This thesis presents the investigation of the performance of the concept of piled raftrnfoundation compared to the conventional pile and raft foundation for Addis Ababa soils.rnThe investigation has been carried out using soil profiles in Addis Ababa where highrisernbuildings are going to be constructed and have been already constructed. Tornsupport the results of the investigation, soil profile from Wabe Shebele River bridge siternhas been also considered.rnIn this work, first, different design philosophies and method of analysis have beenrndiscussed. From already available methods of analysis, the hybrid method of analysisrnhas been chosen for its computational efficiency. The program is validated by anaysingrnexamples available in literature and has already been analyzed using 3D finite elementrncode (FLAC 3D).rnThen, two case studies have been made to explore the performance of the piled raft forrnAddis Ababa soils. The first case is the Awash bank head quarter building, which isrngoing to be constructed near national theater. The second case considered is the soilrnprofile on which the former marine transport authority building is constructed. For bothrncases, comparison has been made among raft, pile, and piled raft foundation based onrnsettlement and bending moment.rnAnother case study, conducted to supplement the out come of the foregoing two cases, isrnthe abutment foundation of Wabe Shebele River Bridge. This case specificallyrnconducted aiming at reducing the total settlement of the foundation that is above thernpermissible limit for masonry abutment. For the this case, the results have shown thatrnvrntwo fifth of the number of piles required for conventional piles can be reduced usingrnpiled raft design concept. When raft alone is used, the settlement exceeds thernpermissible value.rnGenerally, it has been observed that piled raft concept is very advantageous inrnminimizing the total and differential settlements as compared to the conventional raftrnfoundation. It also reduces number of piles required as compared to the conventionalrnpile foundation. For the cases investigated in this work, the reduction in number ofrnpiles ranges from 25% to 45% of that required for conventional pile foundation, thoughrnthe variation in raft bending moment and other issues are no considered in detail.