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.