Mathematical analysis of an innovative method for strengthening concrete beams using pre-stressed FRP laminates

Paper in proceedings, 2018

This paper presents mathematical modeling and analytical solution of an innovative method for strengthening of flexural concrete members using pre-stressed carbon fiber reinforced polymer (CFRP) laminates without the need for mechanical anchorage. Bonding CFRP laminate in a pre-stressed state to the tensile part of flexural members is an effective method to improve their bending performance. The elimination of end anchors is found to be possible by using an innovative pre-stressing device capable of creating a step-wise decreasing profile of pre-stressing force towards each end of the CFRP laminate. The proposed innovative pre-stressing device consists of a multiple of aluminum tabs interconnected by steel bars having different diame-ters. The pre-stressing force is applied to the end tab and evenly distributed among all tabs. Each tab is me-chanically fastened to the CFRP laminate. Two 10-mm-thick GFRP plates are used as force-transfer medium to connect the pre-stressing device to the CFRP laminate. An efficient mathematical modeling of the innova-tive system is developed and corresponding governing equations are solved analytically. A comparative study is conducted between the stress and displacement results of the step-wise pre-stressing method and that of conventional methods where pre-stressing is performed in one step.