A short seminar on "Virtual Laboratories for Advanced Structural Design" has been presented at Wit by Professor Santiago Hernandez, of the University of La Coruna in Spain.

Santiago is the Co-Chairman of the Structural Optimisation conference, organised by the Institute every two years, and has collaborated with WIT in many other initiatives and research activities. He is a member of the Board of Directors of WIT, and received the Eminent Scientist Medal in 1995 for his many, and important, contributions to the advancement of structural mechanics.

During his presentation Santiago discussed the two alternative approaches in science and technology, i.e. the experimental and computational methods. He then talked about the dynamic response of civil engineering structures, i.e. frequency and vibration modes, time history of displacements and time history of internal force or stresses. He initially compared the conventional computer representation of dynamic response with their experimental measurement. From this he progressed to propose a hybrid approach, using a mixed methodology of computational and experimental methods. He discussed the case of combining experimental results obtained in a wind tunnel with computer simulations, to investigate problems such as instability.

Santiago defined the term 'virtual environment' as a combination of the hybrid approach and advance computer graphics, using a structural model and visualisation tools. The objective is to produce accurate results of structural response in a user-friendly representation. Advanced visualisation models incorporate texture, colour, optical properties, etc. The structural analysis software used is based on state-of-the-art finite and boundary element codes, applying linear and non-linear dynamic analysis and incorporating, if necessary, the analysis of aeroelastic instabilities.

The seminar was illustrated with several interesting applications, such as a newly built bridge in Pontevedra; a pedestrian bridge over the river Lere, both in Galicia; the famous Tacoma Narrows bridge in the USA; and the Great Belt bridge in Denmark. The deformations of the bridges were shown on an outstanding video.

The conclusions of his talk were:

  • Evaluation of dynamic response of engineering structures usually require high-performance computers and parallelisation.
  • Conventional investigation is inefficient as a representation tool of dynamic properties of structures or time history responses.
  • An environment comprised of realistic visualisation models, advanced structural analysis and high-performance computers, can lead to an approach giving outputs similar to those obtained in actual experimental facilities.
  • Computer animations consist of a chain of static images at a rate of 25 frames per second. Therefore, computers with advanced graphic engines or multiprocessors can reduce, drastically, the amount of time required.
  • Virtual laboratories are well suited to visualise dynamic behaviours of civil engineering structures.

Santiago's presentation was followed by many questions and a lively exchange of opinions.