Shaking Tables


The Structural Dynamics Laboratory (UDinE) is part of the Earthquake Engineering and Structural Dynamics Unit, which is integrated in LNEC’s Structures Department, being equipped with the experimental infrastructures necessary for the development of R&D&I activities.

Additional information can be found at this laboratory's flyer.

Field of expertise

The main activity of UDinE consists of the characterization of the seismic behavior and vulnerability of large structures subjected to seismic actions of different intensities until imminent global collapse of structures or substructures.

Testing

LNEC-3D shaking table
The LNEC-3D shaking table, on which the models to be tested are placed and fixed, has the shape of a triangular prism with the following characteristics:
  • dimensions 4.6 × 5.6m2;
  • maximum capacity of 40 tons;
  • three independent orthogonal axes;
  • displacements controlled actively, passively restricted rotation (torsion bars);
  • frequency range of 0 to 40 Hz.

R&D&I experimental studies
Seismic testing, within the framework of the development of assisted reinforcement techniques and of the seismic rehabilitation of complete structures at scales close to real scale (1: 1.5 to 1: 2) or of substructures at full scale.

Seismic testing for the experimental evaluation and assisted development of both passive and semi-active systems intended to mitigate seismic stresses in structures.

Seismic qualification studies
Dynamic testing for the seismic qualification of equipment and components used by electricity producers and distributors.

Other services

UDinE conducts studies to assess the seismic vulnerability of important structural systems (e.g., buildings and bridges) using methodologies relying on objectives and on previously defined performance levels. These studies are based on the experimental determination of the dynamic behavior of structures and are essential in the implementation of reinforcement solutions to mitigate seismic vulnerability as regards one or more performance objectives established.



1D shake table

The 1D shake table, built in the early 1970s, consists of a steel platform body and a hydraulic circuit. It has the possibility of being used both as a horizontal and vertical shake table, but it is necessary to rotate the position of the hydraulic actuator.
The vertical platform is fixed to the frame of the horizontal platform, so that the same hydraulic actuator can be used. The restraining of the shake table rotations is ensured by a metal structure that supports the main frame through springs.

Main characteristics:
  • Useful dimensions (mxm): 3,0x2,0 (horizontal shake table), 2,45x1,45 (vertical shake table)
  • Drilling (mxm): 0,5x0,5
  • Specimen dead weight (kN): 60
  • Force (kN): 250
  • Displacements (mm): ±100
  • Velocity (cm/s): 21
  • Frequency range from 0 up to 25Hz
The shake table motions (horizontal and vertical) are analogically controlled by the proportional only internal loop (P) of the servo valves.