Special Services

ES-Consult has since its establishment completed several tasks related to important civil and structural works and has also carried out many special assignments in the category of applied sience. A very important part of the activities of the firm has been assistance and technical consultances to building- and infrastructure owners.
Here follows descriptions of a series of ES-Consult's special services.



Aerodynamics and Aeroelasticity


The limits of the capacity of structures are constantly being verified and examined.
In this development the high strength of the materials of today is usually utilized, which enables us to design slender structures with long spans and great heights.

Wind acting on structures becomes more and more important in this connection in more than one way. Longer spans in themselves often cause the wind load to be the dominant load. In addition the dynamic characteristics of the structure become important for the response of the structure under the wind action.

The last-mentioned condition, determined by the aerodynamic behaviour of the structure, often sets the limit for the possible designs of the structure expressed by e.g. the span or the height. The structure may show an unacceptable performance - either by showing direct aerodynamic instability (flexural-torsional flutter as known from the legendary Tacoma bridge), or by giving comfort or fatigue problems. In the worst case phenomena causing inexpediencies or directly threatening safety may appear at low wind velocities.

ES-Consult has worked with these problems in detail in relation to projects and in research and development works.

Special Assignments

Certain aerodynamic phenomena can be encountered by special features of the design. An example is vibrations caused by vortex shedding. The phenomenon, which is known from chimneys and bridges, is very dependent on the natural damping of the structure. It is specially noticeable if the damping of the structure is small and if the structure is flexible, whereby the frequency of the vortex shedding may be locked in an interval to which the structure is sensitive. To overcome this the structure may be built with "appendages", which eliminate the damaging rhythmic vortex shedding, or the structure may be equipped with tuned mass dampers.
ES-Consult has worked on these problems in relation to various projects: The Great Belt Bridge, fatigue assessment of slender steel chimneys, etc.

Animation of oscillating cable


Staff members in ES-Consult have written several papers on the subject. A list of the papers is available.