Structural　optimization　of　arches　under　multi-load　cases　is　faced.　For　this　aim,　truss-type　arches　are　to　be　considered　because,　under　different　load　cases,　bending　effects　unavoidably　occur　in　single-rib　arches　shaped　under　one　load　case　only.　An　effective　procedure　for　simultaneous　topology,　shape　and　size　optimization　of　truss-arches　under　multi-load　cases　is　proposed.　For　this　aim,　shape,　size　and　topology　variables　are　assembled　in　a　unique　set　of　variables　that　are　simultaneously　optimised　by　the　optimization　algorithm.　For　given　Pratt-type　brace　pattern,　different　topologies　have　been　considered　by　varying　the　node　number,　whereas　Cubic　Rational　Bézier　curves　have　been　used　to　shape　the　arch　chords.　Optimum　diameter　and　thickness　of　the　circular　hollow　section　members　was　also　obtained.　Optimization　was　performed　in　MATLAB　environment,　by　applying　a　modified　Differential　Evolution　(DE)　algorithm　implemented　with　a　Constraint　Domination　Selection　(CDS)　criterion.　For　each　design　variable　vector,　a　FEM　analysis　of　the　resulting　model　has　been　carried　out　by　SAP2000　to　evaluate　the　objective　function　value　(volume)　feasibility　of　each　design　variable　vector　in　terms　of　structural　performance.　Optimal　solutions　have　been　found　and　compared,　providing　useful　suggestions　to　consider　as　guidelines　in　truss-arche　design.　©　20th　Congress　of　IABSE,　New　York　City　2019:　The　Evolving　Metropolis　-　Report.　All　rights　reserved.