Seismic uplift resistance of circular plate anchors in sand

In the present study, theoretical solutions have been developed for computing the vertical seismic uplift resistance of a shallow buried horizontal circular plate anchor in sand with the incorporation of shear transfer at the interface of the anchor plate and overlying sand during an earthquake. The analysis was performed by employing the kinematic theorem of limit analysis based on a pseudo-static approach, with the assumption of a simple rigid wedge collapse mechanism in the form of an inverted frustum with cross-section changing from circular at the anchor level to an elliptical shape at any level just above the anchor. The effect of seismic body forces on the uplift capacity of the circular anchor is evaluated in terms of dimensionless seismic factors S_q and S_γ due to the components of surcharge pressure and soil unit weight, respectively. An increase in the magnitude of seismic acceleration leads to a continuous reduction in uplift resistance; a significant decrease in the uplift resistance was found to occur for the case with the consideration of shear at the interface between the anchor top surface and the soil as compared to that without any shear.