AASHTO R8-96 pdf free download

AASHTO R8-96 pdf free download.Evaluation of Transportation-RelatedI Earth borne Vibrations.
The sensitivity range of the instrument should be selected so that recording is initiated below the intensity of the objectionable vibrations and extends above the highest expected intensity. It may be necessary to estimate or predetermine the expected intensity level to be sensed in order to select the appropriate instrument range setting to be used during monitoring. It is necessary to determine the time when the vibration source is active. Specific activities of the vibration source, such as driving of piles, as opposed to extraction, vibratory compaction, or pavement-breaking activities, should be indexed in time for proper correlation with the arrivals on the vibration records. Because the determination of frequency is important, instruments that provide a time-history or waveform of each velocity component for a vibration event are preferred.
A field calibration procedure should be conducted before the start of monitoring and recording. The incoming ground vibrations should be measured on the ground at foundation level, as close to the structure as possible, to be consistent with studies providing safe vibration limits (Siskind and Stagg, 1985). The transducer is positioned with the longitudinal axis (indicated by an arrow) toward the vibration source or parallel to the structure. Transducers must be adequately coupled with the ground or the structural component being monitored (see Section X 1.5, Appendix X 1). Instrument manufacturers provide appropriate instructions and recommendations for special installations. Some published threshold criteria are based on specific monitoring procedures. Consistent procedures in the placement and location of transducers during monitoring are recommended for comparison of results.
Records of the incoming vibrations are typically displayed in a waveform plot or strip chart plot. The peak particle velocities in longitudinal, transverse, and vertical planes are shown along with the respective dominant or principal frequencies. The highest recorded particle velocity among the three planes is indexed to its time of occurrence within the recorded interval. This velocity is reported as the peak particle velocity for a particular event.
The recorded peak particle velocity is compared with criteria appropriate for the subject of concern. Many currently used digital instruments produce a record that displays the particle velocities and associated zero-crossing frequencies, or arrivals plotted against a base of the U.S. Bureau of Mines (USBM) RI 8507 curve, which is a commonly accepted criterion for threshold cracking concerns in the United States (see Figure X2. 1). Other criteria may be applicable in special circumstances (see Appendix X2).
In the event of a complaint, a site visit should be made as soon as possible to assess the situation and to compile necessary documentation. A report document should include all relevant data, such as the basis for the investigation, time and date of the survey, persons involved, and a description of the property. It should also include a description of the instrumentation; a description and log of the monitoring procedure; the monitoring results; and the conclusions reached based on comparison with applicable criteria, standards, or expert recommendation.AASHTO R8-96 pdf download.