Wind induced instabilities such as flutter and divergence are of primary concern for the wind-resistant design of a long-span bridge. The increase of the critical wind speed of a suspension bridge is to be obtained by passive aerodynamic control systems. The systems utilize additional control surfaces attached to the bridge girder. The bridge movement is coupled with rotational motion of the surfaces. Bridge vibrations cause rotations of the surfaces, which in turn, generate aerodynamic forces used for the enhancement of the aerodynamic stability.
The aim of the study is derivation of the mathematical model of the proposed passive aerodynamic control systems and estimation of their effectiveness in an improvement of the stability of long-span bridges exposed to the action of winds.
The FEM models of a full three dimensional bridge equipped with a passive aerodynamic control system are derived. The unsteady aerodynamic forces generated on the bridge deck and control surfaces are modeled in time domain by rational function approximation. The mathematical models are verified by wind tunnel experiments conducted on sections of the control systems.
Parametric study provides configurations of the most effective control systems. The dynamic analysis of the selected systems shows that the passive aerodynamic control systems can effectively increase critical wind speed of the bridge to the required level.
Spis treści:
Notation
1. Introduction
1.1. Wind loads on bridges
1.2. Methods of analysis of aeroelastic response of bridges
1.2.1. Wind tunnel experiments
1.2.2. Analytical methods
1.3. Suppression of wind induced vibration of long span bridges
1.4. Aim and scope of study
2. Study on sectional models of passive aerodynamic control systems
2.1. Bridge-surfaces control system
2.1.1. Mathematical model of aerodynamic forces
2.1.2. Equation of motion of bridge-surfaces control system
2.1.3. Numerical simulations
2.1.3.1. Uncontrolled bridge
2.1.3.2. Control system 1
2.1.3.3. Control system 2
2.2. Bridge-flaps control system
2.2.1. Mathematical model of aerodynamic forces
2.2.2. Equation of motion of bridge-flaps control system
2.2.3. Numerical simulations
2.2.3.1. Uncontrolled bridge
2.2.3.2. Control system 1
2.2.3.3. Control system 2
2.3. Conclusions
3. Wind tunnel experiments on sectional models of aerodynamic control systems
3.1. Experiment on bridge-surfaces control system
3.1.1. Description of experiment
3.1.2. Experimental results
3.2. Experiment on bridge-flaps control system
3.2.1. Description of experiment
3.2.2. Experimental results
3.3. Conclusions
4. Study on three dimensional FEM models of control systems
4.1. Long span suspension bridge
4.1.1. FEM model of the bridge
4.1.2. Numerical simulations
4.2. Bridge-surfaces control system
4.2.1. FEM model
4.2.2. Numerical simulations
4.2.2.1. Control system 1
4.2.2.2. Control system 2
4.3. Bridge-flaps control system
4.3.1. FEM model
4.3.2. Numerical simulations
4.3.2.1. Control system 1
4.3.2.2. Control system 2
4.4. Conclusions
5. Concluding Remarks Acknowledgments
References
Appendix A
Appendix B
Appendix C
Abstract in English
Abstract in Polish
