## 5 Conclusions  
In the article, a specific calculation example was analyzed, but the conclusions have universal character and can be referred to for many other structures, mainly for steel trusses. The results presented in the article indicate unambiguously that the probabilistic model has a significant influence on the results of the reliability analysis. The preparation of the probabilistic model is the biggest challenge and the most difficult task during the safety analysis of a structure. It is not obvious which values should be treated as probabilistic and with which characteristics. This problem is especially evident during the analysis of the structure under fire conditions. The authors of the presented paper managed to solve the problem with the probabilistic character of the buckling coefficient of an element under fire influence. The meaning of the appropriate choice of this coefficient has already been analyzed in the paper [48]. A computer code was prepared that allows the user to obtain the'real' coefficient of the variation of bearing capacity as a result of computation with any input probabilistic variables. The proposed method is an alternative method to the approximation method using Equation (28). Using the method proposed by the authors, the reliability index is lower, so the results are safer, but it is worth considering if it is not too conservative. It raises a question: Is it possible to change profiles (cross sections) and as a result to reduce the total cost of the structure? The answer is not so easy, because there are still some aspects that need to be analyzed in following work. Especially:  
Figure 10: Representative \(\alpha_{i}\) for random variables (advanced model).  
* The trial to conduct the experiments to find out what the true changes of material characteristics in the steel under fire influence are.
* The analysis of the steel truss with more types of loads with different distribution types.  
In the paper, the authors used reliability analysis, connected with the FORM method, which can be easily done using special software. In this article, it was the SYSREL program. The most difficult part during system analysis is searching cut-sets, but the author-prepared C++ code enables us to find it effectively.  
In summary, it should be said that system reliability analysis for truss elements can be successfully used for a structure under fire influences or in persistent design situations, but there are still some problems to solve and issues to develop. The presented paper is the part of wider research which will be continued in the nearest future. Especially, the authors are going to develop and refine the proposed algorithm. Its usefulness for another structures, including spatial trusses, will be tested.  
Conceptualization, K.K. and M.S.; methodology, K.K; software, K.K.; validation, K.K. and M.S.; formal analysis, M.S.; writing--original draft preparation, K.K.; writing--review and editing, M.S.; visualization, K.K.; supervision, M.S. All authors have read and agreed to the published version of the manuscript.  
The APC was funded by the program of Minister of Science and Higher Education \"Regionalna Iniciatytoa Doskonalosci (RID)\" No. 025/RID/2018/19 of the day 28 December 2018.  
Not applicable.  
The authors gratefully acknowledge the contribution of the Scientific Grant Agency of the Slovak Republic under the grant VEGA no. 1/0230/22.  
The authors declare no conflict of interest.