In the course of the repair and fire protection upgrading of an approx. 1100 m long road tunnel in Hamburg, the eleven crossings of fire protection channels were covered with sheet steel to prevent the nesting of pigeons. In this context, the mechanical strains that may occur in the event of a fire had to be determined. In particular, it was necessary to clarify which mechanical loads would result from relative movements between the substrate (fire protection board) and the cover sheets due to their different thermal expansion in case of fire. For this purpose, the thermal behavior of the CSH fire protection board was determined by means of simultaneous thermal analysis and dilatometry, and the mechanical and thermal behavior of the composite construction was studied. The studies revealed that due to the facts that thermal expansion of the both materials and due to the softening of the fire protection panel the restraint that is generated by the screwed-on perforated plate in the vicinity of the screw shafts remains low during thermal loading. As a result, the top plate does not crack or break off, which means that screwing on the perforated steel sheets not negatively affects the fire protection of the panels.
