Response of anchors to variations in displacement-based loading

The results of an experimental investigation on the effect of variations in displacement-based loading on the pullout capacity of anchors are presented. A single-pitch, screw helical anchor was used in the testing. The tests were conducted in dry, well-graded, dense, medium, and loose sands with relative densities of 79, 47, and 19%, respectively. Anchors were installed to, and tested at, shallow and deep depths. Measurements of ultimate pullout load and displacement at failure were made. The values of time-to-failure and mean loading rate were calculated and presented. The results of this study show that variations of displacement-based loading had some effect on the pullout capacity of shallow anchors but had only a slight effect on deep anchors. For a given depth of installation and a given sand state, the ultimate pullout load of an anchor decreases with increasing loading rate. This effect was more pronounced in anchors installed to shallow depths.