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

CMS 9906404PI：Nabil F.Grace用于加固基础设施的新型FRP编织布的开发和评价在过去的二十年里，纤维增强聚合物(FRP)片材和带材作为混凝土结构的加固材料引起了许多研究人员和少数承包商的兴趣。然而，这些材料的延展性不足，以及几项研究报告中报告的加固结构的相应灾难性失效，导致对结构工程用复合材料缺乏信心，随后在美国将其用于混凝土结构的加固/加固方面的延迟。要说服执业结构工程师向他们的客户推荐使用这些材料已变得不可能。这是意料之中的，因为结构工程师非常保守，习惯于结构在失效前消耗相当大的能量。由于延性，加上居住者的安全，是任何成功的加固/加固项目的基本要素，只有少数承包商考虑使用FRP材料。因此，在美国，目前可用的玻璃钢材料在工业设施和公路桥梁的加固或加固应用中的使用一直非常有限。为了解决这个问题，需要在实验室和现场引入和评估新型玻璃钢板材的创新设计。这将需要以下各方的广泛合作：(1)玻璃钢制造商(即复合材料行业，包括碳纤维、芳纶、玻璃纤维和环氧胶的生产商)，(2)承包商(建筑业)，(3)学术界和(4)终端用户(结构工程师)。这项拟议的研究将由劳伦斯理工大学(LTU)、DFI PultrudedComposites(DR)、Baker混凝土技术公司合作进行。(BCT)和俄亥俄州交通部(ODOT)。这项研究将包括四个阶段。第一阶段将开发一种创新的三轴编织玻璃钢织物，这种织物将使用碳、芳纶和玻璃纤维的组合在三个不同的方向上进行制造。这些片材将不同于目前可用的、无效的单向和机织单纤维类型的片材，这些片材已经在LTU进行了评估，发现缺乏必要的能量吸收能力。开发的织物将提供韧性而不是脆性，以防止加固结构的失效。编织的碳纤维、芳纶和玻璃纤维在三个轴上的联锁机构将确保弯曲和剪切载荷的分配。这一阶段还将包括测定和优化编织片和选定的环氧胶的机械性能。这一阶段将由DFI和LTU完成。第二阶段将处理简单、连续和悬臂试验梁的建造、检测和加固。开发的玻璃钢编织布和选定的环氧胶将用于加固这些梁。这一阶段将通过玻璃钢生产商、LTU和承包商之间的合作完成。在第三阶段，加固试验梁将被运送到LTU结构试验中心(STC)，研究小组将进行各种环境/载荷试验。在第四阶段，前三个阶段的成果将由Oott推广到俄亥俄州的实际应用中，这种合作将扩展到教学和研讨会活动。FRP生产商、加固承包商和国家工程师将担任LTU的客座讲师。大学研究团队和工业伙伴将在美国联合总承包商(AGC)的年度会议和五大湖DOTS联盟的会议上提供专家意见。大学和产业界的合作将导致一种创新的FRP材料的开发，用于加固有缺陷的混凝土结构。这些活动所达到的信心水平导致了这种先进技术的广泛使用。

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.