Multi-variable relations for simplified evaluation of soil-pile kinematic effects

Within the context of a performance-based design, the maximum kinematic bending moment can be considered a good descriptor of pile performance under seismic loads as, in the current design, piles are assumed to remain in the elastic domain. Closed-form expressions for evaluating the kinematic bending moment at the interface of two soil layers have been elucidated and a new procedure, fully analytical, has been proposed based on the former work of Cairo et al. [2009b]. This procedure allows computing pile kinematic bending moment by means of formulas and design charts based on a limited number of subsoil and input motion simple parameters. The subsoil is identified by means of geometrical and mechanical properties, whereas the input motion is identified by only two parameters: the peak acceleration on rock, arock, together with the mean period, Tm, or the response spectrum intensity, SI. The peak acceleration on rock is usually provided by the seismic zonation incorporated in national codes; the latter two parameters may be obtained on the basis of well-consolidated literature indications.