The question of the use of qualification tests of adhesive systems to determine their residual life is considered. The purpose of the study. Testing the hypothesis about the possibility of applying qualification tests of adhesive systems and regression equations to predict the residual life. Methods. Experimental studies of water resistance of adhesive joints, tensile strength along fibers, heat and frost resistance of adhesive joints, and resistance of adhesive joints to delamination were carried out. Results. Based on the test results, data were obtained on the water resistance of adhesive joints, the tensile strength along fibers, the heat and frost resistance of adhesive joints and the resistance of adhesive joints to delamination. The dependences of the limit on the strength of time are obtained. The residual life was calculated using the obtained equations. Discussion. Based on the studies, it was found that the qualification test data of adhesive systems can be used to determine their durability (residual life). In the future, the results of these studies can be applied for widespread implementation and for inclusion in regulatory documents.

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The article describes the use of two-parameter distributions for assessing the residual resource of engineering systems and building structures of buildings and structures. To estimate the residual resource, the authors propose using the Weibull distribution, beta distribution, gamma distribution, and student distribution. Scopes of each distribution are shown. In particular cases, these distributions turn into normal or exponential distributions, which are widely used to estimate the residual resource of building structures and engineering systems of buildings and structures. The authors proposed an algorithm for using two-parameter distributions for a joint assessment of the residual resource of building structures and engineering systems of buildings and structures. In this algorithm, the authors present the parameters by which it is necessary to choose one or another two-parametric distribution. Further, the authors determined how to estimate the element failure rate in the presence and absence of data on the number of failures. The authors also proposed a procedure for assigning the final value of the residual resource when using several distributions at once. The advantages and disadvantages of using two-parameter distributions for a joint assessment of the residual resource of building structures and engineering systems of buildings and structures are given. The authors also proposed ways to further improve it.

Test methods for reinforcing steel is not suitable for fiber reinforced polymer (FRP) rebars because it can cause destruction of the edge zones of the samples. The polymer matrix and fibers are not able to resist compression across the fibers. Existing test methods for FRP rebars do not contain information about the equipment and composition of the adhesive composition. The purpose of the study is to clarify the adhesive composition and design of the FRP specimen anchor. Methods. There were experimental studies of fiberglass reinforcement polymer rebars samples carried out. The following factors varied: the proportion of the components of the adhesive composition; the area of the adhesive contact of the FRP specimen anchor. Results and Discussion. The proportion of epoxy glue and quartz sand providing the test of automatic transmission is determined. The influence of the thread on the inner surface of the FRP specimen anchor on the adhesive strength in the contact zone «adhesive composition-steel» is estimated. A universal three-dimensional model of the centering plug for manufacturing using additive technologies has been developed. Conclusions. The results of the investigation can be used to upgrade the FRP rebars test methods.

Cross-laminated timber (CLT) panels are widely used in the construction of buildings and structures abroad. Regulatory documentation in the Russian Federation does not contain provisions for calculating such structures. The paper considers the method of calculating the floor slab made of CLT panel using the Euler Bernoulli beam theory. General recommendations for the design of cross-glued wood structures are offered, and assumptions of the developed methodology are given. Much attention is paid to the main design characteristics of the bent element. Comparative values of these characteristics from various sources are given. A coefficient is proposed to be used taking into account the features of CLT panels in calculations.