European Laboratory for Structural Assessment

European Laboratory for Structural Assessment

The kernel of the European Laboratory for Structural Assessment (ELSA) is the Reaction Wall. It consists of a re-inforced concrete vertical wall and a horizontal floor rigidly connected together to test the vulnerability of buildings to earthquakes and other hazards.

By means of computer controlled hydraulic actuators it is possible to expose full scale structures to loads of dynamic strong forces and control the resulting movements with high precision. The wall and the floor are designed to resist the forces, typically several MN, which are necessary to deform and seriously damage the full-scale test models of structures.

The ELSA Reaction Wall is the largest facility of its kind in Europe and one of the largest in the World - only exceeded in Japan.

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The Pseudo-Dynamic Test (PSD) technique

In addition to static and cyclic tests on large structures and components, the facility is equipped for the so-called pseudo-dynamic test (PSD) technique. The PSD enables the simulation of earthquake loading of full-scale buildings.

The structure to be tested is fixed to the horizontal floor.  Once the ‘test structure’ is in place, the force that an earthquake would generate is applied through hydraulic jacks acting between the structure and the vertical wall, subjecting the structure to loads equivalent to those caused by the earthquake . For the purposes of testing the ‘earthquake’ experiment takes place in extreme slow motion, one to two hours rather than the 10 to 30 second duration of a real earthquake,  allowing progressive damage and structural deformations to be accurately observed and recorded.


International collaboration

The ELSA facility is used within the framework of European Union wide integrated research programmes and is also available to external customers for performing demonstration and qualification tests on large-scale prototypes and/or validation innovative constructions. This offers a major opportunity to the European construction industry to enhance its competitive position in world-wide markets, especially in countries with high seismic risk.



The Load Capacities

Reaction Wall:

  • Bending Moment 200 MNm
  • Base Shear 20 MN

Reaction Floor:

  • Bending Moment 240 MNm


  • Axial Force 500 kN

The Hydraulic System

Flow: 25 l/sec
Pressure: 210 bar


  • Load: 500 kN
  • Stroke 1:± 0.25 m
  • Stroke 2: ± 0.50 m


Science Areas