Shifferaw, Taye (PhD)Betelhem, Asmare2020-11-182023-11-112020-11-182023-11-112017-10http://etd.aau.edu.et/handle/12345678/23365Lifeline systems are intricately linked with the economic well-being, security, and social fabric of the communities they serve. When earthquakes or other hazards strike lifeline systems, they disrupt the flow of resources and provision of services that sustain communities. Many Lifeline systems are long-span structure. These structures are extended horizontally to allow people, goods, electric power, gas and other item to move freely between locations. When seismic ground motion strikes, these structures may be affected and, consequently, the economy aspect of a country can be disrupted there by leaving people at risk. The purpose of this thesis has been to investigate the influence of soil-structure interaction on a dynamic property of above-ground pipeline (as an example of long-span structures and lifeline facilities) for five different support conditions. Three-dimensional (3D) linear finite element analysis of above-ground pipeline for a different base conditions have been made with the help of general purpose software ABAQUS. For this study, a 12m nominal length of a pipeline with API 5L X80 material grade has been used and models have be studied for Kobe 1995 earthquake ground motion. Dashpot and the spring coefficient for a typical foundation have been establish for use in substructure approach for the analysis. From analysis, it has been noted that, the displacement of pipelines on the soft soil to be larger than the displacement of pipeline laid on other type of soil support. It has also been observed that, when the base condition become more flexible, the values of all response increased. In a view of these observation, therefore, considering SSI effects in seismic design of above-ground structures resting on flexible support conditions like soft soil deposit is essential to minimize the potential damage of earthquake. From this thesis, it is recommended that, incorporating SSI for lifeline systems (similar to above-ground pipeline structure) is important in order to assure the safety of the structure.en-USSoil-Structure InteractionSeismic ResponseGround PipelinesThesis