AASHTO R 33-20 pdf free download

AASHTO R 33-20 pdf free download.Calibrating the Reference Load Cell Used for Reference Calibrations for a Falling Weight Deflectometer.
3. TERMINOLOGY
Description of Terms SpecifIc to This Standard:
3.1 .1. reference load ce/I—custom-built calibration device used to calibrate the FWD load cell.
3.1.2. rejerence load cell swtein—system composed of the reference load cell and the associated data acquisition system. This system is used in the FWD load cell calibrations in R 32.
3.1 .3. data acquisition system—the signal conditioner, data acquisition board, data acquisition software, computer, and cabling. The reference load cell is connected to the signal conditioner.
3.1 .4. RefLCcal—the software required for data acquisition and data analysis for reference load cell calibration.2
3.1.5. WinFWDC’aI—the software required for data acquisition and data analysis for FWD calibration in R 32.
3.1.6. FWD load cell—device located on the loading mechanism of an FWD that measures the load response of the FWD system.
3.1.7. FWD load ce//final gain factor—calibration factor for the load sensor on the FWD determined by the R 32 FWD calibration procedure.
SUMMARY OF METHOD
The reference load cell system shall be calibrated using a universal testing machine or deadweight testing machine, herein referred to as testing machine.
4.2. The same equipment set used in R 32 shall be used in this procedure.
4.3. For each trial run, the load shall be applied slowly and continuously to a maximum of 100 kN (24,000 Ib). Readings shall be taken using the RefLCCal software during loading at each 5.0 kN (1,000 Ib) increment.
4.4. A minimum of three trials shall be carried out. The adjusted load data for three or more acceptable trials shall be combined using the RefLCC’al software.
4.5. The ReJLCCaI software will provide the statistically significant coefficients for a second- to fifth- order polynomial regression equation.
4.6. The coefficients shall be evaluated in accordance with the acceptance criteria in Section 9.2 of this procedure. If they are found to be acceptable, a calibration certificate shall be issued for the load cell.
4.7. The coefficients from the certificate should be entered into the WinFWDCaI data acquisition software used with the reference load cell system in R 32.
SIGNIFICANCE AND USE
In order to be confident in the FWD load cell final gain factor determined in the FWD load cell calibration procedure, the reference load cell must be calibrated against highly accurate, known loads.
APPARATUS
Testing Mac hine—The testing machine shall have a maximum capacity of at least 530 kN
(120,000 Ib). If a universal testing machine is used, it shall be static, hydraulic, or screw powered.
The high capacity of the testing machine assures that the test frame will be adequately rigid.
6.1.1. Servo-controlled, closed-loop testing systems of any manufacture shall not be used for calibrating the reference load cell.
6.1.2. The testing machine shall have a spherically seated bearing block that is adjusted so that it can easily align with the upper loading block.
6.1 .3. The testing machine shall have several load ranges. Use a range equal to or slightly more than the maximum load to which the reference load cell will be calibrated.
6.1.4. The universal testing machine shall have been calibrated in accordance with ASTM E4 at least 12 months prior to conducting this procedure. if a deadweight testing machine is used for calibration, the facility shall be accredited to iso 17025. The load measurement device(s) used to calibrate the testing machine shall be traceable to a national metrology institute (NMI).AASHTO R 33-20 pdf download.