In　the　last　few　years,　the　integral　abutment　bridge　(IAB)　concept　has　become　quite　common.　It　is,　incidentally,　not　a　newly　developed　concept,　its　formulation　dating　back　at　least　to　the　1930s,　in　order　to　deal　with　long-term　structural　problems　frequently　occurring　with　conventional　bridge　design.　At　present,　the　IAB　concept　is　generating　considerable　interest　among　bridge　engineers　because　of　the　enormous　benefits　due　to　elimination　of　expansive　joints　and　reduced　installation　and　maintenance　costs.　The　superstructure　of　integral　abutment　bridges　is　made　continuous　through　a　composite　cast-in-place　concrete　deck　slab　over　prestressed　concrete　or　steel　girders　and　continuity　diaphragms,　and　the　system　constituted　by　the　sub-　and　the　super-structure　acts　as　a　single　structural　unit.　A　usual　and　important　problem　in　the　design　of　IABs　is　how　to　deal　with　the　soil-structure　interaction　behind　the　abutments　or　next　to　the　foundation　piles:　this　can　be　considered　as　a　fundamental　aspect　for　the　thorough　understanding　of　this　type　of　structures,　which　requires　iterative　and　nonlinear　analysis.　In　this　paper,　a　2D　simplified　finite-element　model　of　a　real　400　meters　long　IAB,　built　in　the　Province　of　Verona-Italy,　will　be　implemented　and　used　to　perform　non　linear　analysis　on　the　bridge.　Then,　based　on　the　results　obtained　from　a　parametric　study　on　the　IAB,　the　analysis　of　effects　of　soil-pile　interaction　and　the　abutment　size　will　be　carried　out　to　find　out　the　relative　key　parameters　in　IABs　design.