Наука и техника (Mar 2017)
PROBABILISTIC ASSESSMENT OF NECESSITY IN REPAIR AND ITS TYPE FOR BUILDING AND ITS ELEMENTS
Abstract
The existing normative documents consider 100%-wear as an extreme limit for operation of constructional element or structure. While using probabilistic rate of physical wear and determining the necessity in repair 100%-wear is assumed on the basis of physical state of constructional elements and structures that corresponds to minimum allowable reliability level. The paper contains description of a new method for determination of necessity in repair and its type for building and its elements on the basis of probabilistic assessment of their physical wear which is mated with residual reliability. Such method of calculation is carried out by determination of initial and threshold limit values for failure or destruction probabilities and density of probability distribution. According to these values time wear rate is selected and it ensures higher specific growth of failure and destruction probabilities at initial running period of the element operation. Then a planned wear assessment of building elements is carried out on a periodical basis. In the case when the planned rate of probability growth is equal to 0.4–0.5 from the critical value it is necessary to execute a mean current repair and when the probability level reaches value of 0.8 or even more in comparison with a critical one then it is necessary to carry out a capital repair in order to reduce probability value which will be close to the initial one. Such planned assessment of physical wear is made according to regulatory indirect indicators and in the case when intensity of physical wear exceeds the planned level it is necessary to determine strength characteristics of building elements while using instrumental physical methods. Taking into account a relative novelty of probabilistic assessment of necessity in repair and its type for building and its elements during operational period it is recommendable to carry out additional theoretical and statistic investigations in order to include this method in normative technical construction documents.
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