Geotechnical site conditions that can be very different due to changes in t
hickness and properties of soil layers, depth of bedrock and water table ar
e among the main factors controlling earthquake characteristics on the grou
nd surface. Soil layers subjected to cyclic stresses may lead to degradatio
n of stress-strain and shear strength properties. The laboratory tests were
conducted to evaluate the changes in the stress-strain and shear strength
characteristics in terms of threshold cyclic shear stresses and cyclic yiel
d stress. The effects of local site conditions are assessed based on geotec
hnical site conditions and earthquake source characteristics. (C) 2001 Publ
ished by Elsevier Science Ltd.