Based on the results of A. D. Rzanitsin and V. D. Raizer in the references of [l] and [2], this paper gives other definitions of the confidence level of subjected loads f3s and the confidence level of the strength of materials f3R, then studies the relationship between the load factor k, the material factor and the safety factor nin the traditional models with the factors of f3s, f3R and (3 in the random models in the structural design. | Vietnam Journal of Mechanics, NCST of Vietnam Vol. 23, 2001, No4 (216 - 223) RELIABILITY - SAFETY SET OF STRUCTURES LE XUAN HUYNH , Do VAN BINH University of Civil Engineering ABSTRACT. Based on the results of A. D. Rzanitsin and V. D . Raizer in the references of [l] and [2], this paper gives other definitions of the confidence level of subjected loads f3s and the confidence level of the strength of materials f3R, then studies the relationship between the load factor k, the material factor m and the safety factor n in the traditional models with the factors of f3s, f3R and (3 in the random models in the structural design. The research results show that physical meaning of two factors of f3s, f3R is the same as the factors of k and m, however it gives more clearly assessements on effects of the over load state and the material inhomogeneous state of the safety working state of the structures. Since the reliability - safety set is also determined from the research results . Some numerical examples are carried out to show the relationship between these above factors. 1. Introduction The structural analysis by the ordinary models has been based on the safety factor n > 1, which is combined by many factors such as loads , materials and working states of the structures. However , two main factors are accounted in determining the safety factor n, that are the factor k > 1 which is called as the overload factor and the factor m 0. (2 .3) For example, in the analysis of the strength of the structures, R is the design strength of the structural member and S is the design stress in the structural member. In fact, R and S are the random variables , therefore M must be a random value. In the analysis of the structures by the random models , Mis seen as the normal distribution shown in Fig. 1. M M Safety level of the structures is assessed by the probability of P(M ~ 0) which is corresponding to the area limited by the curve and two positive axes. The area with
