Experimental evaluation of Strength and Deformability of Steel Nails for Wooden Structures

Abstract

Purpose. The main purpose of the paper is to discuss the experimental studies to determine in laboratory conditions the characteristics of nail steel of one of the most common companies on the modern construction market of Ukraine – ExpertFix (Denmark). Methodology. To achieve this goal the tests were carried out for tensile testing of nails of a classic round cross-section of 5 diameters in the range from 4 to 7 mm, manufactured according to the German standard. Findings. According to the results of the study, diagrams of the work of steel nails under load were constructed, which turned out to be very close to the classical diagram of the work of high-strength steel. The destruction of the samples occurred according to a visco-plastic scheme with the formation of a characteristic «neck» at the rupture site. The recorded strength level is from 450 to 700 MPa at a relative deformation of up to 13%. Originality. The obtained characteristics of nails correspond to high-strength steels of classes C390–C500 according to the standard of Ukraine, but do not correspond to steels of grades St1-St3, for which current theoretical approaches to the design of nodal connections have been developed. Therefore, the use of such nail products in practice requires adjustment and clarification of existing approaches and methods of their use in wooden structures, which in turn requires the intensification of scientific research in this direction. Practical value. The practical usage of the strength characteristics of steel nails obtained during experimental studies allows for the correct and reasonable design of nodal connections of wooden structures based on the current Ukrainian standard. It also provides a basis for developing more advanced calculation approaches for assessing their performance.