The Structural Behaviour of Tension Steel Rods Strengthened with Carbon-Fiber-Reinforced Composite Materials

Abstract

Strengthening can increase or recover the bearing capacity of steel constructions of buildings and structures in operation. Besides well-known strengthening techniques, including an increase in the sectional area by means of attaching steel plates, angles, channels, pipes etc. to a strengthened element, other methods, that involve the use of carbon fiber-reinforced composite materials, have strong prospects. So far, the structural behaviour of steel constructions, strengthened with carbon fiber-reinforced composite materials, is understudied, and this fact restrains the practical application of this strengthening method. The article presents the results of complex experimental, theoretical and numerical studies of the features of the operation of steel-stretched elements reinforced with glued carbon fiber. The emphasis is on the load-bearing capacity of the reinforced element, and not on the mechanism of destruction of the glue. This is due to the use of an adhesive joint performed using the glue and gluing technology recommended by the manufacturer of carbon fiber. It has been experimentally established that, in this case, the stresses in carbon fiber cannot exceed a certain value. Theoretical dependences for the calculation of CFRP-reinforced steel stretched elements are proposed. The scientific novelty of this research project is a set of basic principles and methods, developed to identify the bearing capacity of steel rods, strengthened with carbon fiber-reinforced composite materials, taking into account the joint strength performance of a steel rod and adhesively bonded carbon-fiber-reinforced composite material, as well as the new findings thus obtained, such as the theoretical dependencies needed to identify the bearing capacity of steel rods strengthened with carbon-fiber-reinforced composite materials; experimental data on the joint strength performance of carbon-fiber-reinforced composite lamellas attached to a steel rod by an adhesive; experimental data on the performance and the bearing capacity of steel rods strengthened with carbon-fiber-reinforced composite lamellas; development of finite element models of steel rods strengthened with carbon-fiber-reinforced composite materials, and computational studies of steel rods strengthened with carbon fiber-reinforced composite materials.