Super Long Span Bridge Aerodynamics
To define a standard in validating the software for the computation of the bridge response to the turbulent wind.
For long span bridges, the response to the turbulent wind is one of the major problems affecting the bridge design. The resulting vibrations have to be carefully considered for fatigue problems and life-time evaluation. Moreover, the safe design of the bridge must account for well-known types of instability, like flutter. Presently, there is no well-assessed method for computing bridge response to the turbulent wind.
In other fields of engineering, certified methods are available to deal with design and/or verification problems, such as the following examples:
a. software for computing the response of High Voltage Transmission lines to vortex-induced vibrations and subspan oscillations; this software is validated through benchmarks between different programs and against field measurements.
b. software for computing train dynamics to support homologation; the European Standard defines the procedure to validate the software through comparison between analytical and experimental results.
c. software for computing pantograph-catenary interaction; a European Standard to certify the software using a reference computation is available.
The activity of the Task Group should be organised according to the following steps:
1. Analysis of the different methods developed by researchers and designers involved in bridge design
2. Definition of guidelines identifying a procedure to obtain the data necessary for the computation, for instance:
a. Aerodynamic and aeroelastic parameters of the bridge that are to be identified
b. Structural parameters: modes of vibration and natural frequencies
c. Wind structure in the bridge site: design wind speed, wind turbulence index, etc
3. Definition of the computation procedure for:
a. Frequency domain or time domain
b. Fundamental issues of the computation method
c. Output results
Scope & Limitation
The fatigue design of long-span bridges usually depends on the results of numerical simulations that predict the structure response to turbulent wind. The reduction of the uncertainties of these numerical models would result in a more efficient and safety design and maintenance activity with direct impact on costs and scheduling.
As far as buffeting response of long-span bridges is concerned, a real estimation of the uncertainties is not easily predictable because of the complexity of the fluid-structure interaction problem and the lack of reliable benchmark data.
The main goal of this Task Group is the validation of numerical codes:
- The first step of the benchmark will be a comparison of the outputs of numerical simulations performed with different numerical codes used by the members.
- The second step of the benchmark will be a Numerical-Experimental comparison of the outputs of numerical simulations against wind tunnel tests results.
- The third step of the benchmark will be a Numerical-Experimental comparison of the outputs of numerical simulations against full scale tests results, if available.
Expected Project Output
- Guidelines and SEI reports/papers:
- Numerical vs numerical benchmark
- Numerical vs wind tunnel benchmark
- Organization of special sessions and workshops
- Special SEI issues
- Productions of reports which could be considered for publication as SED
Start Date: November 2016
Target Date of Completion: November 2022