Background knowledge: basic bridge engineering and structural dynamics.

Equipment required: Personal laptop (some practical exercises will use open-source computer programs to analyse the response of bridges under wind actions).

This course focuses on the response of bridges subject to wind actions. The objectives are:

1.       To gain knowledge on basic wind engineering concepts such as the atmospheric boundary layer, bluff aerodynamics and vortex shedding.

2.       To describe the wind field around the structure based on current codes of practice and to understand the result of algorithms that generate three-dimensional turbulent wind velocity signals.

3.       To understand the methods currently used to define the aerodynamic effects in bridge structures, including wind tunnel testing and computational fluid dynamics.

4.       To use state-of-the-art models to describe quasi-static, buffeting, and aeroelastic actions in bridges.

5.       To learn how to assess the comfort and stability of bridges under wind actions, including vortex-induced vibrations, divergence and flutter.

6.       To understand the design concepts used in modern long-span bridges to resist wind actions.

Unit 1: Introduction to Wind Engineering (2 hours)

• Course presentation. Objectives. Content.
• Introduction to wind engineering. General concepts. Wind problems in civil engineering structures. Static and dynamic effects. Methods of study.
• Description of the proposed bridge case study to be considered in the course.

Unit 2: Atmospheric Wind (3 hours)

• Physical description of atmospheric wind. Characteristic dimensions of atmospheric wind. Global circulation, geostrophic wind, and gradient wind. Terrestrial boundary layer. Atmospheric turbulence. Local effects.
• Statistical description of the wind. Probability distributions. Extreme statistics (maximum speeds and dynamic pressures). Statistical description of turbulence.
• Regulations and standards in wind engineering. Wind models in calculation codes (Eurocode EN1991-1-4, ASCE/SEI 7-22, and AASHTO). Similarities, differences, and illustrative examples.
• Synthetic wind models. Shinozouka method. Skew angle effects.
• Exercise: study of simulated wind fields in the proposed bridge case study (practical session in class while students use their personal laptops).

Unit 3: Introduction to Aerodynamics (3 hours)

• Basic concepts of aerodynamics. Aerodynamics of blunt bodies. Reynolds and Strouhal numbers. Vortex shedding.
• Quasi-static loads on structures. Wind pressure. Aerodynamic interference and shielding phenomena.
• Aerodynamics of bridges. Wind problems in bridges. Wakes from pylons/barriers.
• Estimation of wind loads with calculation codes (Eurocode EN1991-1-4, ASCE/SEI 7-22, and AASHTO) (Practice).

Unit 4: Dynamic Phenomena in Structures and Bridges (3 hours)

• General response of a structure to atmospheric wind. Aeroelastic phenomena in structures, specifically in bridges.
• Aeroelastic instabilities. Vortex-induced vibrations (VIV). Torsional divergence. Galloping. Flutter. Buffeting.
• Aeroelastic phenomena in bridges: VIV and cable galloping.
• Analysis of aeroelastic phenomena with calculation codes (Eurocode EN1991-1-4, ASCE/SEI 7-22, and AASHTO). Scope and limitations. Illustrative examples.

Unit 5: Wind Tunnel Testing in Wind Engineering (3 hours)

• Introduction to experimental aerodynamics. Aerodynamic tunnels. Similarity laws. Simulation of the atmospheric boundary layer.
• Types of tests on civil engineering structures. Bridge tests.
• Specifications, requirements, scopes, and limitations of wind tunnel testing. Applicable standards.
• Interpretation and use of wind tunnel results. Examples and case studies.
• Technical visit to the wind tunnel facilities at the IDR institute (UPM campus).

Unit 6: Computational Fluid Dynamic Analysis in Bridge Engineering (4 hours)

• Introduction to computational fluid dynamics (theory delivered in class).

Unit 7: Dynamic Analysis of Bridges Subject to Turbulent Wind Actions (7 hours)

• Frequency-domain analysis and flutter derivatives (theory delivered in class).
• Time-domain analysis and buffeting theory (theory delivered in class).
• Linear unsteady models.
• Analysis of the dynamic response of the bridge case study subject to the wind simulated in Unit 2, and using the sectional properties obtained in Unit 6 (practical session in class while students use their personal laptops).

Unit 8: Assessment of Bridges Subject to Wind Actions (2 hours)

• Comfort assessment and vortex induced vibrations (theory delivered in class).
• Deck stability analysis. Calculation of the critical wind speeds for the bridge used in the case study during the course (practical session in class while students use their personal laptops).

Unit 9: Design of Long-span Bridges to Resist Wind Actions (3 hours)

• Deck and pylon cross-sections (theory delivered in class).
• Passive, semi-active, and active devices to control wind-induced vibrations.

The assessment of the students’ learning will be entirely based on coursework. This will be composed of a single piece of work covering the entire programme. The students will be asked to analyse and control the wind-induced response of a real bridge using the knowledge gained during course, combining analytical and numerical methods and making used of the software used during the practical sessions. The students will write a report and submit within a period of 30 days after the brief of the coursework is released, during the last session of the course.