Eat safely on the Titlis

The existing radio tower on the Titlis is being converted into a restaurant and bar. For this purpose, it is planned to add two load-bearing volumes to the existing structure via a steel framework. A temperature simulation based on a natural fire method has been carried out for both volumes, hereinafter referred to as boxes. On the basis of these simulated temperature effects, a hot temperature measurement was carried out for the restaurant box to determine sufficient fire resistance - in a first step in 2019 and in a second step again in 2023 due to project changes to the steel structure.

The hot design is divided into a numerical thermal analysis to determine the component temperatures in the event of fire and a numerical mechanical analysis for the actual verification of the load-bearing capacity in the event of fire.

Due to the high component temperatures in the middle section of the restaurant box façade, i.e. the clamping area of the cantilevered supporting structure, and the associated drop in stiffness and strength, the supports and diagonals of the façade truss in this area hardly contribute to the load-bearing effect. However, due to the high temperatures, these components exert high constraining forces on the edge beams above and below. In addition to the constraining forces arising from the temperature load, the edge beams must therefore take on the majority of the load-bearing capacity in the clamping area. Taking into account the redistributions in the supporting structure during the course of the fire, the components are designed for the stresses that occur in order to maintain the necessary stability and robustness of the supporting structure in the event of a fire. The steel structure of the restaurant box is able to stably absorb the load in the event of a fire without load redistribution from the restaurant box to the existing supporting structure of the tower for the assumed fire scenario.

The steel structure of the restaurant box in the former radio tower of the mountain station has sufficient fire resistance for the fire scenario. The fire resistance period exceeds the self-rescue phase required by the protection target. No additional fire protection measures are required for the steel structure of the restaurant box or the tower.

Services

• Natural fire simulation
• Numerical thermal analysis
• Numerical mechanical analysis

Design of the supporting structure in the event of fire

Overall Titlis project: https://www.gruner.ch/de/projekte/titlis

Pictures: Herzog & de Meuron Ltd, Gruner AG

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