Simulation of Solutions to Excessive Vibration Problems of Pedestrian Footbridges

Footbriges are often prone to vibrations induced by pedestrian loading. They are long and slender and their weight is moderate. One of the classical and famous examples is the transverse vibrations encountered on the millennium bridge in London. Horizontal vibration problems have received considerable attention due to millennium bridge vibration problem, but potential problems relating to vertical vibrations are more common.Vibrations from pedestrian loads are mostly limited to vibration frequencies below 5Hz. Most pedestrian bridges have several vibration modes below the above mentioned frequency. Increasing the stiffness could be a remedy to this vibration problem. And for a slender structure, increasing the stiffness often implies a corresponding increas in mass of the structure, whereby the desired effect is notachieved…


1. Notation
2. Introduction
2.1 Background
2.2 Aim of the Work
2.3 Methodology
3. Structural Dynamics and Dynamic Load Induced By Pedestrians
3.1 Structural Dynamics
3.1.1 SDOF Model
3.1.2 Equation of Motion
3.1.3 MDOF
3.1.4 Modal Analysis
3.2 Dynamic Loads
3.2.1 Phenomenon of Synchronous Lateral and Vertical Vibration
3.3 Load Model
4. Structural Description and Dynamic Analysis of London Millennium Bridge
4.1 Structural Description
4.2 Finite Element model
4.3 SDOF Model of the Millennium Bridge
4.4 Dallard’s Load Model
4.4.1 Simulation of Dallard’s Load Model. Damping Requirement and Limiting Number of Pedestrian To Avoid Vibration
4.4.2 Nakamura’s Load Model Simulation of Nakamura´s Load Model: Comparison of Dallard’s and Nakamura’s load Model
5. Suggestions for Design Solutions
5.1 General Overview of Possible Solutions
5.2 Additional Damping
5.2.1 Viscous Damper
5.2.2 Tuned Mass Damper Effects of a Tuned Mass Damper on the Millennium Bridge.
6. Conclusion
7. Description of functions in the toolbox
8. References

Author: Ezeonwu, Emmanuel Chinedu and Ukoha, Christian Oji

Source: Blekinge Institute of Technology

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