Effects of Cyclic Frequency and Pre-Loading on Behaviour of Plate Anchors

This paper reports the response of embedded circular plate anchors to varying frequencies of cyclic loading. It also highlights the effect of pre-loading on anchor movement and post-cyclic monotonic pullout behavior using model circular plate anchor, buried at embedment ratio of six in soft saturated clay. The frequencies of loading cycle are found to have considerable effect on anchor movement. For a given duration of loading, high frequency cycle causes more anchor movement than that caused by low frequency cycles. Pre-loading causes a reduction of anchor movement in subsequent loading stages. Anchors subjected to cyclic loading and then monotonic pullout, show stiffer load-displacement behaviour at an initial stage compared to anchors not subjected to any cyclic loading. Pre-loading causes a reduction of anchor movement in subsequent loading cycles. When anchors are recycled at a load ratio level less than the pre-cycling load, the anchor movement in the recycling phase is very much reduced, but if the recycling is done at a higher load ratio level, the effect is not that pronounced, and the anchors behave as if they were not subjected to any cycling load in the past. The relative post-cyclic stiffness of anchors for the present test conditions varies from 1.169 to 1.327.