Steel structure for a sports complex — Córdoba

The sports complex needed to be resolved as a single volume with no intermediate columns, spanning 24 metres clear with a 7-metre clear height under the roof, while also housing an intermediate floor designed for a considerable live load. The steel structure had to respond simultaneously to that span, to the additional loading, and to the wind and seismic demands appropriate to a building of this type and occupancy.

Understanding the problem

MV Ingeniería was engaged to develop the structural design and calculations for the complex, in Córdoba, Argentina, based on the architecture and use requirements already defined. The brief called for a building with a 24-metre clear span and a 7-metre clear column height, with an intermediate floor 12 metres wide by 24 metres long, resolved in two spans.

The type of occupancy introduced additional considerations for the load analysis. As the building is intended for intensive sports use with significant public attendance, a specific risk map was produced for the wind load analysis, and the structure's classification for seismic analysis was defined accordingly. The intermediate floor, in turn, had to be sized for a considerable live load, typical of facilities of this kind.

Solution adopted

The structure was resolved using two-pitch steel portal frames with solid-web, variable-depth sections. In the transverse direction, the frames were designed as moment-resisting; in the longitudinal direction, pinned connections were adopted, with stability provided through St Andrew's cross bracing. The gable frames, which are not inherently stable, were stabilised perpendicular to their plane through the same bracing system shared with the main frames, and within their own plane through additional cross bracing.

In sizing the bracing, wind action proved substantially more demanding than seismic action. In the same bracing diagonal and for the same direction of analysis, the tension force induced by wind reached 39.72 kN, compared with 9.79 kN under the equivalent seismic action — a ratio of roughly four to one. This difference set wind as the governing case for the design of the bracing systems.

The intermediate floor was resolved with continuous purlins, supported on an intermediate beam positioned roughly at the midpoint of the 12-metre width. Given the intended use, and the sensitivity of this type of floor to vibrations induced by user activity, a dedicated vibration study was carried out to verify comfort conditions.

The calculations were developed using the Direct Analysis Method, in accordance with applicable CIRSOC regulations, including seismic and snow load actions. Verification was carried out in two successive stages: first at serviceability limit state and, once this was satisfied, at strength limit state.

During the analysis, localised web buckling was identified in the frame columns. This was resolved by increasing the flange thickness over the initial length of the columns, an intervention made possible because all sections for the project are custom-fabricated.

Result

The calculation model was developed in full using RFEM, together with the corresponding technical documentation and drawings.

The resulting structural design achieves the clear span and height required by the architectural brief, incorporates an intermediate floor suited to its intended use, and relies on custom-fabricated sections that made it possible to resolve the localised buckling identified during verification.