Effect of nanocomposites on the dynamic properties of repaired flexural elements

Abstract

Application of modern techniques to rehabilitate structural elements due to aging and/or flexural cracks is of great concern by many researchers. In the current research, high strength epoxy matrix incorporated Carbon Nano Tubes (CNT) was used to bridge up the gaps in the vicinity of flexural cracks. First, the physical properties of CNT were studied followed by mechanical examination of the epoxy resin with/without CNT. The dynamic behavior of simply supported concrete and steel beams, as well as a cantilever steel beam was investigated. All the examined beams were excited by a light impact hummer at their sound, cracked, and repaired states. The free vibration response was collected, processed and the modal parameters were obtained. The change in the dominant natural frequency and damping ratio were investigated in each of the examined condition. The degradation in the beams was created by generating synthetic cracks at the locations of maximum bending moment using a saw cut. Furthermore, intensive numerical finite element modelling (FEM) was carried out using (ANSYS). The obtained numerical results were of great coincidence to the experimental work. It was concluded that the use of epoxy matrix containing CNT enhanced the dynamic properties of the cracked beams and was able to restore the integrity of the beams to a condition slightly the same as their original sound states. Keywords: Dynamic parameters, FEM, Strength recovery, CNT, Epoxy, Rehabilitation