Inverted And Hanging Pendulum Systems
Inverted and Hanging Pendulums are used for accurate and long-term monitoring of horizontal movements in large structures such as dams, bridges, nuclear power stations, towers and tall buildings.
The Hanging Pendulum comprises a Stainless Steel wire which is anchored at its top to the structure. A weight suspended from the lower end of the wire moves in an oil tank, the oil serving to dampen the oscillations of the wire. Measurements in both the X and Y axes are taken along the wire, using a portable optical readout or an automatic Charge Coupled Device (CCD) system.
For both the Inverted and Hanging Pendulums, vertical measurements (the Z axis) can optionally be taken by using a CCD system in conjunction with a reference mark on the wire.
The Inverted Pendulum uses identical measuring devices but the wire is anchored in stable ground beneath the structure and a float is fixed to the upper end of the wire which floats in a water tank, tensioning the wire and keeping it vertical.
- Greater measuring accuracy than precise geodectic surveying
- Manual or automatic readouts available
- Simple to use
- Long-term reliability
- Movements can be observed at frequent intervals without repeated and costly surveys
- Ideal for long-term use
- Can read X, Y and Z movement
Hanging Pendulum: The upper end of a Stainless Steel wire is anchored to the structure under observation. A weight suspended from the lower end of the wire keeps it under tension whilst being free to move in an oil tank.
Inverted Pendulum: The wire is anchored in stable ground beneath the structure. A float is fixed to the upper end of the wire which is then allowed to float free in a water tank whilst keeping tension in the wire.
Readings for both versions of the pendulum are treated in the same way. Displacements relative to the wire are measured using a portable optical readout or, for remote reading, an automatic CCD system. The reading arrays are corrected for temperature and an external digital display can be connected to the readout unit to display the X and Y (and Z, if used) positions in millimetres. The readout can be incorporated into almost any data acquisition system.
Hanging and Inverted Pendulum Systems are designed for accurate and long-term measurement of horizontal movements associated with the rotation or tilting of a structure.
Typical applications include determination of horizontal movement of:
- Dams and dam foundations
- Abutments, bridges, piers, towers
- Nuclear power stations
- Tall buildings