GOALI: Development and Evaluation of Innovative FRP Braided Fabric for Strengthening Infrastructures

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CMS 9906404PI: Nabil F. GraceDevelopment and Evaluation of Innovative FRP Braided Fabric for StrengtheningInfrastructuresThe use of fiber reinforced polymer (FRP) sheets and strips as strengtheningmaterials for concrete structures has been gaining the interest of manyresearchers and a few contractors during the last two decades. However, thelack of ductility in these materials and the corresponding catastrophicfailures of strengthened structures reported in several research investigationshave contributed to the lack of confidence in composite materials forstructural engineering and the subsequent delay in using them for thestrengthening/stiffening of concrete structures in the United States. It hasbecome impossible to convince practicing structural engineers to recommend theuse of these materials to their clients. This is to be expected, sincestructural engineers are very conservative and are accustomed to structuresthat dissipate considerable energy before failure. Since ductility, combinedwith the safety of occupants, is the basic ingredient of any successfulstrengthening/stiffening project, only a handful of contractors has consideredthe use of FRP materials. As a result, the use of currently available FRPmaterials in strengthening or stiffening applications in industrial facilitiesand highway bridges has been very limited in the United States.To solve this problem, an innovative design of new FRP sheets needs to beintroduced and evaluated in both laboratory and field. This will requireextensive collaboration among: (1) FRP fabricators (i.e., composite industrythat includes both producers of carbon, aramid, and glass fibers and epoxyadhesives), (2) contractors (construction industry), (3) academia, and (4) endusers (structural engineers). The proposed study will be conducted withcollaboration among Lawrence Technological University (LTU), DFI PultrudedComposites (DR), Baker Concrete Technologies Ind. (BCT), and Ohio Department ofTransportation (ODOT).The study will consist of four phases. The first phase will address thedevelopment of an innovative threeaxis braided FRP fabric that will befabricated using a combination of carbon, aramid and glass fibers oriented inthree different directions. These sheets will differ from the currentlyavailable, ineffective unidirectional and woven single fiber-type sheets, whichhave been evaluated at LTU and found to lack the necessary energyabsorbingcapability. The developed fabrics will provide ductile rather than brittlefailure of strengthened structures. The interlocking mechanisms between thebraided carbon, aramid, and glass fibers in the three axes will ensureredistribution of the flexural and shear loads. This phase will also includethe determination and optimization of the mechanical properties of the braidedsheets and a selected epoxy adhesive. This phase will be completed by DFI andLTU.The second phase will deal with the construction, instrumentation andstrengthening of simple, continuous, and cantilever test beams. The developedFRP braided fabric and the selected epoxy adhesive will be used forstrengthening these beams. This phase will be completed by collaborationbetween the FRP producer, LTU, and the contractor. In the third phase, thestrengthened test beams will be transported to the Structural Testing Center(STC) at LTU and the research team will conduct various environmental/loadingtests. During phase four, results from the first three phases will be deployedinto a practical application in the state of Ohio by ODOT.This collaboration will be extended to teaching and seminar activities. The FRPproducer, strengthening contractor, and state engineers will be guest lecturersat LTU. The university research team and the industrial partners will provideseminars at the annual meetings of the Associated General Contractors ofAmerica (AGC) and at meetings of the Great Lakes DOTs Consortium. Collaborationbetween university and industry will result in the development of an innovativeFRP material for strengthening deficient concrete structures. The level ofconfidence achieved by these activities win lead to the widespread use of thisstateofthe art technology.