The lack of ductility in these materials and the corresponding catastrophic failures of strengthened structures reported in several research investigations have contributed to the lack of confidence in composite materials for structural engineering and the subsequent delay in using them for the strengthening/stiffening of concrete structures in the United States.
To solve this problem, an innovative design of new FRP sheets needs to be introduced and evaluated in both laboratory and field. The study will consist of four phases. The first phase will address the development of an innovative three-axis braided FRP fabric that will be fabricated using a combination of carbon, aramid and glass fibers oriented in three different directions. These sheets will differ from the currently available, ineffective unidirectional and woven single fiber-type sheets, which have been evaluated at LTU and found to lack the necessary energy absorbing capability. The developed fabrics will provide ductile rather than brittle failure of strengthened structures. The second phase will deal with the construction, instrumentation and strengthening of simple, continuous, and cantilever test beams. The developed FRP braided fabric and the selected epoxy adhesive will be used for strengthening these beams. During phase four, results from the first three phases will be deployed into a practical application in the state of Ohio by ODOT.