Reliability estimation of industrial building structures
The article is devoted to solving the problem of the reliability of industrial building structures: crane and roof beams, columns, redundant building systems. For this aim, the probabilistic method of structural reliability estimation is developed after the criterion of bearing strength, in which the main component of structure reliability is faultlessness. The method takes account of the random loads and material strength, loads joint action, the specific character of work and failure elements, nodes and the whole structure as well. For the ground of method, the large amount of statistic results on crane load is examined for the bridge cranes of the different types. A large amount of wind and snow meteorological data is collected for the territory of Ukraine. Stationary probabilistic model of crane load and quasi-stationary model of the snow and mean wind load are substantiated. The most widely spread probabilistic presentations of random loads are observed. They are as follows: stationary random process and its absolute maxima, random sequence of independent and correlated loads, discrete presentation and extreme model. It was deduced that the redundant structure reliability estimation is a very complicated problem as depends upon the system complexity. The method of states, a probabilistic method of ultimate equilibrium and logic and probabilistic method are developed for solving this problem. On the base of the determined method, the numerical reliability computations of a wide range of industrial building structures are realized. It is shown that the structures have quite different levels of reliability. In particular, the light roof structures are not reliable enough being under the great influence of snow load. At the same time, the Design Code allows over-estimation of reliability for industrial columns. The estimation of industrial redundant structures with a different degree of redundancy is obtained on the base of developed approach. It gave the possibility to evaluate the high safety level of redundant structures in comparison with separate members and statically determined structures. With regard to mentioned results, it is recommended to correct some load factors, a combination factor and a factor for model uncertainties of the Design Codes of structures and loads.