Usage possibilities of EPS in the seismic protection of buildings and infrastructure

ΜUsing Geofoam EPS, you can achieve very effective seismic insulation in the construction of territorial support concrete elements, with significant cost reduction.

Important parameters: the thickness and the density of the Geofoam to be used, wall height, intensity and frequency of load.

The effectiveness of seismic insulation is increased with the thickness of the compressive insertion and with the reduction in the density of EPS. For studies, it is suggested to use Geofoam type EPS 100 (20kg/m3) and a value of seismic increase equal to 50% of the one that corresponds to a not-insulated wall (so: Ar=50%).

The required thickness of the compressive insertion depends more on the intensity of movement of the base and the height of the wall and less on the flexibility of the wall. For the design the following table can be used:

Thickness percentage of the inserted EPS 100 (20 Kgr/m3), tr (%), for the achievement of effectiveness of the seismic insulation Ar=50%

Research Group:

G. Athanasopoulos, Professor, Department of Civil Engineers, University of Patras,

V. Xenaki, CivilEngineer, Phd in Univeristy of Patras

Ch. Nikopoulou, Civil Engineer, MBA in Department of Civil Engineers, University of Patras,

V. Starhopoulou,Civil Engineer MBA in Department of Civil Engineers, University of Patras.

Example:

The research of the University of Patras gives us the way to calculation the thickness of Geofoam of Expanded Polystyrene (EPS) that should be used in every underground wall either if it is supporting the soil behind or if it is structural in a building, according to the seismic zone that it belongs, which can be seen in the previous picture, and the wall height.

The table above calculates the thickness of insertion as a percentage of the wall height, e.g.

City: Lamia (from picture) Seismic Zone: [II]

Wall height: 8,0 m (from table) 9,5%

Consequently the thickness should be 8,0 m X 9,5% = 0,76 m Geofoam EPS

With this thickness the reduction achieved in the force of the earthquake reaches 50%.

The results indicate that:

• The insulation ability is increased with the decrease in the density of EPS and leads to the use of as lighter EPS.
• The optimal effectiveness is achieved with the use of rectangular shapes, that have stable thickness throughout the height of the wall (taking into account the constructional facility).
• The insulation ability of EPS does not depend on the change of the rigidity of EPS and it is increased with the increase of the thickness, tr, of the insertion.
• It is possible to achieve values of effectiveness of seismic insulation Ar>50% for values of thickness tr>15%.
• The resulting relation between Ar - tr is not linear and therefore a relatively big thickness of insertions is required for the reduction of the seismic wave in percentages higher than 50%.