Discussion of “seismic uplift capacity of horizontal strip anchors using a modified pseudodynamic approach” by anindya pain, deepankar choudhury, and s. K. Bhattacharyya

Abstract

The discussers appreciate the authors for presenting an interesting paper on the determination of seismic uplift capacity of shallow horizontal strip anchors embedded in cohesionless soil using a modified pseudodynamic approach. The authors have extended the applicability of the new pseudodynamic approach proposed by Bellezza (2014). Steedman and Zeng (1990) first proposed pseudodynamic approach by considering the effect of the finite shear-wave velocity, horizontal seismic acceleration, and amplification of vibrations. Later, Choudhury and Nimbalkar (2005) modified the pseudodynamic approach proposed by Steedman and Zeng (1990), wherein they incorporated the effect of vertical acceleration due to vertically propagating primary waves. The effects of time, the phase difference, and the effect of amplification in both the shear and primary waves propagating through the soil were taken into account in this modified pseudodynamic approach. Numerous problems have been solved using this modified pseudodynamic approach proposed by Choudhury and Nimbalkar (2005). Again, there are two main disadvantages associated with the modified pseudodynamic approach: (1) zero-stress boundary conditions at the ground surface are not satisfied, and (2) amplification of the acceleration value is assumed to vary linearly toward the ground surface. By satisfying zero-stress boundary conditions at the ground surface, both vertical and horizontal accelerations were derived (Choudhury and Katdare 2013) considering earthquake waves, such as shear, primary, and Rayleigh waves. However, the variation of phase, but not the magnitude of acceleration, was taken into account. Recently, a new pseudodynamic approach was suggested by Bellezza (2014) to obtain the active thrust on a rigid retaining wall, where the aforementioned shortcomings associated with the modified pseudodynamic approach can be eliminated. In this new pseudodynamic approach proposed by Bellezza (2014), only the equation of the horizontal acceleration is derived in a closed-form fashion considering the soil as a Kelvin–Voigt material. The authors used this new pseudodynamic approach developed by Bellezza (2014) to compute the seismic uplift capacity of horizontal strip anchors, which is an important contribution to the application of this new pseudodynamic approach aiming to overcome the disadvantages stated as earlier.