The Earthquake Engineering Online Archive

Structure-foundation interactions under dynamic loads

Liu, Wen David; Penzien, Joseph

UCB/EERC-84/18, Earthquake Engineering Research Center, University of California, Berkeley, 1984-11, 222 pages (535/L58/1984S)

Interactions as characterized by the dynamic foundation stiffnesses are studied for embedded foundations and single piles based on the general substructure method. The hybrid modeling technique has been applied to rigid or flexible cylindrical foundations embedded in a viscoelastic halfspace. The semi-infinite far-field beyond a hemispherical surface is approximately represented by uniformly distributed dynamic impedances developed previously. Foundations of different embedment ratios are considered. For single piles, a semi-analytical continuum method is adopted which uses solutions for a dynamic point load buried in a viscoelastic halfspace. The soil modulus is defined as the inverse of an average displacement caused by loads uniformly distributed over the cylindrical pile surface. The foundation radiation damping coefficients (frequency-independent) have been included as discrete viscous dashpots in a time-domain nonlinear analysis computer program for bridge structures. The multiple-support-excitation capability has been implemented. To illustrate the foundation effects, a pilot case study has been carried out for a six-span segment of a typical highway bridge.

Available online: http://nisee.berkeley.edu/documents/EERC/EERC-84-18.pdf (36 MB)