this selected position to be zero. This proposed NEM is used as a counter-force mechanism, which is an automatic control device consisting of a pair of pressed steel strands, rotary cantilever arm mechanisms, a displacement sensor and a controller to form as a virtual pier. In this study, these proposed counter-force mechanisms are installed at the positions of 1/3 and 2/3 span of the bridge: the effective span is only 1/3 of the original span, the maximum bending moment and maximum deflection is only 1/9 and 1/27 of the original bridge, respectively. The experimental results display that the ideal behavior of this NEM can be fully achieved in the dynamic moving load test. The deflection and the bending moment of the bridge at the position of installing these NEMs are near zero. The goals of reducing deformation and improving the carrying capacity of the bridge are realized.

Study on Prediction Deflection of at the Girder Midspan of Large Tonnage Gantry Crane Rigid Legs

2014 ◽  
Vol 628 ◽  
pp. 214-218
Author(s):  
Da Peng Zhang ◽  
Wen Ming Cheng ◽  
Kun Cai
Keyword(s):  
Bending Moment ◽  
Moment Of Inertia ◽  
Load Test ◽  
Test Method ◽  
Gantry Crane ◽  
Deflection Curve ◽  
Concentrated Load ◽  
Small Load ◽  
Curve Equation

It is the most important inspection index of the deflection value for the girder of gantry crane under rated load in the overall test. In the overall test for large tonnage gantry crane which prepared for experimental weight is very difficult at the site, or even impossible perform test. In the text, it is deduced the girder deflection curve equation where considering the effects of the leg bending moment to the girder deflection When the concentrated load is applied to the position of L/2,L/3 and 2L/3 of the girder. The girder deflection value can be obtained under small load at the position of L/2,L/3 and 2L/3 of the girder and the actual moment of inertia of the girder and two side leg can be obtained. In this way, the deflection of the large tonnage gantry crane are predicted through the data of the three-position method in the small load test. Three-position small load test method provides a practical and effective method for the prediction of the girder deflection of large tonnage gantry structure.

Comparison of steel strength retention models for fire exposed concrete slabs

2021 ◽  
Author(s):  
Thomas Thienpont ◽  
Ruben Van Coile ◽  
Robby Caspeele ◽  
Wouter De Corte
Keyword(s):  
Reinforced Concrete ◽  
Construction Materials ◽  
Structural Response ◽  
Bending Moment ◽  
Concrete Slabs ◽  
Structural Behaviour ◽  
Moment Capacity ◽  
Retention Models ◽  
Reinforced Concrete Slabs ◽  
Strength Retention

<p>In structural fire engineering, there is a growing trend towards the use of performance based approaches to evaluate structural behaviour during or after a fire. Consequently, there is a need for an increased level of confidence in properties of construction materials used in these performance based approaches. Both steel and concrete have been experimentally observed to show a dispersal in the value of their respective structural strengths, at room temperature, but more significantly at high temperatures. In this paper the influence of three temperature dependent strength retention models for reinforcement steel on the bending moment capacity of simply supported reinforced concrete slabs exposed to a standardized fire is analysed. The results show that the structural response of reinforced concrete slabs strongly depends on the chosen probabilistic model, thus highlighting the importance of appropriate model selection.</p>

The Singular Function Method Based on the Moving Load Deformation of Suspension Bridge

2011 ◽  
Vol 403-408 ◽  
pp. 3059-3062
Author(s):  
Bang Sheng Xing ◽  
Xue Feng Wang
Keyword(s):  
Function Method ◽  
Moving Load ◽  
Bending Moment ◽  
Suspension Bridge ◽  
Simplified Model ◽  
Singular Function ◽  
Concentrated Load ◽  
Influence Line ◽  
Mathematical Equations ◽  
The Moment

This paper uses singular function method to analyze the deformation of simplified model of suspension bridge in the moving load, deduces the mathematical equations of the deflection and bending moment, analyzes the simplified model changes of mechanical deformation at different moving load position by using numerical analysis software mathcad,studies the most unfavorable load position and maximum absolute bending moment in a group of concentrated load, gets the results that the maximum absolute bending moment of suspension bridge section depends on the size of the load, mobile location and its distribution in a moving load. The moment influence line used by singular function is smooth segmentation functions. Researching findings provide theoretical basis for the design of suspension bridge.

Sensitivity Analysis of Continuous Curved Bridge under Different Curvature Radius

2014 ◽  
Vol 587-589 ◽  
pp. 1650-1654
Author(s):  
Mu Xin Luo ◽  
Jing Hong Gao
Keyword(s):  
Moving Load ◽  
Bending Moment ◽  
Element Model ◽  
Internal Force ◽  
Curvature Radius ◽  
Moving Loads ◽  
Dead Load ◽  
Actual Structure ◽  
Curved Bridge ◽  
The Dead

In the condition of the same span, to change the continuous curved bridge's curvature radius and under the dead load and moving load to compare how the internal force changes in different curvature radius. The finite element model is established to simulate the actual structure by Midas Civil. Results in a continuous curved bridge which main span of less than 60m, under the dead load, bending moment (-y) is unlikely to change, reinforced by a straight bridge can meet the requirements; under the moving loads, the curvature radius of the bending moment (-y) has little influence, should focus on increase in torque and bending moment (-z).

Dynamic Load Test and Data Analysis of Tiansheng Bridge

2014 ◽  
Vol 638-640 ◽  
pp. 1103-1106
Author(s):  
Hai Xia Ao ◽  
Yue Zhang ◽  
Yu Ping Yue
Keyword(s):  
Bearing Capacity ◽  
Moving Load ◽  
Strain Analysis ◽  
Time History ◽  
Load Level ◽  
Load Test ◽  
Dynamic Strain ◽  
Dynamic Load Test ◽  
Control Section ◽  
Road Grade

This test took dynamic strain detection method depending on time history curve of the dynamic deflection or the dynamic strain analysis of moving load in the control section to obtain impact factor. Using the method of environmental random vibration testing tested vibration response signals of L / 4 section of bridge test span , the cross section and 3 L / 4 section to identify the dynamic characteristics parameters of the overall vibration of Bridge, so that to determine current situation of application , assess the carrying capacity of bridge and test design load bearing capacity. According to the results of load test,the bearing capacity of Tiansheng bridge meets the requirements of "road - grade I" load level.

Vibration Control of an Offshore Wind Turbine

2021 ◽  
Author(s):  
Philip Alkhoury ◽  
Mourad Aït-Ahmed ◽  
Abdul-Hamid Soubra ◽  
Valentine Rey
Keyword(s):  
Optimal Control ◽  
Structural Control ◽  
Control Device ◽  
Offshore Wind ◽  
Structural Safety ◽  
Offshore Wind Turbine ◽  
Control Force ◽  
Linear Quadratic ◽  
Low Frequencies ◽  
System States

Abstract In order to reduce their cost, offshore wind turbines (OWTs) must have a powerful generator and a minimum overall weight. This has the consequence of making the OWT structure sensitive to dynamic excitations even at low frequencies. Indeed, modern multi-megawatt OWTs are composed of slender flexible and lightly damped components. The excessive vibrations of the OWT structure can impact the wind energy conversion to electricity, decrease the fatigue lifetime and even result in a total collapse of the structure when exposed to harsh environmental conditions. It is therefore important to reduce the unwanted vibrations of an OWT by implementing an appropriate control device that enhances its structural safety. Motivated by the potential of the structural control methods in suppressing OWTs vibration, this paper proposes the design of a controlled active tuned mass damper (ATMD) system to reduce the nacelle/tower out-of-plane vibration of a monopile-supported 10 MW DTU OWT subjected to combined wave and wind loads. Compared to previous works, the main originality of this paper is the inclusion of a state estimator, Linear Quadratic (LQ) observer, within an optimal control schema. The state observer aims to drastically reduce the number of required system states. Indeed, as some measurements are practically impossible, all system states cannot be obtained. In this study, a fully coupled multi-degree of freedom (MDOF) analytical model of a monopile-supported OWT developed in [4] is used for this purpose. The optimal control schema makes use of the robust LQR feedback controller to establish the ATMD actuator control force. The developed active control schema proved to efficiently reduce the nacelle/tower vibration.

Vibration Control of Serially Connected Isolation System Using Piezoelectric Actuator

2011 ◽  
Vol 250-253 ◽  
pp. 2112-2115
Author(s):  
Yan Hui Liu ◽  
Ping Tan ◽  
Fu Lin Zhou ◽  
Yong Feng Du ◽  
Wei Ming Yan
Keyword(s):  
Vibration Control ◽  
Piezoelectric Actuator ◽  
Performance Test ◽  
Control Experiment ◽  
Control Device ◽  
Shaking Table ◽  
Control Force ◽  
Isolation System ◽  
Control Efficiency ◽  
Fail Safe

This paper presents a bidirectional piezoelectric actuator, which can be used to vibration control of serially connected isolation System. Firstly, the performance test of this control device was processed. Then vibration control experiment of serially connected isolation system with this control device based on sweep sine shaking table was carried out. The experimental results show that this control device has stable mechanical properties, produces semi-active control force fast and has the outstanding control efficiency for serially connected isolation system. In addition, this control still has the satisfactory control efficiency when the piezoelectric actuator of this control is failed, which indicates the fail-safe function of this control.

scholarly journals On the Dynamic Response of a Beam to a Randomly Moving Load

1968 ◽  
Vol 35 (1) ◽  
pp. 1-6 ◽  
Author(s):  
J. K. Knowles
Keyword(s):  
Dynamic Response ◽  
Wiener Process ◽  
Stationary Process ◽  
Moving Load ◽  
Elastic Beam ◽  
Bending Moment ◽  
Concentrated Force ◽  
Stochastic Function

The problem considered is that of an infinitely long elastic beam subject to a moving concentrated force whose position is a stochastic function of time, X(t). The expected deflection and expected bending moment are analyzed, with special attention being given to the case of a stationary process X(t) and to the case in which X(t) is a Wiener process.

scholarly journals Dynamic Response of a Beam Subjected to Moving Load and Moving Mass Supported by Pasternak Foundation

2012 ◽  
Vol 19 (2) ◽  
pp. 205-220 ◽  
Author(s):  
Rajib Ul Alam Uzzal ◽  
Rama B. Bhat ◽  
Waiz Ahmed
Keyword(s):  
Differential Equation ◽  
Partial Differential Equation ◽  
Dynamic Response ◽  
Moving Load ◽  
Bending Moment ◽  
Dynamic Responses ◽  
Moving Mass ◽  
Pasternak Foundation ◽  
Partial Differential ◽  
Foundation Parameters

This paper presents the dynamic response of an Euler- Bernoulli beam supported on two-parameter Pasternak foundation subjected to moving load as well as moving mass. Modal analysis along with Fourier transform technique is employed to find the analytical solution of the governing partial differential equation. Shape functions are assumed to convert the partial differential equation into a series of ordinary differential equations. The dynamic responses of the beam in terms of normalized deflection and bending moment have been investigated for different velocity ratios under moving load and moving mass conditions. The effect of moving load velocity on dynamic deflection and bending moment responses of the beam have been investigated. The effect of foundation parameters such as, stiffness and shear modulus on dynamic deflection and bending moment responses have also been investigated for both moving load and moving mass at constant speeds. Numerical results obtained from the study are presented and discussed.

Numerical Analysis and Performance Test of Bidirectional Piezoelectric Control Device

2010 ◽  
Vol 163-167 ◽  
pp. 2977-2982
Author(s):  
Yan Hui Liu ◽  
Ping Tan ◽  
Fu Lin Zhou ◽  
Yong Feng Du ◽  
Wei Ming Yan
Keyword(s):  
Numerical Analysis ◽  
Performance Test ◽  
Mechanical Characteristics ◽  
Input Voltage ◽  
Control Device ◽  
Control Force ◽  
Friction Control ◽  
Variable Friction ◽  
Piezoelectric Control ◽  
And Performance

Based on the configuration and mechanical characteristics of piezoelectric actuator, the bidirectional piezoelectric variable friction control device which can produce control force in two orthogonal directions was designed and the relation equation of control force with input voltage for this control device was presented. Finally, one piezoelectric variable friction control device was manufactured and performance test of this control device was processed. The result of numerical analysis and experiment shows the bidirectional piezoelectric variable friction control device can produce semi-active control force fast, and the performance of this control device do not change when the frequency of input excitation varies and the control force of this control device has stable mechanical properties.

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