The paper provides a solution to the problem of dimensioning decisive bars on the basis of the conditions of meeting the recommended reliability classes [9] of statically determinate structures composed of n members. A theorem was formulated: if a statically determinate structure composed of n decisive members is to attain the reliability greater than, or equal to, the recommended reliability p = 1- q, it is necessary and sufficient that the damage frequency sum qi of decisive members is smaller than the admissible damage frequency q of the structure: Σqi < q. On the basis of this theorem, s coefficients that recommend increase of the load bearing capacity of the decisive bars in a statically determinate structure constructed in order to meet the recommended class [9] of the structure reliability, are estimated and presented in a tabular form.
