Features of the Stress State of Composite Reinforcement during Tensile Tests

The purpose of the work is to establish the characteristics of the stress state of composite building reinforcement during tensile tests, caused by errors in the centering of the composite rod when installed in anchor couplings. A calculation scheme and a corresponding differential equation describing the stress-strain state of the rod have been compiled. Analytical dependencies were obtained to determine the bending moment and the stresses caused by it. A calculation estimate of bending stresses was made in comparison with the nominal tensile stresses of the rod. It is shown that bending stresses are unevenly distributed along the length of the rod and reach their highest values near the ends of the test couplings. Bending stresses increase in proportion to the eccentricity of the installation of the rod in the test anchor couplings and decrease with increasing length of the rod working part. Using the example of fiberglass reinforcement with a nominal diameter of 6 mm, manufactured in accordance with СТБ (STB) 1103–98, a calculation estimate of these stresses was made for a wide range of changes in the eccentricity of the composite rod in the anchor couplings location and the length of the working part of the test sample. It is shown that the use of short samples should be accompanied by an increase in the accuracy of rod centering in test anchor couplings. A method convenient for engineering calculations is proposed for determining bending stresses and total stresses in a composite rod. The research results can be used in engineering practice and in the educational process when training specialists in construction and chemical technology.