抄録
The surface and downhole accelerations records of "Central de Abasto Oficinas (CAO)" array at Mexico City, have been analyzed to determine the soil stiffness and damping ratio as a function of shear strain amplitude. The 3/31/93, 24/10/93, 23/05/94, 10/12/94 and 09/10/95 seismic events have been used for this purpose. The shear stress-strain histories have been evaluated directly from the field downhole acceleration records, employing a technique of system identification, and have been used to obtain the variation of shear modulus and damping ratio with shear strain amplitude. A shear-beam model, calibrated by the identified properties, is found to represent the site dynamic response characteristics. The results have been compared with values obtained by previous authors using field and laboratory tests.
