EXPERIMENTAL STUDIES OF THE WORK OF NAILED CONNECTIONS

This study is devoted to one of the most common types of wooden structural elements joints - nailed connections. The article presents the results of experimental studies of two types nailed connections on metal plates: traditional connections without bushings and connections, reinforced (modified) with pressed-in fiberglass bushings. The methods of mathematical planning of the experiment were used during the test. That allowed to significantly reduce the number of tested samples of connections and to obtain mathematical dependences in the form of response functions for such characteristics as breaking load Nt and load NI-II, corresponding to the upper boundary of the elastic behavior area of the compound from three factors: the angle between the direction of the acting force and the direction of the wood fibers, the dowel diameter and the wall thickness of the fiberglass bushing. The obtained dependences allow us to evaluate the values of the loads Nt and NI-II for the nailed connections with bushings without testing.According to the experiment planning matrix, 15 types (series) of connections with pressed-in fiberglass bushings and 9 types (series) of traditional nailed connections without bushings were tested.According to the test results, the authors made a comparison of the load bearing capacity and deformability of two types of nailed connections, with bushings and without bushings; the nature of the damage has been established; the analysis of stress-strain state of the middle wooden element in the area of mortise strengthened with pressed-in fiberglass bushing is performed; the conclusion about prospects of application of a pressed-in fiberglass bushings to enhance mortises of new structures and when reconstructing wooden structures in operation.