Self-Stressing Shape Memory Alloys/Fiber Reinforced Polymer (SMA/FRP) Composite Patches for Rehabilitation of Cracked Steel Structures

本项目的目的是研究使用新型的“自应力”复合补片来修复此类开裂的钢结构。 桥梁等钢结构在反复荷载作用下容易产生疲劳裂纹。 这些裂缝随着时间的推移而增长，如果不加以控制，它们可能会损害结构的完整性，甚至可能导致结构的完全倒塌。 补片由纤维增强聚合物复合材料制成，并嵌入形状记忆合金股线，从而提供补片的自预应力特性。 修补将使用结构粘合剂粘合到开裂的钢结构表面，以提高加固结构的疲劳寿命。 为实现这一目标，该项目将分三个阶段进行。 在第一阶段中，将测试一系列形状记忆合金复合材料补片，以评估不同参数对补片预应力特性的影响。 第二阶段将包括测试小规模和大规模的裂纹结构构件与补丁加强，以量化疲劳寿命的增加，可以实现在钢结构。 在第三阶段，将开发一个数值模型来预测使用自应力补片修复的开裂钢构件的行为。 该项目的成功将导致开发一种创新的新方法来修复开裂的钢和其他金属结构。 该项目还将建立一个数值框架来预测加固结构的行为。该项目开发的加固裂纹结构的方法在包括海洋、航空航天和海上能源结构在内的多个领域具有广泛的应用。 研究成果将通过编制课程单元、在国家和国际会议上介绍以及在档案技术期刊上发表而广泛传播。 该项目将通过研究生参与项目研究工作，为他们提供高级培训。该研究团队将与休斯顿大学现有的外展计划密切合作，招募研究生，并为传统上代表性不足的群体的学生提供指导。 该研究小组还将与现有的NSF支持的外展计划进行对接，为高中学生和教师提供教育机会和教学材料。

The objective of this project is to investigate the use of novel "self-stressing" composite patches to retrofit such cracked steel structures. Steel structures, such as bridge girders, are susceptible to fatigue cracking under the effect of repeated loading conditions. These cracks grow with time and if unchecked they can compromise structural integrity and potentially even lead to complete collapse of the structure. The patches are made of fiber reinforced polymer composites with embedded shape memory alloy strands which provide the self pre-stressing properties of the patches. The patches will be bonded to the surface of cracked steel structures using a structural adhesive to enhance the fatigue lives of the retrofitted structures. To achieve this objective, the project will be conducted in three phases. In the first phase, a series of shape memory alloy composite patches will be tested to evaluate the effect of different parameters on the patch pre-stressing characteristics. The second phase will consists of testing small-scale and large-scale cracked structural members reinforced with patches to quantify the fatigue life increase that can be achieved in steel structures. In the third phase, a numerical model will be developed to predict the behavior of cracked steel members that are repaired using the self-stressing patches. The success of this project will lead to the development of an innovative new approach for repairing cracked steel and other metallic structures. The project will also establish a numerical framework to predict the behavior of the retrofitted structures.The approach developed in this project to retrofit cracked structures has broad applications in several fields including marine, aerospace, and offshore energy structures. The research results will be broadly disseminated through the development of course modules, presentation at national and international conferences, and publication in archival technical journals. The project will provide advanced training to graduate students through their involvement in the project research work. The research team will work closely with existing outreach programs at the University of Houston to recruit graduate students, and provide mentorship to students from traditionally under-represented groups. The research team will also interface with existing NSF-supported outreach programs to provide educational opportunities and instructional materials to high-school students and teachers.