Javier Avilés

Effects of foundation embedment during building–soil interaction

SUMMARY A numerical solution for evaluating the e⁄ects of foundation embedment on the e⁄ective period and damping and the response of soil—structure systems is presented. A simple system similar to that used in practice to account for inertial interaction e⁄ects is investigated, with the inclusion of kinematic interaction e⁄ects for the important special case of vertically incident shear waves. The e⁄ective period and damping are obtained by establishing an equivalence between the interacting system excited by the foundation input motion and a replacement oscillator excited by the free-field ground motion. In this way, the use of standard free-field response spectra applicable to the e⁄ective period and damping of the system is permitted. Also, an approximate solution for total soil—structure interaction is presented, which indicates that the system period is insensitive to kinematic interaction and the system damping may be expressed as that for inertial interaction but modified by a factor due to kinematic interaction. Results involving both kinematic and inertial e⁄ects are compared with those obtained for no soil—structure interaction and inertial interaction only. The more important parameters involved are identified and their influences are examined over practical ranges of interest. ( 1998 John Wiley & Sons, Ltd.

Effective periods and dampings of building-foundation systems including seismic wave effects

Effective periods and dampings of a refined soil-structure system similar to that used in practice to account for the inertial interaction effects are determined, including the kinematic interaction effects for the important special case of vertically incident shear waves. A three-dimensional axisymmetrical model consisting of a single structure with embedded foundation in a soil layer over elastic bedrock is examined. The impedance functions and the input motions for the foundation are computed respectively by an efficient numerical technique and the well-known Iguchi averaging method. Effective periods and dampings are determined for a large number of system configurations. Results are presented by means of dimensionless charts that should be used by designers in code-analyses of soil-structure interaction. Diagrams should also be of use in preliminary analyses to assess the influences of the principal parameters involved. Moreover, accurate approximate formulas for the effective period and damping are proposed, the use of which is very simple.

Updated Seismic Design Guidelines for Model Building Code of Mexico

The Manual of Civil Structures (MOC), a model design code in Mexico, has been in the process of being updated, and the new version of this code was published in 2008. A major update from the 1993 version was performed in the chapter for the seismic design of building structures. This paper summarizes the most relevant changes of this building code and their relation to research efforts conducted within Mexico and worldwide to improve the seismic design of building structures. One goal is to make the guidelines as transparent as possible to users, so that the design process will be clearer to structural engineers.

Response of L-shaped rigid foundations embedded in a uniform half-space to traveling seismic waves

Abstract A simplified indirect boundary element method is applied to compute the impedance functions for L-shaped rigid foundations embedded in a homogeneous viscoelastic half-space. In this method, the waves generated by the 3D vibrating foundation are constructed from radiating sources located on the actual boundary of the foundation. The impedance functions together with the free-field displacements and tractions generated along the soil–foundation interface are used to calculate the foundation input motion for incident P, S and Rayleigh waves. This is accomplished by application of Iguchis averaging method which, in turn, is verified by comparison with results obtained rigorously using the relation between the solutions of the basic radiation (impedance functions) and scattering (input motions) problems. Numerical results are presented for both surface-supported and embedded foundations. It is shown how the seismic response of L-shaped foundations with symmetrical wings differs from that of enveloping square foundations. The effects of inclination and azimuth of the earthquake excitation are examined as well. These results should be of use in analyses of soil–structure interaction to account for the traveling wave effects usually overlooked in practice.