Optimizing the Strengthening Efficiency of Double Skin Tubular Beams using Sustainable Hybrid LRS FRP System

The efficiency of utilizing a hybrid strengthening system composed of sustainable material was examined in this study using the nonlinear finite element analysis (NLFEA) method. The flexural behavior of double skin tubular beams (DSTB) of rectangular cross section was investigated. Beams were composed of inner hollow circular steel tubes of finite thickness and strengthened with sustainable FRP material with improved ductility due to its large rupture strain (LRS) characteristics. In this study, three strengthening systems are investigated, and their efficiency is presented to help engineers optimize their design in terms of weight, cost, ductility, strength, and sustainability. The three systems were as follows: the first is composed of a laminate positioned at the tensile fiber of the beam in the longitudinal direction, the second one is a wrapped FRP covering the whole beam perimeter and length, and the final one is a hybrid system combining the laminate and the wrapped LRS FRPs. Results will be presented and compared to reach clear conclusions regarding the optimized use of the LRS FRP in improving the flexural behavior of DSTBs.