Electronic instruments for data acquisition

  In the field load test, collecting and recording the data were carried out by sensors and data loggers. Now, the instruments are kept in Evaluation and Condition Monitoring laboratory of the Central Bureau of Technical Track and Structures. It is essential to note that these instruments are also applied for condition monitoring of both road and railway tracks and bridges and of other structures.

  This center, being equipped with the following instruments, has made a sound investment on conducting field condition monitoring of all civil structures in general and railway track and bridges, in particular.

  1. a static 96-channel data logger with a sampling frequency of 20 Hz

  2. a dynamic 48-channel data logger with a sampling frequency of 2 KHz

  3. 40 LVDTs (5-100 mm)

  4. 10 DCDTs (25mm)

  5. 62 piezo-resistance accelerometers (2, 5, and 10 g)

  6. Strain gauge (concrete 25-250 mm and steel 3-20 mm)

  7. 12 loud-cells (1, 2, & 5 tons: tension and 2, 5, 10 tons: compressive)

  In line with this investment, a significant number of projects have been carried out in Iran, among which are: concrete arch railway bridge load test, Tale Zang Railway Bridge load test, railway load test to investigate the speed and optimal super-elevation of trains passing a curve, and railway load test to study the degradation effect on the mechanical and geometric parameters of the structure and ground, and, finally, Ghal’e Morghi load test.

  In the following, the picture and application of some of the above-mentioned instruments are illustrated.

  Picture 1. Card converting signals from analogue to digital installed on data recording computer

  Picture 2. CHANNEL CONNECTION BLOCK

  Application: Making connection between ADC and the combined medol of accelerometers and LVDT sensors

  48 Picture 3. CHANNEL CONNECTION BLOCK

  Application: Making connection between ADC and Anti-Aliasing Filter

  Picture 4. Anti-Aliasing Filter

  Application: Removing frequencies above 1000 Hz

  Picture 5. Strain gauge Amplifier Module

  Application: Amplifying weak signals (mv) and converting them into strong signals of LVDT sensors

  Picture. BNC BREAKOUT BOX

  Application: Making connection between AMPLIFIER and CONNECTION BLOCK

  PICTURE 7. COMBINED MODULE

  APPLICATION: Providing for accelerators, LVDT, and data logger connection

  PICTURE 8. STRAIN GAUGE WIRING IN BOX

  APPLICATION: Connecting LVDT wires to the amplifier and creating Watson Bridge

  PICTURE 9. Calibration box

  APPLICATION: Activating the calibration resistance of amplifier cards

  PICTURE 10. STRAIN GAUGE AMPLIFIER CARDS

  APPLICATION: Each card can amplify two channels and can be converted into DCDT and Load cell signal amplifier.

  PICTURE 11. EARTH TERMINATOR

  APPLICATION: Removing the electrical signals not connected to sensors

  PICTURE 12. Data Logging PC

  APPLICATION: Recording the received data from ADC installed on computer

  PICTURE 13. The connection box of strain gauge wires, amplifier, LVDT, and accelerometer in test site