Behavior of Sand/Concrete Interfaces under Dynamic Loads.
Final rept. Apr 85-Jul 86,
WASHINGTON STATE UNIV PULLMAN
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The objective of this research effort was to conduct an experimental program to determine the dynamic shear response of dry sandconcrete interfaces. A series of dynamic direct shear interface tests was performed using Yuma and McCormick Ranch sands in contact with concrete. Each concrete specimen was cast against a plywood form. These experiments were conducted using various values of normal stress, shearing velocity, and sand density. Results obtained from the experiments indicate that peak strength of the interface was not rate dependent, while residual strength decreased with increasing shearing velocity. Interface strength was found to be 100 to 108 percent of the strength of the surrounding sand. Theoretically, the interface strength is limited by the strength of the sand. This discrepancy is attributed to experimental error. It is recommended that the strength of a dry sandrough concrete interface be modelled using a Mohr envelope with a friction angle of 90 to 100 percent of the friction angle of the sand. This Mohr envelope would also be modified to model the curved envelope of typical sands when large ranges of normal stress are anticipated. It is also recommended that postfailure response be modelled by a perfectly plastic model when high magnitude normal stresses were applied, a near plastic behavior was observed beyond normal stresses of 2.5 MPa.
- Structural Engineering and Building Technology