The effect of monolith interaction on the overall dynamic response of
concrete gravity dams is investigated For this purpose, a simplified a
pproach is proposed that is capable of including the effect of the lon
gitudinal direction on the response of the critical monolith. The mono
liths are represented by beam elements connected by shear links. The e
ffect of hydrodynamic interaction is considered as added mass to the d
am structure. The results of this innovative approach are compared to
those of a typical three-dimensional analysis and good accuracy is obt
ained. It is noted that the fundamental frequency of dams with keyed c
ontraction joints increases when monolith interaction is included. The
structure tends to be Stiffer and, depending on the input ground moti
on, may have lower response values than those predicted using typical
two-dimensional analysis. The procedure developed in this study has it
s limitations but can include the longitudinal effects along the axis
of the dam in the response analysis efficiently and fairly accurately.