AASHTO T 385-19 pdf free download

AASHTO T 385-19 pdf free download.Deep Foundation Elements under Bidirectional Static Axial Compressive Load .
5.2.2. An apparatus capable of applying a total load greater than or equal to the desired test load shall he considered acceptable, noting that in a bidirectional test, the total load applied is the sum of the load applied above and below the loading assembly plus the mass of the pile above the jack. However, it is preferred to have load capabilities well beyond the test load to allow full mobilization of the pile and to provide data for possible foundation redesign. The jack shall be able to maintain a constant load for appropriate durations of Lime (according to specified loading schedules) to within 2 percent. The typical method of measuring this force includes the use of calibrated jacks.
5.2.3. The hydraulic jacks shall be confined in a symmetrical arrangement (centered if a single jack) between the upper and lower reinforcing cages or carrying frames to facilitate construction of the pile and to locate the loading device at the designed level. Steel bearing plates having cutouts of sufficient size shall be provided to accommodate the nominal diameter of the tremie pipe and to allow for adequate flow of concrete around the apparatus. These bearing plates shall be symmetrical and centered about the longitudinal axis of the reinforcing cage or carrying frame. Appropriate spacers shall be used to centrally locate the reinforcing cage or carrying frame pile within the borehole.
5.2.4. The loading assembly shall be accurately placed at a distance above the pile toe level as specified for the test and shall be a minimum distance of one-half pile diameter above the pile bottom, unless otherwise directed by the engineer. This assembly shall be welded or otherwise securely attached to the reinforcing cage or carrying frame. The spiral reinforcement and vertical steel bars shall be terminated immediately above and below the expected fracture plane.
5.2.5. All pumps, hydraulic jacks, hoses, and fittings shall be designed and rated to safely confine the internal operating pressures.
5.2.6. Vent tubes shall be installed at the fracture plane to minimize any vacuum resulting from expansion of the load jack, unless otherwise directed by the engineer. The vent tubes shall be secured along the length of the pile. Vent tubes shall be clean and filled with clear water for testing.
5.3. Data Acquisition In.strun, en (anon:
5.3.1. General:
To determine the behavior characteristics of the foundation element, the test instrumentation must be capable of accurately measuring values of applied force (load), jack expansion, top-of-pile displacement. linear pile compression. and concrete strain as required by the engineer. Using these data, the engineer can determine reasonable values for unit side shear, unit end bearing, and settlement. l’hese measurements must he recorded at specified time intervals not greater than 1 mm unless otherwise directed by the engineer.
The measured displacements provide for the following:
• Top-of-pile movement (measured by displacement transducers attached to the reference beam set over the pile or by remote optical electronic levels):
• Pile compression (measured by encased compression telltales LEC1’sl and traditional telltale rods set from the top of hydraulic jack and referenced to top of pile or reference frame);
• Upward top ofjack movement (calculated as measured pile compression above the jack plus measured top-of-pile movement):AASHTO T 385-19 pdf download.