DYNAMIC SOIL-STRUCTURE INTERACTION FOR RC LIFELINES.

The behavior of buried cylinders merits attention because of the impact of lifeline survivability under earthquake effects, and failures may adversely affect many communities that employ such systems. It has been ascertained that the soil has significant effect on the response of such structures, and vice versa. This interaction effect is mainly arised from the relative flexibility between the soil and structure. The main purpose of this work is to obtain an overall understanding of the behavior of rectangular reinforced concrete (RC) cylinders under earthquake effects through the use of numerical methods. It was found that for the simple elastic analysis, the peak stresses of the structure occurred at the lower corners, and increased substantially as the embedment depth was increased. The peak stresses in the nonlinear domain for the no-embedment case were generally higher than those in the linear domain. As far as the structural damage is concerened, based on the velocity criteria, it seems tolerable at this stage since no major cracks were observed. The interface was expected to exhibit relative soil-structure motions such as sliding and separation, as indicated by stress levels obtained in the present study. As the embedment is increased, additional reinforcement should be properly provided in the corner joints of the structure, especially at the lower corners, to prevent the noted failures.