The aim of the study is a probabilistic analysis of a steel truss bridge. Structural design parameters were defined as deterministic values and random variables. The latter were not correlated. In the reliability analysis two variants of the description of random variables were considered. In the Variant I the normal distribution was used whereas in the Variant II – different types of probability distribution appropriate for the nature of the variable were proposed. The transformation of normal parameters into the parameters of another distribution was estimated by collocation method at the central point. The criterions of structural failure were expressed by a limit function related to the serviceability limit state and ultimate limit state. The module for symbolic computation using the Finite Element Method was created in the Mathematica software and used to define limit functions for different load schemes. These functions were the starting point for the probabilistic analysis for which the reliability software STAND was used. The Hasofer-Lind reliability index was estimated using the FORM method. In addition, the study presents graphs of sensitivity of the reliability index to the random variables.

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