Displacement-based design of soil–foundation–structure systems

Abstract

In this paper a displacement-based design procedure is presented to rationally account for the effects of soil–foundation–structure interaction (SFSI) in the seismic design of shallow foundations. The non-linear deformations at the soil–foundation interface, such as foundation uplift, soil yield and soil–foundation shear deformation can dramatically alter the dynamic response of a building. The lack of consideration of the modifying factors of SFSI and an absence of procedures for controlling foundation and soil behaviour under seismic loads have resulted in inadequate designs for buildings sited on soft soil. A soil–foundation macro-element model was used to calibrate expressions to quantify the non-linear foundation rotational stiffness as well as the effects of foundation energy dissipation and soil–foundation shear deformation on the response of the soil–structure system. A series of concrete wall buildings were designed with the proposed design procedure and numerically assessed to validate the suitability of the design procedure. The simple hand calculation procedure presented here quantifies the modifying factors of SFSI in an intuitive and direct manner to allow engineers to design building–foundation systems with a clear understanding of their expected performance.

An integrated performance‐based design framework for building‐foundation systems

“…The estimation of the peak deformations is a key step in the performance‐based design procedure and can be achieved using the DBD procedure given in Millen et al 10 . The DBD procedure estimates the displacement demand on the building‐foundation–soil system by converting the system to an equivalent single degree‐of‐freedom (SDOF) with an effective system displacement (), effective mass (), and effective height () using Equations ().…”

“…The effective shear stiffness and the DRF from soil‐foundation shear deformation can be taken as half the elastic stiffness and 0.76, respectively, provided the soil‐foundation shear deformation contributes less than 20% to the total displacement 10 …”

“…Finally an estimation of the foundation rotation is needed. In the method by Millen, 10 the foundation rotation and effective rotational stiffness are iterated using Equation () to satisfy the equilibrium of the moments applied at the foundation (, Equation ()). …”

“…One of the causes for unintentional foundation deformations is the disconnect between the design of the superstructure and that of the foundation, whereby the superstructure is designed first, and the foundation second. The use of an integrated design process where the superstructure and foundation are designed concurrently removes the issues caused by a decoupled design approach 10 . In recent times there has been a growing appreciation that foundation uplift and soil yielding can provide suitable mechanisms for energy dissipation 9 .…”

Determining the interfaces parameters for geotechnical modelling

“…This topic has several approaches to the study that have emerged in the present. Among them are the development of models for the interaction of soil and structures [8][9][10][11], the conduct of test studies of the interaction of dissimilar materials [12][13][14][15][16], and the performance of numerical simulations to verify the found effects that occur in the interaction of structures with the soil [17][18]. In this paper, the authors used the last two directions as the main ones for obtaining the required interface parameters and using them in geotechnical numerical calculations.…”