## 5 Conclusions
If the thermal model has finite contact conductance for a contact pair, a temperature drop can occur across the pair, and users should ensure that temperatures from one side of a contact pair do not end up on the other side. An identical mesh helps to avoid convergence issues. 2. A bonded contact with variable thermal properties was used in the numerical model because the embossments of the steel decking significantly reduce the sliding between the concrete and the steel decking. As shown in Section 3.1, numerical and experimental results are in good agreement. 3. The numerical models developed simulate the effect of the endothermic process of free water vaporization, showing slope changes around 100 \({}^{\circ}\)C. At the end of the FEM model, around 1500 s, there is some divergence between experimental and numerical results. These differences could be due to the debonding effect that occurs in the experimental tests. 4. The definition of a thermal contact conductance coefficient as a function of temperature is needed to obtain a good agreement between numerical and experimental results. 5. The mechanical properties must be defined as a function of temperature. This nonlinearity makes it possible to simulate structural behavior under fire conditions. 6. The validation of the numerical models is possible by defining thermal expansion. The correct definition of this parameter plays a fundamental role in ensuring that the coupled models follow the experimental evolution. The use of the values indicated in Eurocode 4 part 1-2 causes errors. These errors include a 30% discrepancy between experimental and numerical data, as well as the non-convergence of the model. 7. Differences between experimental and numerical temperatures at the thick part are attributed to the convection coefficient for the web of the steel decking. This value, taken from a previous work [42], does not take into account the vaporization phenomenon at the interface between steel decking and concrete. Future research works should be expanded to properly define this convection coefficient. 8. The use of different static structural analyses with a transient thermal analysis makes it possible to simulate the experimental structural behavior of composite slabs under fire conditions. The numerical model presented in this work is capable of accurately reproducing the structural behavior of the composite slabs after 500 s of testing, when the debonding has already happened. Until then, there are significant discrepancies between the experimental and numerical results, due to the complexity of the thermal and mechanical phenomena that occur in this phase. * In general, the proposed values of the thermal contact conductance coefficient provide good agreement with experimental results and satisfactorily simulated the debonding effect. However, the numerical results include a significant discrepancy between experimental and numerical data up to 500 s of normalized test time. Future works should study new coefficients as mentioned by [PERSON] et al. [24]. Conceptualization, J.J.d.C.-D.; methodology, F.P.A.-R.; validation, F.P.A.-R.; investigation, F.P.A.-R.; data curation, J.E.M.-M.; writing--original draft preparation, J.E.M.-M.; writing--review and editing, M.A.-M.; visualization, J.E.M.-M.; supervision, J.J.d.C.-D.; funding acquisition, J.J.d.C.-D. All authors have read and agreed to the published version of the manuscript. This research was funded by Ministry of Science, Innovation and Universities of Spain, under project with funding number PGC2018-098459-B-I00, co-financed with EU FEDER funds. Furthermore, the authors also thank the regional funders through the Asturian Government and the Foundation for the Promotion in Asturias of Applied Scientific Research and Technology (FICYT), co-financed with EU FEDER funds under Research Project with funding number AYUD/2021/51328. Not applicable. The authors declare no conflict of interest.