Unified analysis of kinematic and inertial earthquake pile responses via the single-input response spectrum method

Abstract

In the seismic response of a structure-pile-soil system, a kinematic response due to the forced displacement of the surface ground is important, especially in a soft ground, together with the inertial response due to the inertial forces from superstructures. In this paper it is shown that a response spectrum method in terms of complex modal quantities can be used in the evaluation of the maximum kinematic and inertial seismic responses of the structure-pilesoil system to the ground motion defined at the engineering bedrock surface as an acceleration response spectrum. The notable point is that the kinematic response, the inertial response and the total response can be evaluated by the same analysis model and method by changing the model parameters. Then it is discussed which of the simple sum or the SRSS of the kinematic and inertial responses is appropriate even in resonant cases for the evaluation of the maximum pile-head bending moment. It is concluded through many examples that the validity of the simple sum or the SRSS depends on the relation between the fundamental natural period of the surface ground and that of the superstructure while an averaged evaluation is valid in resonant cases.

A review on soil–structure interaction analysis of laterally loaded piles

“…A set of numerical formulations for advanced analysis of soil-structure interaction is developed by many researchers [46,47,50,99,100]. A new frequency domain method for evaluating the earthquake input energy to a structure-pile system or a superstructure alone subjected to horizontal ground motion was developed by Takewaki et al [100].…”

“…The method was further modified as a unified response spectrum method incorporating the kinematic and inertial effects as shown in Fig. 7 [47,50]. The equilibrium equation is derived for the structure-pile-soil system and is represented in Eq.…”

“…8 Building pile system supported by the free-field ground through winkler type soil model [50] Fig. 9 Sketch of bending moment distribution in fixed head pile group [105] the difference in maximum bending moment and pile top deflection in comparison to the other's methods.…”

Prediction of worst combination of variable soil properties in seismic pile response

“…In this paper, a soil-pile-structure interaction system subjected to an engineering bedrock input ground motion is considered [6][7][8][9][10][11] and the soil properties (stiffness and damping ratio) are treated as interval parameters (see [12][13][14][15]). Then the upper and lower bounds of its earthquake response are evaluated.…”

“…A response spectrum method due to Kojima et al [10,11] is used in this paper for evaluating the maximum seismic pile response. In order to investigate the accuracy of the method used in this paper, the upper bound derived by GA (Genetic Algorithm) is compared with the result by the present method.…”