Despite significant advances in structural materials, catastrophic beam-column joint failures in reinforced concrete (RC) buildings persist in being a problem during earthquakes. The behavior and failure mechanisms in RC joints have been extensively studied in the past and are well understood under simple (planar) loading conditions. Current practice tells us to increase the joint dimensions or the amount of reinforcing steel to enhance the capacity of the joints and prevent premature failure. However, this approach is definitely not sustainable. Additionally, as observed in recent earthquakes, this practice does not always prevent catastrophic failures in the joint region, leading to the conclusion that the behavior of joints under complex (multi-axial) loading conditions is still not well understood.
In this project, high-performance fiber reinforced concrete (HPFRC) will be selectively used at the beam-column joints to improve the structural performance of buildings while keeping the additional costs at a minimum. Using experimental and computational methods, a comparative damage evaluation and life-cycle cost assessment of building with RC and HPFRC joints will be conducted. Analysis of joints is a difficult task because of the complex load transfer and the behavior of materials under multi-axial loading. Therefore, two multi-axial (6 degree-of-freedom) loading units will be used to impose realistic loading and boundary conditions on the joints, and a digital-image correlation system for non-contact deformation measurements (DIC) will be used to obtain full-field 3-D strain maps to study critical deformation states that lead to the initiation of damage as well as its progression until complete failure. These research activities are anticipated to yield critical new knowledge and understanding of the behavior of RC and R-HPFRC joints, and reliable computational tools to study the RC/reinforced-HPFRC material and joint behavior.
Broader Significance and Importance
The proposed novel approach is expected to transform the design and construction of RC beam-column joints over the long-term. A direct benefit of this project to society is the improvement in public safety in response to earthquakes. An additional benefit is increased sustainability in the form of reduced direct and indirect economic losses and environmental impacts. The achievements in this project will be a large step in reaching the ultimate goal of resilient and sustainable civil infrastructures. The proposed joint concept also has broad applicability in other types of concrete construction, including offshore and nuclear structures. The data collected from these novel testing and measurement approaches will serve as benchmarks for the development of new theories for numerical modeling and engineering simulations, which could not be considered previously because of the lack of supporting experimental data.
Broadening Participation Activities
The University of Houston (UH) is a Hispanic-Serving Institution. The UH student body of nearly 40,000 students is one of the most diverse in the United States. Educational modules will be developed and introduced in three courses to influence the education of more than 100 students per year. Because of the inherent campus diversity, these educational initiatives will naturally reach a diverse audience. Graduate and undergraduate students will be recruited from underrepresented groups. In collaboration with a local high school with more than 90% underrepresented students, a field trip will be organized every year for 25 students to visit the UH campus and participate in hands-on training. In addition, one high school teacher will be recruited every summer to gain exposure to research activities and help develop a course module for high school physics courses. Through the developed education activities, high school teachers, high school students, and undergraduate and graduate students will have an opportunity to interact and learn from each other. The course modules will directly derive from the research findings and be implemented in high school and college level courses, thereby naturally integrating research and education.
This research has been funded through the Broadening Participation Research Initiation Grants in Engineering solicitation, which is part of the Broadening Participation in Engineering Program of the Engineering Education and Centers Division.
