CFRP and UHPC: New insights into strengthening reinforced concrete beams under thermocyclic distress

Higher Education Press

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(a) dimension (unit: mm); (b) test setup (unit: mm); (c) loading protocol; (d) failure mode.

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Credit: Ju-Hyung Kim et al.

A recent study published in Engineering delves into the behavior of reinforced concrete beams strengthened with Carbon Fiber Reinforced Polymer (CFRP) and Ultra-High-Performance Concrete (UHPC) under thermocyclic loading. This research, conducted by Ju-Hyung Kim and Yail J. Kim, aims to understand the effects of multi-hazard loading on these strengthened structures, which is crucial for the maintenance and rehabilitation of existing buildings.

Multi-hazards, such as the combination of seismic events and high temperatures, pose a significant threat to the functionality of buildings. Conventional design practices often fall short in addressing these complex loading conditions. The use of CFRP and UHPC in strengthening concrete members has been proven effective, but their performance under thermocyclic distress remains unclear.

The researchers built on a previous experimental study where load reversals were carried out at temperatures ranging from 25 to 175 °C. They developed an analytical approach to quantify the uncertainty in the hysteretic behavior of the strengthened beams. By comparing the responses of a reference model with experimental measurements, they found that the uncertainty index increased with the drift ratio of the beams. At 175 °C, the uncertainty indexes of CFRP-strengthened (CF) and CFRP/UHPC-strengthened (UC) beams reached as high as 0.35 and 0.37, respectively. This increase in uncertainty correlated with a reduction in the energy capacity of the beams.

The study also explored the hysteretic system of the strengthened beams. The adjusted stiffness of the hysteresis loop was found to indicate damage accumulation and deformation resistance. When plastic hinges formed, a large amount of energy was dissipated. Two hysteresis models, mean and regression, were proposed. The mean model was more suitable when the temperature was below the glass transition temperature of CFRP, while the regression model was better for higher temperatures.

Regarding the pinching mechanism, the researchers found that the magnitude of drift ratios had a greater impact on the progression of pinching compared to the retrofit materials. Although the installation of a UHPC jacket was beneficial in maintaining the stable pattern of hysteresis loops at lower temperatures, thermal damage between the concrete substrate and UHPC at higher temperatures affected its performance.

To aid in practical design, the researchers proposed a performance degradation factor. This factor can be used to estimate the degraded energy dissipation capacity of the beams under thermocyclic distress. The values of this factor range from 1.00 to 0.45, depending on the temperature and the retrofit scheme.

This research provides valuable insights into the behavior of CFRP/UHPC-strengthened reinforced concrete beams under thermocyclic distress. The findings can help engineers make more informed decisions when designing and retrofitting structures to withstand multi-hazard conditions, contributing to the safety and durability of buildings in the face of complex environmental challenges.

The paper “Hysteretic Uncertainty and Anomaly Quantification of Reinforced Concrete Beams Strengthened with Carbon Fiber Reinforced Polymer and Ultra-High-Performance Concrete in Thermocyclic Distress,” authored by Ju-Hyung Kim, Yail J. Kim. Full text of the open access paper: https://doi.org/10.1016/j.eng.2024.11.018. For more information about the Engineering, follow us on X (https://twitter.com/EngineeringJrnl) & like us on Facebook (https://www.facebook.com/EngineeringJrnl).

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Journal

Engineering

DOI

10.1016/j.eng.2024.11.018 

Article Title

Hysteretic Uncertainty and Anomaly Quantification of Reinforced Concrete Beams Strengthened with Carbon Fiber Reinforced Polymer and Ultra-High-Performance Concrete in Thermocyclic Distress

 

Vacuum glazing: A promising solution for low-carbon buildings

Higher Education Press

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Credit: Jinqing Peng et al.

A new review article published in Engineering offers a comprehensive look at vacuum glazing, a technology that shows great potential in enhancing energy efficiency in buildings. As buildings account for around 40% of society’s total energy consumption, improving the thermal performance of glazing is crucial for achieving low-carbon building goals.

Vacuum glazing has gained attention for its heat preservation, sound insulation, lightweight features, and anti-condensation properties. The concept dates back to 1913, but it was not until 1989 that researchers in Australia successfully produced vacuum glazing with excellent thermal insulation performance. Since then, significant progress has been made in its development.

The review covers various aspects of vacuum glazing, including fabrication methods, support pillar arrangements, composite structures, research methods, and energy-saving potential. There are three main fabrication methods: the solder glass edge sealing method, the vacuum chamber edge sealing method, and the pump-out edge sealing method. Each has its pros and cons, but the modified pump-out method seems to be the most promising as it can overcome the drawbacks of high-temperature degradation in the glass powder sealing method and insufficient outgassing in the vacuum chamber method.

Support pillars play a vital role in maintaining the vacuum gap and withstanding external pressure. Their arrangement needs to balance mechanical and thermal considerations. Composite vacuum glazing, such as hybrid, triple, and PV vacuum glazing, has also been developed. Triple vacuum glazing can achieve a very low U-value, indicating excellent insulation performance, while PV vacuum glazing can generate clean electricity by harnessing solar radiation.

To assess the thermal performance of vacuum glazing, researchers use analytical, numerical, and experimental methods. These methods help in understanding the heat transfer processes and evaluating the impact of different factors on the U-value, such as the type of glass, vacuum level, and low-E coating emissivity.

The energy-saving potential of vacuum glazing varies depending on building types, climates, and other factors. In severely cold and cold climates, triple vacuum glazing is highly effective in reducing heat loss. In regions with abundant solar radiation, PV vacuum glazing can significantly enhance building energy efficiency. Tinted vacuum glazing is suitable for areas with significant seasonal variations in heating and cooling demands.

However, there are still challenges to overcome. Further studies are needed on the stability and industrialization of vacuum glazing with aerogel support pillar arrays. Also, determining the appropriate control strategy for tinted vacuum glazing and understanding the aging process of vacuum glazing and its composite structures are important for maximizing their energy-saving benefits. Overall, vacuum glazing holds great promise in contributing to the development of sustainable low-carbon buildings.

The paper “Excellent Insulation Vacuum Glazing for Low-Carbon Buildings: Fabrication, Modeling, and Evaluation,” authored by Jinqing Peng, Yutong Tan, Yueping Fang, Hongxing Yang, Aotian Song, Charlie Curcija, Stephen Selkowitz. Full text of the open access paper: https://doi.org/10.1016/j.eng.2024.11.027. For more information about the Engineering, follow us on X (https://twitter.com/EngineeringJrnl) & like us on Facebook (https://www.facebook.com/EngineeringJrnl).

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Journal

Engineering

DOI

10.1016/j.eng.2024.11.027 

Article Title

Excellent Insulation Vacuum Glazing for Low-Carbon Buildings: Fabrication, Modeling, and Evaluation

 

New research indicates effects of PTSD on body vary by culture

ASU scientists first to examine hormones and PTSD in non-industrialized society

Arizona State University

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Turkana research assistant Amuria Lotiira holds a saliva collection tube and explains the protocol to potential participants in an ASU study. In 2015, a team tested levels of cortisol and testosterone from saliva samples from Turkana pastoralist warriors in Kenya. A Turkana-area chief sits to the left of Lotiira. Photo by Matthew Zefferman

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Credit: Photo by Matthew Zefferman

According to the World Health Organization, about 3.9% of the world's population has had post-traumatic stress disorder at some point during their lives. That number is higher in the United States, at about 6%.

PTSD can happen to an individual after experiencing or witnessing a traumatic event and can last for months or years. But there is a lot that is still not understood about this mental health condition.

Anthropologists, social scientists and veterans from Arizona State University and the Naval Postgraduate School are the first to analyze the relationship between the hormones cortisol and testosterone and PTSD in a non-industrialized society.

This new study sheds more light on the PTSD puzzle.

Homing in on hormones

Previous studies about PTSD and hormones have focused only on people living in Western or European industrialized societies. They included people who suffered from different types of trauma like car crashes, assault and multiple deployments, according to Ben Trumble, a research scientist at the Institute of Human Origins and associate professor at the School of Human Evolution and Social Change.

The studies showed the majority of people diagnosed with PTSD had very little change in their cortisol levels throughout the day. Instead, the results showed “blunted” levels of cortisol and not the normal rise and fall patterns. 

“In healthy men, hormones like testosterone and cortisol follow a pattern throughout the day,” Trumble said. “Hormone levels are the highest just after waking up, and then decline rapidly. Levels are low throughout the day, and rise again at night.”

The big question Trumble and colleagues wanted to answer was, would they see this same pattern in a non-industrialized population with people who suffered from the same type of trauma?

“Our study is the first to examine associations between hormones (cortisol and testosterone) among the Turkana,” Trumble said. “Turkana pastoralists experience a high degree of combat exposure, and 28% of men have symptoms of PTSD. Because nearly everyone gets exposed to combat, we can see if there are biological differences in hormones for those with PTSD and those without PTSD. So, in this case we can compare apples to apples and not apples to oranges.”

What the ASU scientists found was surprising.

“We did not find any difference in cortisol for Turkana warriors with a provisional PTSD diagnosis versus those without PTSD,” said Michael Baumgarten, an Institute of Human Origins-affiliated graduate student and Army Ranger veteran. “Both groups of warriors had nearly identical cortisol patterns. Interestingly, Turkana men with PTSD had lower testosterone when they woke up compared to those without PTSD.”

“A more applied takeaway is to look at the results of this study and either retain or increase the level of skepticism one has of narratives that claim to have a crystal-clear picture of how human physiology responds to the stresses of combat — especially if they are trying to sell you something,” he said.

Why the Turkana?

Being a livestock farmer, or pastoralist, in Kenya near South Sudan can be dangerous and deadly. 

The Turkana are mobile pastoralists and engage in cattle raiding, said Matthew Zefferman, an assistant professor at the Naval Postgraduate School and U.S. Air Force veteran.

Zefferman spent half a year in the field with the Turkana during his postdoctoral fellowship at ASU.

“The Turkana in our study area, who raid other pastoralists, typically do so across the disputed border with South Sudan,” he said. “They travel by foot, often over 60 miles and engage in small and large raids. They are also raided by members of other pastoral groups. These raids can result in firefights and the death of family members, and the loss of animals. About half of adult male deaths in the study area is due to raiding."

Turkana warriors experience similar trauma from combat exposure during cattle raids. They also share similar cultural backgrounds and are the same gender. This differs from previous studies conducted where trauma and cultural background are different.

"It is interesting to see how the physiological response to trauma exposure can differ based on cultural environment,” said Sarah Mathew, a research scientist at the Institute of Human Origins and associate professor at the School of Human Evolution and Social Change. “It suggests that we can't answer basic questions about human biology by only studying industrialized populations."

Mathew’s relationship with the Turkana since 2007 led to this project and many others, providing valuable information about non-industrialized cooperation, cultural norms and warfare. 

While the study answers questions about hormonal regulation, there is still the question of why are the Turkana cortisol levels “normal” in those diagnosed with PTSD compared with Western populations? 

The study sites many possible reasons including physical activity and cultural differences. The scientists say more research is needed.

A previous publication by Zefferman and Mathew stated that unlike soldiers of nation-state societies, "Turkana warriors are strongly endorsed by the whole community, have elevated status, perform culturally sanctioned rituals after raids, and are deeply integrated with their corresponding civilian community.

“These longstanding cultural traditions of warriorhood may buffer them from some of the negative physiological responses to combat trauma.”

Mathew and the others emphasize the importance of sharing their findings with the Turkana. The researchers have engaged with the community over several years, and discuss findings from this and other ongoing studies and what these findings mean for future research.

“We can only do this research because of the support and help of the people we do the research with — the Turkana,” Zefferman said. “We acknowledge that their willingness to work with us is what has allowed us to do this research with potential benefits to our society.

“We go there at the grace of the people we work with.”

The article, “Little evidence that posttraumatic stress is associated with diurnal hormone dysregulation in Turkana pastoralists,” was published in the journal Evolution, Medicine, & Public Health. 

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DOI

10.1093/emph/eoaf004 

Method of Research

Data/statistical analysis

Subject of Research

People

Article Title

Little evidence that posttraumatic stress is associated with diurnal hormone dysregulation in Turkana pastoralists

Racial and ethnic differences in out-of-pocket spending for maternity care

JAMA Health Forum

About The Study: In this study, differences in out-of-pocket maternity spending among the commercially insured were associated with differences in coinsurance rates. These costs could lead people to forgo needed health care or other basic needs that support health (e.g., food or housing). Changes to health plan benefit design could improve equity in out-of-pocket maternity spending and its consequences.

Corresponding Author: To contact the corresponding author, Anna D. Sinaiko, PhD, MPP, email asinaiko@hsph.harvard.edu.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/

(doi:10.1001/jamahealthforum.2024.5565)

Editor’s Note: Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial disclosures, and funding and support.

#  #  #

Embed this link to provide your readers free access to the full-text article This link will be live at the embargo time https://jamanetwork.com/journals/jama-health-forum/fullarticle/10.1001/jamahealthforum.2024.5565?utm_source=For_The_Media&utm_medium=referral&utm_campaign=ftm_links&utm_term=022825

About JAMA Health Forum: JAMA Health Forum is an international, peer-reviewed, online, open access journal that addresses health policy and strategies affecting medicine, health and health care. The journal publishes original research, evidence-based reports and opinion about national and global health policy; innovative approaches to health care delivery; and health care economics, access, quality, safety, equity and reform. Its distribution will be solely digital and all content will be freely available for anyone to read.

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Journal

JAMA Health Forum

 

Changes in food insecurity among US adults with low income during the COVID-19 pandemic

JAMA Network Open

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About The Study: 

During the COVID-19 pandemic, food insecurity decreased among Supplemental Nutrition Assistance Program (SNAP) participants in most racial and ethnic groups but did not decrease among non-SNAP participants in any group. These results suggest that during the pandemic, increased SNAP benefit amounts were associated with ameliorating food insecurity for many U.S. adults who were able to access SNAP but did not reduce racial and ethnic disparities in food insecurity.

Corresponding Author: To contact the corresponding author, Yingfei Wu, MD, MPH, email yingfeiwu322@gmail.com.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/

(doi:10.1001/jamanetworkopen.2024.62277)

Editor’s Note: Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial disclosures, and funding and support.

#  #  #

Embed this link to provide your readers free access to the full-text article This link will be live at the embargo time https://jamanetwork.com/journals/jamanetworkopen/fullarticle/10.1001/jamanetworkopen.2024.62277?guestAccessKey=c0957767-f5eb-4d6d-88a4-15c747418b57&utm_source=for_the_media&utm_medium=referral&utm_campaign=ftm_links&utm_content=tfl&utm_term=022825

About JAMA Network Open: JAMA Network Open is an online-only open access general medical journal from the JAMA Network. On weekdays, the journal publishes peer-reviewed clinical research and commentary in more than 40 medical and health subject areas. Every article is free online from the day of publication. 

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Journal

JAMA Network Open

 

Study reveals racial and ethnic disparities in maternity care spending

University of Maryland

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Dr. Rebecca Gourevitch is Assistant Professor in the Department of Health Policy and Management at UMD's School of Public Health. 

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Credit: UMD

COLLEGE PARK, MD – A new study out today in JAMA Health Forum is the first to show that Black, Hispanic and Asian people with private insurance tend to pay more out-of-pocket for maternity care than white people. 

“The average additional spending on medical care from pregnancy through postpartum paid by people who are Black, Hispanic and Asian is significantly more than white people,” said Dr. Rebecca Gourevitch, the study’s lead author and an assistant professor in the Department of Health Policy and Management at the University of Maryland School of Public Health (UMD SPH). 

“We found that out-of-pocket costs were highest for Black people overall through pregnancy, delivery and postpartum. The study shows yet another way that people from different racial and ethnic groups are having different experiences of maternity care. And the burden of greater out-of-pocket costs could have a real impact on maternal health.” 

Differences were most pronounced during pregnancy: For recommended prenatal care services, Black people paid on average 74% more, Hispanic people 51% and Asian people 4% more than white people, the study found. At delivery and postpartum, disparities were smaller. Overall, Black and Hispanic people’s out-of-pocket costs on maternity care were a significantly higher proportion of their household income. 

Led by researchers at UMD SPH and the Harvard T.H. Chan School of Public Health, the study measured out-of-pocket spending in over 87,000 pregnancies, deliveries and the first 42-days postpartum. Researchers reviewed anonymized data from Blue Cross Blue Shield of Massachusetts (BCBSMA) over five years (2018-2022). The researchers measured out-of-pocket spending in dollars and as a percentage of median household income in the member’s area. Over a quarter (26.9%) of pregnancies were in areas with a median household income of $75,000 or less. 

“Blue Cross has long prioritized closing inequities in health care and helping improve care for everyone. We undertook this study to understand one potential contributor to longstanding inequities in maternal health outcomes as a basis for designing solutions that make care more equitable,” said Dr. Mark Friedberg, senior vice president of performance measurement & improvement at Blue Cross and study coauthor. 

Gourevitch says that spending disparities are in large part driven by coinsurance rates. Coinsurance is the percentage of the cost of a medical service that the patient must pay, after they have paid their plan’s annual deductible amount. Black or Hispanic people are more likely to be enrolled in insurance plans that have high coinsurance levels, above 10%. 

“Coinsurance often only applies to care provided in the hospital. But for high-cost services like a delivery, paying 10% or more of the cost of the hospitalization can be a lot,” said Anna Sinaiko, study senior author and associate professor of health economics and policy at Harvard’s TH Chan School of Public Health. 

Some states, including Massachusetts, are considering legislation to eliminate out-of-pocket costs for maternity care, according to the Boston Globe. Based on their findings, Gourevitch and Sinaiko say this kind of policy change would have the largest impact on Black and Hispanic people, who face the highest costs. 

“Our results reveal that health insurance companies, employers and policymakers have an opportunity to lower out-of-pocket costs for all pregnant and postpartum people and to reduce disparities in costs by changing how health insurance plans are designed,” said Gourevitch.   

To request an interview with Dr. Gourevitch, please contact sph-comm@umd.edu. 

Funding for this project was provided by The Donaghue Foundation. The Donaghue Foundation had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication. Data was provided by Blue Cross Blue Shield Massachusetts, the Centers for Disease Control and Prevention WONDER (Wide-ranging Online Data for Epidemiologic Research) databases and the U.S. Census American Community Survey.

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Journal

JAMA Health Forum

DOI

10.1001/jamahealthforum.2024.5565 

Method of Research

Data/statistical analysis

Subject of Research

People

Article Title

Racial and Ethnic Differences in Out-of-Pocket Spending for Maternity Care

Article Publication Date

28-Feb-2025