The bearing system of a 3 story exhibition pavilion in Virovitica is designed and calculated in this thesis. The floor plan is circular with an axial diameter of 34 meters formed in a way that there is a minimum number of columns in the interior space. The load bearing system of the structure is the core with staircase for vertical communication placed inside of it. The core consists of seven fixed frames that are stabilized by concentric bracings outside of the plane. The frame system is composed of composite columns, and, on the ground and first floor of HEB steel beams, while on the 2nd floor steel trusses 2 meters high are used. Eccentricity between the first and ground floor is 10.5 meters, and both floors are suspended from the core of the structure usin a lattice girders supported with two continuous columns. The interstorey structure is a composite floor system Cofraplus 220 whose ribs are placed perpendicular to the direction of the main composite beams. Steel quality S275 is used for steel load-bearing elements, while concrete strength is C50/60 in the composite columns, and C25/30 in the composite slab. The welded connections of the elements are previously made in the workshop, while the bolted connections are used for mounting on the construction site. The technical description, structural drawings, structural analysis and workshop drawings of characteristic connections are attached as a part of the thesis.