Linear soil–structure interaction of coupled wall–frame structures on pile foundations

The effects of soil–structure interaction on the response of coupled wall–frame structures on pile foundations subjected to moderate earthquakes are investigated in this paper. A linear finite element procedure for a complete dynamic interaction analysis is developed in the frequency domain accounting for soil–pile interaction and radiation damping. The procedure allows accounting for the actual deformability of the soil–foundation system and modification of the input motion due to the embedded foundation. The free-field motion is obtained by means of a local response analysis, which accounts for site amplification. The procedure is adopted to study the effects of compliant pile foundations on the seismic damageability of a coupled wall–frame system. Three different soil profiles are considered and real accelerograms are used as input motions. The calculated results, expressed in terms of the response parameters most significant for the description of damage (such as displacements, inter-storey drifts, accelerations and stress resultants), are compared with those obtained from a conventional fixed-base model. Applications demonstrate that performing complete soil–structure interaction analyses may be crucial for the correct evaluation of the behaviour of such systems.

► SSI analysis includes pile–soil–pile interaction and site effects.
► Analysis is performed with a direct approach in the frequency domain.
► Superstructure is properly modelled and SSI effects are evaluated in each element.
► Wall rocking strongly modifies the stress resultant distributions in wall and frame.
► Inter-storey drifts significantly increase as a consequence of foundation rocking.