Solving complex concrete and steel joints in a Croatian sports hall
\[ \textsf{\textit{\footnotesize{Global 3D model of the structure}}}\]
About the Project
The project involved the structural design of a new sports hall with a dual-material frame: reinforced concrete for vertical and interfloor components, and steel for the roof structure. The building spans a total footprint of 61.49 by 37.38 meters, with the central hall defined by a 36.48-meter-wide truss-supported steel roof. The roof itself combines a single-pitched and double-pitched layout, while the reinforced concrete component includes gallery slabs, stairwell corridors, and inclined spectator stand platforms. The structural design was entrusted to Reverto Projekt, led by Robert Tudor and supported by Antonija Rončević, with Alen Leljak serving as head designer.
Engineering Challenges
The primary challenge was the interaction between the reinforced concrete and steel structural systems. The steel roof trusses were fixed to reinforced concrete columns and gable beams to create a monolithic diaphragm action. These connections not only had to transfer high moment and shear forces but also contribute to the global horizontal stability of the hall through the realization of a rigid roof disk.
\[ \textsf{\textit{\footnotesize{Steel-to-concrete structural detail}}}\]
This necessitated joint detailing capable of withstanding a range of loads: self-weight, permanent equipment, service use, snow, wind, temperature effects, and seismic activity. The analysis needed to account not just for stress and strain but also for the rotational stiffness of joints. Inadequate stiffness could compromise the integrity of the global model, leading to significant performance risks.
\[ \textsf{\textit{\footnotesize{Stiffness diagram My-ϕy}}}\]
Further complexity was introduced by the layout geometry — with the first roof grid featuring a single pitch at 9° and the remaining spans shaped as double-pitched roofs at 6°. These variations in slope altered load paths and affected how forces were introduced into joints. Additionally, interfloor concrete slabs, including the stepped and inclined spectator seating, added asymmetry to the vertical loading pattern, increasing the importance of accurate modeling and analysis.
Solutions and Results
To manage this complexity, the engineering team turned to a highly integrated workflow centered on IDEA StatiCa’s Connection application. Connection models were developed and verified in IDEA StatiCa, with data imported directly from SCIA Engineer’s global analysis. This seamless integration eliminated redundant modeling and helped streamline the design cycle.
\[ \textsf{\textit{\footnotesize{3D model of the structure in SCIA Engineer}}}\]
Allplan was used to develop reinforced concrete detailing and formwork plans, while Tekla Structures supported workshop documentation. The Tekla–IDEA StatiCa plugin allowed detailed verification of connection designs directly from the 3D model, ensuring accuracy and reducing rework. Specific connections, including anchoring the roof truss to concrete gables, joining secondary roof beams, and detailing truss diagonals, were modeled and optimized within IDEA StatiCa, benefiting from its clear visualization and compliance checks.
\[ \textsf{\textit{\footnotesize{Anchoring of the roof truss structure to the gable RC frames}}}\]
Stiffness analyses, visualized through moment-rotation (My-ϕy) diagrams, confirmed joint rigidity and structural performance. Multiple connection types, including anchoring of roof trusses to gable RC frames, secondary steel-to-RC beam fixings, diagonal truss connections, and base joint assemblies, were calculated with full Eurocode compliance.
About Reverto projekt d.o.o.
Reverto projekt d.o.o. is a design office founded in 2008 with headquarters in Ivanić-Grad, owned and led by an
experienced civil engineer (primarily a structural engineer), Robert Tudor, mag.ing.aedif. The company primarily focuses on structural design projects in building construction, although it occasionally solves other challenges in the construction industry. Over the years, the company has implemented a wide range of projects, from simple to complex structural solutions, and performed professional supervision.