SpringVISCODAMPER

Large gas and diesel engines are used for many purposes - in trains and ships and for local power generation. In all cases, foundations for these engines must be both economical and effective. Elastic support of this equipment not only meets these requirements, but is currently the state of the art.

Around the world GERB springVISCODAMPER systems protect people, buildings and equipment from vibrations and structureborne noise. These systems allow diesel generators to be installed almost anywhere - whether in the third subbasement of a hotel in Seoul, on the thirtieth floor of a high-rise in Melbourne, as a power station on a remote Caribbean island or in a German nuclear power plant. For every machine foundation, local regulations must be considered. Which problems can arise?

During operation, some of the oscillating forces and moments generated by the engine are balanced internally; remaining forces and moments are transmitted into the foundation.

The frequency of these "residual" forces and moments is usually the same as or higher than the speed of the engine; however, it may also be half that speed. The engine and generator are arranged on a common foundation. With small equipment this usually consists of a steel frame. With larger generators a concrete or steel foundation is often provided to balance the dynamics of the engine with a corresponding mass and to channel dynamic and static forces safely into the subsoil. A heavy foundation alone provides this mass, but dynamic forces are still transmitted into the soil or substructure, the building and its surroundings.

Problems at this point can no longer be overlooked. Walls, support columns and roof of the diesel generator building can be excited by vibrations. A nearby machine in stand-by position can be damaged. Settlements can reach critical dimensions. Neighboring residential areas can experience disturbances.

While settlement problems can be solved with an expensive pile foundation, the transmission of disturbing dynamic forces can rarely be limited with conventional foundation methods.

Solving foundation problems after-the-fact is expensive. This usually necessitates considerable cost and, perhaps worst of all, a very long downtime for the machine.

The substructure is a critical part of the foundation design. In most cases this is the subsoil, other times it may be a floor or other type of construction. Not always are the static and less often are the dynamic properties known. While these properties can be estimated or assessed by an expert, risk remains and costs increase. A rigid massive foundation does not meet standards for vibration protection of the immediate vicinity nor of neighboring buildings. Therefore, GERB recommends dynamically uncoupling the machine foundation from the substructure by means of spring elements and VISCODAMPERS.

GERB Vibration Control Systems, Inc., 1950 Ohio Street, Lisle, IL 60532. Tel: 630-724-1660; Fax: 630-724-1664.