Fire Analysis of Slim Floor Systems using Cofradal Floor Units

Shallow composite floor beams – Proposal of a simplified analytical method for standard fire rating

“…The model presented in [18] seems to be consistent with this observation, as a temperature gradient is considered between the two parts. Figure 3 Temperature in the bottom flange: results "WRFC50522" / "WFRC52897" "TNO1995" [24] and comparison with analytical methods [27][18] [15] As expected, the temperature of the weld between the bottom plate and the lower flange reaches quickly the temperature of the bottom plate, and after 60 minutes of ISO fire exposure the difference is less than 10%. Therefore, the approach of a weld temperature equal to the temperature of the bottom plate seems justified.…”

“…This modification has been implemented by the observation of the experimental and numerical results.  The temperature of the web is assumed as constant and calculated according to the model [27] at a distance equal to ¼ of the web height from the bottom flange. This simplification allows for an easier model for the calculation of the sagging moment resistance with an imprecision which is considered acceptable since the web contribution to the bending moment is minor.…”

“…The reduction factor has been calculated for the most severe cases amongst the 310 configurations considered in the numerical study by assuming a temperature distribution according [27], applying the corresponding strength reduction factor according [22] and by integrating the residual resistance.…”

“…The thermal model is based on Zaharia-Frannsen [27], Romero-Cajot [35], [28], Hanus et al [38], with some adaptations to ensure consistency of results within the given field of application.  The formula for the bottom plate with a limitation of the plate thickness to 40mm is used (for ep > 40mm the model shows some inconsistencies and needs to be limited, see Cajot et al [30]);  For the calculation of the temperature of the bottom flange the formula proposed by Romero-Cajot [35] , [28] is used.…”

“…This paper aims at filling this gap by proposing to practitioners a simple tool, which addresses specifically the Slim-Floor beam typology. The presented method is based on thermal models existing in the literature, mainly Zaharia, Franssen et al [27], and Hanus et al [38], and completed with a comprehensive analysis of tests and enlarged by a broad parametric study.…”