International Journal of Research in Engineering and Applied Sciences(IJREAS) Available online at http://euroasiapub.org/journals.php Vol. 7 Issue 5, May-2017, pp. 120~133 ISSN (O): 2249-3905, ISSN(P): 2349-6525 | Impact Factor: 7.196 | Thomson Reuters Researcher ID: L-5236-2015 International Journal of Research in Engineering & Applied Sciences Email:- editorijrim@gmail.com, http://www.euroasiapub.org An open access scholarly, online, peer-reviewed, interdisciplinary, monthly, and fully refereed journals 120 Performance of Raft with Non uniform piles under different vertical load conditions Prashant Garg ͳ , Assistant Professor, & Research scholar, )KGPTU, Guru Nanak Dev Engineering College, Ludhiana )ndia Jagadanand Jha ʹ , Professor, Guru Nanak Dev Engineering College, Ludhiana )ndia (arvinder Singh ͵ , Professor, Guru Nanak Dev Engineering College, Ludhiana )ndia ABSTRACT The design of pile raft foundation system ȋPRFSȌ had already been proved economical solution to heavy structure and it is being used in many parts of world successfully including in tallest tower, Burj Kalifa. Still a lot of research is being carried out to get a simpler and handy method to design pile raft foundation but most of work is being carried out, using uniform piles. )n the present study, use of piles of different lengths and diameters at critical location was investigated to bring a more economical solution so that every pile may be fully utilized up to its full capacity. Plaxis ͵D, a FEM based specialized software was used to analyze this, a complex problem of soil structure interaction. The study was carried out for two types of load on footing as centric load ȋaxial ColumnȌ and eccentric load ȋuni axial or biaxial columnȌ. Short and thinner piles were replaced with longer and thicker piles at some critical location as center of footings, at all corners of footing for both cases of loading condition and at edge of footing for eccentric footing. )t was observed that for centric loading, it is economical to have longer piles at corners and thicker pile at center and in case of eccentric load, thicker and longer piles must be provided at compressed edge of footing to be more economical. Keywords: Pile raft, Non uniform piles, centric load, Eccentric Load, FEM )NTRODUCT)ON The recent research of Pile raft foundation proved to be a economical and reliable foundation system without compromising the safety of superstructure as advocated by many researchers [ͳ- Ͷ]. A variety of design methods from a simplified approach to very complex method involving various soil structure interaction. Most of the studies are based on Finite Element Methods [ͷ-ͳʹ] whereas few studies have been reported with small scale model in laboratory [ͳ͵-ͳͺ]. Most of the research whether it is based on simplified approach or based on Finite Element Method, uniform