This protocol is based on home health care (HHC) best practice evidence showing the value of coupling timely post-acute care visits by registered nurses and early outpatient provider follow-up for sepsis survivors. We found that 30-day rehospitalization rates were 7 percentage points lower (a 41% relative reduction) when sepsis survivors received a HHC nursing visit within 2 days of hospital discharge, at least 1 more nursing visit the first week, and an outpatient provider follow-up visit within 7 days compared to those without timely follow-up. However, nationwide, only 28% of sepsis survivors who transitioned to HHC received this timely visit protocol. The opportunity exists for many more sepsis survivors to benefit from timely home care and outpatient services. This protocol aims to achieve this goal. Guided by the Consolidated Framework for Implementation Research, this Type 1 hybrid pragmatic study will test the effectiveness of the Improving Transitions and Outcomes of Sepsis Survivors (I-TRANSFER) intervention compared to usual care on 30-day rehospitalization and emergency department use among sepsis survivors receiving HHC. The study design includes a baseline period with no intervention, a six-month start-up period followed by a one-year intervention period in partnership with five dyads of acute and HHC sites. In addition to the usual care/control periods from the dyad sites, additional survivors from national data will serve as control observations for comparison, weighted to produce covariate balance. The hypotheses will be tested using generalized mixed models with covariates guided by the Andersen Behavioral Model of Health Services. We will produce insights and generalizable knowledge regarding the context, processes, strategies, and determinants of I-TRANSFER implementation.As the largest HHC study of its kind and the first to transform this novel evidence through implementation science, this study has the potential to produce new knowledge about the impact of timely attention in HHC to alleviate symptoms and support sepsis survivor’s recovery at home. If effective, the impact of this intervention could be widespread, improving the quality of life and health outcomes for a growing, vulnerable population of sepsis survivors. A national advisory group will assist with widespread results dissemination. Sepsis is a life-threatening acute organ dysfunction secondary to infection . Acute cAnnually, up to one-third of sepsis survivors transition from acute care to skilled home health care (HHC) where nurses monitor for reinfection, support uninterrupted medication management, manage symptoms, and work with patients, caregivers, and other providers to support continued recovery , 24. VigIt is during the first few weeks of HHC that sepsis survivors are most at risk for rehospitalization , indicatThe first homecare visit, usually conducted by a registered nurse, is one of the most critical steps of the home care episode , 36, andPhysicians must certify the eligibility of patients for HHC, and review and sign the orders for care . CurrentOur prior evidence indicates that neither early HHC nursing nor outpatient provider visits alone significantly reduced hospital readmissions in two high-risk populations (heart failure and sepsis). In contrast, when the two practices were combined, early hospital readmissions were significantly reduced. In our prior comparative effectiveness study using national Medicare data and an instrumental variable analysis approach, we found 30-day rehospitalization rates were 7 percentage points lower (41% relative reduction) for sepsis patients when a HHC nursing visit was received within 2 days of hospital discharge, at least 1 more nursing visit the first week, and an outpatient provider follow-up visit by 7 days occurred compared to those without timely follow-up , 24.The literature suggests a critical need to implement best practices to increase awareness of sepsis survivors and to improve the delivery of timely care during transitions , 39–43. Our I-TRANSFER intervention is designed to address several barriers and gaps that may jeopardize the implementation of early post-acute surveillance. Sepsis survivors are not consistently identified with a medical diagnosis of sepsis until after discharge from acute care –55. ThisAim 1 of our study is to test the effectiveness of the I-TRANSFER intervention compared to usual care on 30-day rehospitalization and emergency department (ED) use among sepsis survivors receiving HHC. We hypothesize that compared to usual care, sepsis survivors who receive the I-TRANSFER intervention will have significantly fewer all-cause 30-day rehospitalizations, inpatient days if rehospitalized, and ED visits within 30 days of hospital discharge.Aim 2 of our study is to produce insights and generalizable knowledge regarding the context, processes, strategies, and determinants of I-TRANSFER implementation. We will assess readiness of the sites using the Organizational Readiness for Implementing Change (ORIC) survey. The ORIC survey includes 12 questions related to the participant’s perception of their organization’s readiness to implement the intervention including characteristics like confidence, motivation, support, flexibility, addressing challenges, and coordination . We willAs illustrated in Fig. There are three types of Individual Determinants in the Andersen framework. Predisposing factors include age, sex as a biological variable, race, and informal support, for example. Enabling factors include facilitators of the use of health care services . Need/illness level includes health status such as acute and chronic disease, cognitive and physical functioning, symptoms such as pain and anxiety, and recent prior hospitalizations. Determinants in the Andersen framework will also be considered for risk adjustment and when forming our national, covariate-balanced control sample (Aim 2). Conceptually, the outcomes are jointly determined by the determinants in the Andersen framework as well as the home health and physician services provided during the HHC episode. Because sicker patients are more likely to use more HHC and physician services and are likely to have worse outcomes – that is, the receipt of increasing levels of HHC and physician services is endogenous – a simple comparison of outcomes will yield misleading biased results and are taken into consideration in the analytic plan.The Consolidated Framework for Implementation Research (CFIR) guides Aim 2 and contains 5 constructs to assess context and implementation determinants at each site. Context has been defined as the set of circumstances or unique factors that surround a particular implementation effort  and anytThe study was designed based on evidence from our previous study; extensive preliminary work with national data, hospital, and HHC stakeholders; & implementation science literature , 64–72. Sepsis survivors transitioned to the participating HHC agencies during the period before implementation serve as the usual care control group compared to those exposed to I-TRANSFER, the intervention group. To address historical threats and to increase generalizability, we form control comparison groups from national Medicare clinical and administrative claims data within and outside our partner sites to compare to our intervention group: 1) one year prior to any contact with our team; 2) during the onboarding period, and 3) across the entire study period. Observations on survivors from outside our partners’ sites will be weighted using entropy balancing –76 to prEach hospital and HHC agency dyad will assemble a site implementation team comprised of key stakeholders and project champions involved in the planning and implementation. The principal investigator and at least two other research team members will visit each site in person and stay in close phone or email contact with the site coordinator and team for onboarding and Aim 2 data collection. Additional contacts may occur if needed. We have planned 12 in-person visits and frequent, standardized phone, virtual and/or email contacts. Expected site stakeholders may include, for example, a programmer to write a query to identify the inpatient sepsis survivors; hospitalists, emergency room physicians, sepsis experts, and ambulatory providers to determine follow-up appointment workflow, and hospital case managers are expected to be important informants overall. On the HHC side, the teams will include a hospital based HHC liaison who facilitates the referrals and transfer of patient information to the HHC agency; an HHC intake nurse who schedules the first visit and assigns the visiting nurses; a HHC nurse who knows the workflow for planning visits and working with patients; an intake director who understands the entire workflow; the Directors of Nursing or Chief Operating Officers who oversee operations. These stakeholders will participate in individual, or group interviews and survey completion as described below. An estimated 60 stakeholders will provide informed consent prior to data collection. A study site coordinator identified by each dyad will assist with communication, scheduling, oversight, and data collection at each site. A project manager will track progress and support the work across all sites. Stakeholder consent to participate will be obtained prior to each interview by the study team member conducting the interview.Implementation of the I-TRANSFER components will be guided by the stakeholders and research team using intervention mapping, as described below. The context and determinants , processes, and strategies encountered during Aim 1 will be collected for Aim 2 analysis. Hospital partners will work with the study and HHC team to achieve the following components of I-TRANSFER: identify the sepsis survivors during the hospitalization, make the outpatient follow-up appointment before discharge, notify the HHC agency of a sepsis survivor, conduct timely home health visits and outpatient visits in week one. Based on our preliminary work, we have identified several effective strategies that we can suggest to better identify the sepsis survivor, including generalizable use of sepsis order sets within the electronic health record . We willChallenges we expect to face in making and achieving a timely outpatient visit are limited appointment availability, and patients who cancel or do not attend the visit. A potential strategy is to increase awareness about I-TRANSFER’s evidence and include a script for the clinician to educate the patient about the value and importance of the outpatient visit. Transportation may be an issue as well and will be brainstormed for solutions with the stakeholders and tracked as a barrier. Hospital based personnel will notify the HHC intake department when the patient is a sepsis survivor. The intervention mapping will determine the workflow for this component with each site. It may include phone calls, text messaging, faxed or electronic documents.HHC intake personnel will likely schedule the nurse visits and notify the visiting nurse of the sepsis diagnosis and date of the outpatient appointment. To meet protocol, the first registered nurse home visit will occur within 2 days of hospital discharge, with a second visit that week. The patient will be encouraged and assisted if necessary (e.g. transportation) to attend their scheduled outpatient appointment.A four-member interdisciplinary, national advisory board with expertise in sepsis and HHC will advise the team via teleconference once in year one and twice in years 2–5. They will review the CFIR interview guide, and findings from the onboarding and implementation phases, providing advice as the study progresses. The national advisory board brings expertise in sepsis and HHC and will have a major role in facilitating dissemination of the study findings through access to national stakeholder groups.Onboarding is a 6-month period when the implementation and research teams plan the implementation. Intervention is the 12-month period when I-TRANSFER is in operation. Maintenance is a 6-month period when the research team assesses whether the intervention continues without research team monitoring and feedback. The analysis will be an intent to treat. We will adjust for time, or any health system interventions, as well as patient covariates that may confound the findings using generalized mixed models.Sample sizes needed to provide sufficient power were calculated using Stata . PrelimiThe I-TRANSFER intervention is targeted at the hospital and HHC agency and is considered part of clinical care implemented for all sepsis survivors. There is no individual patient recruitment, prospective assignment, or primary data collection from patients. The analysis will be completed on existing datasets. We will analyze a sample drawn from all Medicare fee-for-service sepsis survivors discharged to HHC during a 4-year period (01/01/2021 and 12/31/2024). Analyses from our 2013–14 dataset suggests that without exclusions there will be approximately 800,000 sepsis discharges per year who receive HHC [Ten clinical sites located in the United States have committed to participate as dyads, 5 referring hospitals and their 5 partnered home health agencies. Sites were selected based on our relationships with staff, ownership status , commitment to appoint an implementation team, size, geography, and diversity (academic and community). We sought regional diversity with sites in the East and West. To be eligible HHC agencies must be Medicare certified to generate claims and confirm a hospital referral source as a partner.We expect approximately 60 stakeholders to comprise the Aim 2 sample. Acute care and HHC site champions including hospitalists, emergency room physicians, programmers, managers, sepsis experts, ambulatory providers, care coordinators, Directors of Nursing, home health liaisons, intake personnel and nurses, are the expected subjects. After informed consent, they will be administered the ORIC survey and interviewed by the study team using the CFIR interview guide.The primary outcome of Aim 1 is 30-day all-cause hospital readmissions. Secondary outcomes are number of inpatient days , and ED use within 30 days, all measured through the Medicare Administrative Data.The outcomes of Aim 2 will be the alternative approaches in workflow, barriers, facilitators, and differences in acceptability observed between the study sites during implementation of the I-TRANSFER protocol. These alternative approaches will be noted, compared, contrasted, and reported as study results so agencies with similar barriers can see suggested solutions to increase generalizability of the findings.A national sample of Medicare administrative, home health OASIS and claims data from CMS Chronic Condition Warehouse (CCW) will be employed Table . This wiSource files will also include: (1) the CMS Provider of Services file containing information on hospital, home health, and other provider characteristics such as ownership and length of participation in the Medicare and Medicaid programs; (2) the Area Health Resources file which is a national, county-level record of the supply of health care services maintained by the US Health Resources and Services Administration; and (3) Census data that include ZIP-code level socio-economic measures for the patients’ place of residence.The OASIS is a comprehensive assessment tool designed to collect nearly 100 items related to a home health recipient’s functional status, clinical status, and service needs at several time points during a HHC episode. Mandated by CMS since 1999, the OASIS is the most comprehensive national data set on HHC patients. OASIS data are collected upon admission, every 60 days, if transferred to an inpatient facility, and at discharge. The OASIS will be the source of detailed patient clinical data including, importantly, functional status, health therapies, the result of a drug regimen review and whether patient-specific parameters have been established for notifying the physician of changes in vital signs or other clinical findings. The reliability of OASIS functional items varies. Mobility and transferring have Kappa values > 0.70, while lower body dressing and bathing have Kappa values of 0.61 and 0.53, respectively. All other items to be analyzed in the proposed study have at least moderate reliability (Kappa ≥ 0.40) with the exception of eating and meal preparation (Kappa = 0.38 for both) which primarily will be used to control for differences in functioning on HHC admission .Data for Aim 2 will be generated through three sources: by administering the Organizational Readiness for Implementing Change (ORIC) survey, a needs assessment at each site, and the Consolidated Framework for Implementation Research (CFIR) interviews.At baseline, each acute care and home health stakeholder will complete the ORIC 12-item survey to assess readiness for change that refers to organizational members' shared beliefs in their collective capability to change  and their shared resolve to implement a change . Based on a 5-point Likert scale of agree to disagree, the tool has high inter-item consistency, inter-rater reliability, inter-rater agreement, good model fit and item loadings. The ORIC score is calculated by summing across all items. Lower scores represent less organizational readiness for implementing change; higher scores represent a more favorable readiness for implementing change .Implementation Mapping. The systematic process of implementation mapping has 5 steps for developing strategies to improve adoption, implementation, and maintenance of evidence-based interventions in the real world . These swww.CFIRguide.org. Examples include: Relative advantage: How does the intervention compare to other similar existing programs in your setting? Peer pressure: To what extent would implementing the intervention provide an advantage for your organization compared to other organizations in the area? Leadership engagement: What kind of support or actions can you expect from leaders in your organization to help make implementation successful? Patient needs and resources: How do you think individuals served by your organization will respond to the intervention? How well will the intervention meet their needs?A CFIR derived interview guide that measure context, process, and implementation determinants was generated by the team using the online resources at The team will train together in administering the CFIR interviews. CFIR interviews may be individual or in groups; implementation mapping (described above) will be done in groups as appropriate to gain consensus and promote team engagement in planning. For example, mapping the workflow for notifying the HHC intake department may be completed with the group of nurses who staff the HHC intake department. All interviews will be recorded. We will catalogue the implementation strategies and workflows suggested, adopted, modified, or discarded by the participating dyads. Data will be entered and stored in Research Electronic Data Capture (REDCap) , 86 or NA key initial task is the identification of all sepsis survivors in the national hospital dataset. Consistent with our prior work, we will use two complementary strategies to identify sepsis survivors. First, we will use the explicit International Classification of Diseases 10th Revision (ICD-10) codes . Second, we will employ the implicit approach used in our previous study and developed by Angus and colleagues  that reqEach hospital discharge of a sepsis survivor to HHC will represent a separate record on the timeline file. Some Medicare beneficiaries will have more than one index hospital discharge during the study period. Data available will give us the flexibility to define an “index” hospitalization in several ways. Our main approach will be to analyze all eligible hospitalizations followed by HHC and to adjust for the potential effect of clustering at the patient and provider level. We plan to examine the sensitivity of our results to alternative specifications of the “index” hospital stay including analyses based on a single index hospitalization per person.Deidentified Medicare claims will be the source of information used to construct Aim 1 outcomes of rehospitalization, total hospital days if readmitted and ED utilization. The CMS claims will be stored a secure, password protected site. The CMS approach to identifying hospital readmissions was successfully used in our heart failure and sepsis studies and we will use the same approach to identify readmissions in this study , 50. ObsIn addition to the survivors from the treated dyads in the baseline period, additional control survivors will be used to provide a much larger sample of control observations. These observations will be drawn from the population of Medicare sepsis survivors not being cared for by any of the participating institutions. This sample is unlikely to be balanced on covariates, a priori, with the sample of survivors from participating providers. Therefore, entropy balancing will be used to create sampling weights for these observations to produce balance on covariates. All hierarchical regression analyses will take these entropy balance weights into account. In addition to an intent-to-treat indicator, the regression will include covariates specified by the Andersen Behavioral Model. Inpatient days after the index discharge will be modeled using hierarchical Poisson regression. ED utilization will be modeled using hierarchical logistic regression.The pragmatic aspects of the study design make it important to conduct various sensitivity and exploratory analyses. Sensitivity analyses will include checks of robustness of findings with and without sepsis survivors who are readmitted shortly after discharge , those with a resumption of HHC episode, discharges with very short (1 day) or very long hospital stays (30 days or more), and survivors less than 65 years old. Exploratory analyses will include estimation stratified by type of sepsis, sex , and hospital ownership status.The recorded needs assessments and CFIR interviews will be transcribed by a secure, professional service. All study materials will be stored in a secure, password protected site. The typed interview transcripts and observation notes will be uploaded into qualitative software NVivo 11.0  to facilStrategies to increase and ensure the trustworthiness and scientific adequacy of the study include credibility (iteratively member checking the findings with the site implementation teams); and transferability  . CredibiAn indicator on the OASIS diagnosis list documenting the identification of sepsis survivors at the beginning of HHC will be modeled using hierarchical logistic regression. We will use Medicare claims dates and site of service to identify the timing of HHC nursing visits and community provider visits. This indicator for whether the protocol for timely nursing and community provider visits was achieved will be modeled using hierarchical logistic regression. At the 12-month point from the go-live start of implementation, the study team will stop communicating and monitoring fidelity with the stakeholders. Outcomes of sepsis diagnoses and visit patterns will be compared during the “maintenance” period evaluating for stability or decline in the proportion of sepsis survivors identified and/or receiving the early visits compared to the intervention period. Hierarchical regressions will be extended through the maintenance period and separate treatment indicators for the intervention period and the maintenance period. Regressions will test equality of coefficients on the treatment indicators on the two periods. Equality of coefficients will imply maintenance of effects after the study team exits. A data monitoring committee is unnecessary as this is a low-risk, implementation science study with voluntary partners.Sepsis takes more lives than opioid overdoses, breast cancer, and prostate cancer combined . Prior sOur study, however, is not without limitations. It is possible that dyads may begin to implement parts of the protocol prior to the implementation period. However, we believe the specifications of the I-TRANSFER components will be difficult to achieve in full and effectively without collaborative efforts. To be safe, additional specification checks will include treatment indicators in the retrospective control data and onboarding period to determine whether such activities were taking place. We will also ask the status and quality of such interventions prior to onboarding and would recruit a new dyad if it is an issue.Also, the sample of sepsis survivors from non-participating dyads is a useful comparison group only if the distributions of characteristics of those survivors and their care providers overlap/match with those of survivors from the participating dyads. By using the entire Medicare population, the risk of lack of overlap is minimized. Nevertheless, should lack of overlap be an issue, we will use matching techniques to mitigate this threat. Lastly, we considered a cost analysis but due to budgetary constraints could not include a robust analysis. Instead, we will document whether there are added costs to the dyads such as adding a position, and we will have the data from the claims to roughly compare differences in service utilization such as numbers of HHC visits, outpatient care, or observation stays.As the largest HHC study of its kind and the first to transform this type of care through implementation science, this study has the potential to produce new knowledge about the process of transition to and care in home health. If effective, the impact of this intervention during this common transition process could be widespread, improving the outcomes for a growing, vulnerable population of sepsis survivors.


Recently, hemp-fiber-reinforced polymer (HFRP) composites have been developed to enhance the strength and ductility of normal and lightweight aggregate concrete along with recycled brick aggregate concrete. In addition, both experimental and analytical investigations have been performed to assess the suitability of the existing strength and strain models. However, the theoretical and analytical expressions to predict the stress–strain curves of HFRP-confined concrete were not developed. Therefore, the main objective of this study was to develop analytical expressions to predict the stress–strain curves of HFRP-confined waste brick aggregate concrete. For this purpose, a new experimental framework was conducted to examine the effectiveness of HFRP in improving the mechanical properties of concrete constructed with recycled brick aggregates. Depending on the strength of the concrete, two groups were formed, i.e., Type-1 concrete and Type-2 concrete. A total of sixteen samples were tested. The ultimate compressive strength and strain significantly increased due to HFRP confinement. Improvements of up to 272% and 457% in the ultimate compressive strength and strain were observed due to hemp confinement, respectively. To predict the ultimate compressive strength and strain of HFRP-confined concrete, this study investigated several existing analytical stress–strain models. Some of the strength models resulted in close agreement with experimental results, but none of the models could accurately predict the ultimate confined strain. Nonlinear regression analysis was conducted to propose expressions to predict the ultimate compressive strength and strain of HFRP-confined concrete. The proposed expressions resulted in good agreement with experimental results. An analytical procedure was proposed to predict the stress–strain curves of hemp-confined concrete constructed by partial replacement of natural coarse aggregates by recycled fired-clay brick aggregates. A close agreement was found between the experimental and analytically predicted stress–strain curves. A significant number of nonrenewable resources have been used in the manufacturing of concrete and mortar, which involves adverse environmental effects. Some nonrenewable resources such as sand, gravel, and cement combine to form concrete. Approximately 60% of raw materials from the lithosphere are used in construction globally. Additionally, extensive construction activities have resulted in the depletion of natural resources . ImportiEnvironmental protection, the prevention of nonrenewable resources, and energy conservation all work together in environment-friendly development processes ,3,4. IssAccording to Yang et al. , a 20% aConcrete made using recycled brick aggregates has inferior characteristics to natural aggregate concrete ,20,21,222 during production. The impact of jute, sisal, and hemp fibers on the strain and the ultimate compressive strength of concrete was examined by Hussain et al. [Cotton, jute, flax, sisal, and hemp are some eco-friendly natural fibers made from textile and agricultural production that have been effectively employed for concrete repair and reinforcement ,36. Thesn et al. . It was n et al. , it was n et al.  to wrap The goal of this research work is to enhance the subpar mechanical characteristics of recycled aggregate concrete (RAC) that contains a 50% replacement of natural aggregates with fired-clay brick aggregates (CBB). Recently, a study was conducted to partially replace natural aggregates with hydraulically pressed cement brick aggregates . HoweverA total of sixteen concrete cylinders were tested in two groups. The diameter and height of each cylinder were 150 mm and 300 mm, respectively. Each group comprised eight cylinders, and the cylinders in two groups were differentiated based on their concrete strength. In each group, two cylinders were tested without strengthening and served as control specimens. Hemp fiber rope layers were applied to the remaining six cylinders. One, two, and three layers of hemp fiber ropes were applied to assess the effect of the quantity of strengthening material on mechanical properties. In the present work, the average results of two cylinders from the control, one-layer strengthening, two-layer strengthening, and three-layer strengthening are reported. The attributes of the test matrix are illustrated in Type-I Portland cement was utilized for the construction of all cylinders. The selected slump values for Type-1 and Type-2 concrete were 90 mm and 70 mm, respectively. Fired-clay interlocking bricks made of clay were used to partially replace 50% of coarse natural aggregates. Natural aggregates are shown in 3), compressive strength at 6.26 (MPa), and water absorption at 12.30%. At the same time, the density of natural aggregates was approximately 2400–2600 kg/m3. ASTM standards were followed to estimate the mechanical properties of bricks, including their density, water absorption, and compressive strength ,42. The The hemp ropes were bonded to the cylinders by using a two-part polyester resin. The locally available polyester resin was used in this study. The polyester resin was obtained from RUGSVANICH (1992) company limited, Bangkok, Thailand. The mixing ratio of resin and hardener was 2:1. The produced epoxy was used to bond hemp ropes and concrete by using a hand brush. The strengthening of cylinders was performed after the curing period of 28 days. Hussain et al.  recognizTo record the axial deformations, two linear variable displacement transducers (LVDTs) were fixed around cylinders. Each sample was subjected to a monotonic compressive load by utilizing a Universal Testing Machine with a 2 MN capacity. A loading rate of 4000 N/s was applied throughout the testing. To prevent any unintentional weight transfer to the fiber ropes at significant axial deformations, steel plates were mounted to the top and bottom sides of cylinders. A calibrated load cell was positioned at the top of the cylinders to measure the intensity of the load applied to it. The testing setup can be seen in The experimental results in terms of compressive strength and strain and their improvements due to hemp fiber ropes are presented in The compressive stress–strain curves of the control and hemp-confined specimens of the Type-1 and Type-2 strength concrete groups are shown in The comparison of the increase in ultimate compressive strength and the corresponding strain of Type-1 and Type-2 concrete specimens confined by hemp ropes is shown in t describes the thickness of FRP sheets, and D defines the concrete core diameter.Several researchers have proposed analytical models to predict the stress vs. strain behavior of concrete confined by Fiber-Reinforced Polymer (FRP) sheets. Some of the existing models are summarized in The results of theoretical compressive stress models are compared to the experimental results in It is evident from the above discussion that existing stress–strain models developed for FRP confinement cannot predict the ultimate strength and strain of HFRP-confined concrete. Therefore, analytical models specifically developed for hemp confinement must be proposed. The following section presents a regression-based approach to predict the compressive stress–strain curves of HFRP-confined concrete.It is discussed in Existing confinement models were also unable to accurately predict the ultimate compressive strain of HFRP-confined concrete. Therefore, Equation (5) was proposed for the ultimate compressive strain of HFRP-confined concrete. The A two-stage relationship between the compressive stress and strain of HFRP-confined concrete is proposed in the present study, as shown in concrete .Scott et al.  describeTo define the ascending branch of HFRP-confined concrete, the values of The stress vs. strain response in Region 2 is assumed to be linear with a slope Once parameters The approach proposed in Specimens confined with hemp ropes exhibited a bilinear stress–strain response. Contrary to control specimens, the axial ductility was significantly improved as a result of the hemp fiber rope confinement. The peak axial strength and the corresponding strain in Type-1, as well as Type-2 concrete, increased with the increase in the number of hemp rope layers. Furthermore, the maximum compressive strength and strain were observed in the case of the 3-layer confinement. The improvement in the ultimate compressive strength and strain was more pronounced as the compressive strength of unstrengthened concrete decreased. Improvements of up to 272% and 457% in the ultimate compressive strength and strain were observed due to hemp confinement.The ultimate compressive strength and strain were predicted in this research work using existing analytical stress–strain models. Several models were shown to reasonably predict the compressive strengths. However, none of the models could accurately predict peak strain. Therefore, it was found necessary to propose expressions for predicting the characteristic points on the compressive stress–strain envelope of HFRP-confined RAC.Nonlinear regression analysis was conducted to propose expressions to predict the ultimate compressive strength and strain of HFRP-confined concrete constructed by partial replacement of natural coarse aggregates by recycled fired-clay brick aggregates. In addition, expressions for the compressive stress and strain at the end of the initial stiff branch were also proposed. The proposed expressions resulted in good agreement with the experimental results.An analytical procedure was proposed to predict the stress–strain curves of HFRP-confined concrete constructed by partial replacement of natural coarse aggregates by recycled fired-clay brick aggregates. The compressive stress–strain curves of HFRP-confined RAC were idealized into two branches, i.e., a parabolic branch followed by a linear branch. The proposed regression expressions were utilized to trace the full compressive stress–strain curves of HFRP-confined RAC. A close agreement was found between the experimental and analytically predicted stress-strain curves.The results of this study could be used in multiple areas of civil and structural engineering, especially where there is a need to strengthen and or retrofit existing buildings. In addition, the developed models can be utilized for the design and analysis of reinforced concrete structures.The use of waste from fired-clay bricks aggregate to partially replace natural aggregates was the focus of this study. The mechanical characteristics of recycled aggregate concrete made of fired-clay brick aggregate are substandard. Hence, this research investigated the use of natural hemp fiber ropes to mitigate this substandard nature. The following important conclusions can be drawn from this research work:


After 48 h of abnormal operation, the temperatures of the inner surface of the heavy concrete of the wall, the inner steel plate of the wall, the outer surface of the heavy concrete of the wall, and the inner steel plate of the wall increased by 8.12, 8.11, 0.31, and 0.30 °C, respectively. The tensile strain of the heavy concrete of the wall increased significantly by 52.64%, and the compressive strain of the concrete increased by 67.33%, whereas the stresses of the studs and steel plates increased by only 1.57% and 6.79%, respectively. These results show that the change in the temperature field greatly influences the stress and strain on the TPC structure. As measures for mitigating the development of this unfavorable situation of temperature stress concentration, the temperature operating range should be rationally controlled or the junction structure between the transfer and purge sub-chambers of the TPC optimized accordingly. The results of our study can provide basic data for a dynamic analysis of the TPC under conditions of combined earthquake and temperature loads.A transfer–purge chamber (TPC) is a double-steel-plate, heavy-concrete, curved-surface composite structure composed of steel plates, heavy concrete, and shear connectors. It is an important facility in the external refueling system of a nuclear power plant (NPP), providing a safe and reliable biological shielding space for reactor refueling operations. Temperature load is one of the most important factors that must be considered in the design of NPP structures. The temperature loads experienced by the TPC during its life cycle include those encountered in both normal and abnormal operation, which are distinct. In this study, we investigated the steady state and transient-state temperature fields and stresses of a TPC structure under normal operation and after 48 h of abnormal operation, respectively, which were calculated using Abaqus finite element software and the directly coupled method. During normal operation, the temperature field of the structure shows relatively uniform changes, and the temperature gradient of the internal concrete in the direction of its thickness has a constant value of 0.245 °C/cm. At the junction between the transfer and purge sub-chambers of the TPC, under the influence of wall curvature and deformation constraints, the maximum tensile strain of heavy concrete is 8.84 × 10 Temperature load is an important non-negligible load to be considered in the structural design of nuclear power plant (NPP) buildings, which are usually large structures operating at high temperatures, based on its potential to induce large structural stress. In the event of an accident involving transiently high temperatures, temperature-load-induced stress is a control factor that can potentially determine the bearing capacity of the structure . The temAt present, research on the safety-related structures of NPPs mainly focuses on their ultimate bearing capacity. For example, the NUPEC (Nuclear Power Engineering Corporation) and the NRC (US Nuclear Regulatory Commission) jointly conducted more systematic and comprehensive research on the ultimate bearing capacity of a nuclear reactor containment under internal pressure ,5. On thCompared with the reinforced concrete structure used in traditional safety-related structures of an NPP, a steel-plate, heavy concrete structure is adopted for TPCs . This stIn thermodynamics, there are three modes of heat transfer: conduction, convection and radiation . Under nThe internal and external ambient environments of a TPC structure are uniform, have stable air, and have flat and smooth inner and outer surfaces. The temperature field of the TPC structure can be approximately considered as varying uniformly in the direction of the wall thickness, whereas thermal conduction can be considered a one-dimensional (1D) thermal conduction problem . For the1 and T2 are the air temperatures outside and inside the TPC structure, respectively; Tw1 and Tw2 are the temperatures on the outer and inner surfaces of the TPC wall, respectively; Q1 is the volume of conduction heat transfer from the outer surface of the TPC wall to the external air; Q2 is the volume of heat transfer from the inner surface to the outer surface of the TPC wall; and Q3 is the volume of heat transfer from the air inside the TPC to the inner surface of the TPC wall. A1 and A2 are the air-exposed areas of the outer and inner surfaces of the TPC. Since the diameter of the TPC structure is large and the diameter and height are much larger than the thickness of the wall, the calculations can be conducted according to the heat conduction problem of a large flat wall in heat transfer, that is, 1 and h2 are the convection heat transfer coefficients between the outer and inner surfaces of the TPC and air, respectively, and λ and δ are the equivalent thermal conductivity and thickness of the TPC wall and ceiling, respectively.Here, T1 and Tw2 on both sides of the wall; then, the heat flow . The heat flow Q31 is related to the temperature outside and inside the TPC structure.Combining Equations (1)–(3) results in the elimination of the temperatures TwWhen the temperature field is in a steady state,According to the Fourier thermal conduction equation, the temperature conduction in the TPC structure can be expressed as ,17(7)ρc1, Q2, and Q3 are nonequal terms.In this research, the heat conduction can be equivalent to a one-dimensional heat conduction problem along the thickness direction of the wall, and Formula (7) can be written as:In this paper, a finite element model is developed based on the transfer and purging chamber of a fourth-generation nuclear power plant in China. The transfer and purging chambers are mainly composed of a transfer chamber and a purging chamber. The transfer and purging chambers are located on the 20.20 m elevation floor of the NPP containment, with an elevation of 20.20−31.90 m. The inner and outer diameters of the transfer chamber are 4100 and 5100 mm, respectively, and the wall thickness is 1004 mm. The inner and outer diameters of the purge chamber are 3750 and 4750 mm, respectively, and the wall thickness is 1004 mm. The wall is a double-layer steel plate–concrete structure; the thickness of the inner and outer steel plates is 22 mm, and the thickness of the concrete is 960 mm. In order to ensure the consistency of the structural calculation and analysis model of the TPC under temperature load, earthquake load, and combined temperature load and earthquake loads, the mesh size of the finite element model used in this paper is kept consistent with that used in the seismic fragility analysis by Liu et al. . Liu et (1)−5/°C [The C40 hematite concrete has a modulus of elasticity of 50,000 MPa , a linea−5/°C , a therm−5/°C , and an (2)−5/°C [The steel plates and studs have a modulus of elasticity of 102,000 MPa, a linear expansion coefficient of 1.2 × 10−5/°C , a therm−5/°C , and an The primary building materials of the TPC include C40 hematite concrete, Q345 steel plates, and SL15 studs. The material parameters required for temperature field analysis are as follows:The temperature range considered in this study is 5–70 °C. The mechanical and thermal parameters vary insignificantly within this temperature range; thus, the effects of temperature on the material parameters were neglected.The indoor air temperature of the TPC is 50 °C during normal operation or shutdown and 70 °C during an accident, which is defined as lasting for 48 h. At these temperatures, the effects of the heat radiation of the structure are insignificant  and can 2∙°C, respectively [The concrete of the TPC is closely bonded with the inner and outer steel plates, and there is continuous temperature and heat flow at the interface. Thus, the interface is defined as a full-contact boundary condition , i.e., tectively .The mechanical boundary conditions for the temperature field analysis of the TPC were defined as follows. The degree of freedom in the vertical displacement of the concrete ground of the structure was constrained, with free deformations allowed for other degrees of freedom.In the normal-operation state of the TPC, it is considered that a steady state has been reached after adequate heat transfer. The temperature field and stress are basically stable. The temperature field of the steel plates is characterized by a uniform distribution. During normal operation, the inner and outer steel plates of the structure have maximum surface temperatures of 35.475 °C and 6.48 °C, respectively. The temperature field of the internal concrete is characterized by a uniform distribution. During normal operation, the inner- and outer-surface temperatures of the concrete are 35.475 and 6.441 °C, respectively. −3 and the maximum compressive strain is 2.04 × 10−3, which exceeded the corresponding values for the ultimate compressive strain and tensile strain of heavy concrete, which are 1.45 × 10−3 and 0.15 × 10−3, respectively. Similarly, the stress responses of the steel plates and studs are significantly higher in this region than in other regions. In particular, the peak stress of the steel plate is 98.305 MPa, which is far below its yield strength of 355 MPa; the peak stress of the stud is 306.725 MPa, which has exceeded its yield strength of 270 MPa, whereas the stress of the studs in other regions was extremely small. During abnormal operation, the internal ambient temperature of the TPC increased from 50 to 70 °C, and the temperature field of the structure was not stable. The transient-state temperature fields in selected regions of the TPC structure were extracted. As shown in As shown in (1)The effects of the temperature load are non-negligible in the design and operation of NPPs, and a temperature load could lead to the concrete cracking and the studs yielding in the TPC structure.(2)Under normal operation, the steady state temperature field significantly affects the stress and strain of the TPC structure, especially for the concrete at the TPC junction.(3)−3, the maximum compressive strain is 2.04 × 10−3, the peak stress of the steel plate is 98.305 MPa, and the peak stress of the stud is 306.725 MPa due to the influence of wall curvature and deformation constraints.During normal operation, the temperature field of the structure changes relatively uniformly, and the temperature gradient along the direction of thickness is 0.245 ℃/cm. Regarding local changes at the connection between the transfer chamber and the cleaning chamber, the maximum tensile strain of the heavy concrete is 8.84 × 10(4)After 48 h of abnormal operation, the temperatures of the inner surface of the heavy concrete of the wall, the inner steel plate of the wall, the outer surface of the heavy concrete of the wall, and the inner steel plate of the wall increase by 8.12, 8.11, 0.31, and 0.30 °C, respectively. The tensile strain of the heavy concrete of the wall increased significantly by 52.64%, and the compressive strain of the concrete increased by 67.33%. The stresses of the studs and steel plates increased by only 1.57% and 6.79%, respectively. Compared with normal operating conditions, there are significantly greater stress–strain increments for concrete than for steel plates and studs under abnormal operating conditions.(5)The distribution of stress and strain in the TPC structure is uneven under the action of temperature load, and there is a relatively serious phenomenon of temperature stress concentration. Affected by the large local curvature of the outer surface of the structure, the stress or strain levels of the outer steel plates, studs, and concrete at the connection between the transfer chamber and the cleaning chamber are even higher than those of other parts. Optimizing this junction or taking other measures to eliminate the temperature stress concentration in this part is recommended.In this study, steady- and transient-state analyses of the heavy-concrete TPC of NPPs under normal operation and after 48 h of abnormal operation, respectively, were performed. The major conclusions are summarized as follows:


Primary outcome was the homeostasis model assessment of insulin resistance (HOMA-IR). Secondary outcomes were fasting glucose, weight, cycle length, lipids, testosterone, adverse effects, quality of life, and depression scores. Median age was 26 years. Body mass was index was 34.4 kg/m2. HOMA-IR was unchanged during MI (p = 0.31) and MET (p = 0.11) . Median fasting glucose changed +0.2 mmol/L during MI (p < 0.001) and −0.1 mmol/L during MET (p = 0.04) (MI vs. MET p < 0.001). Median weight changed −2.3 kg during MI (p = 0.98) and −6.1 kg during MET (p < 0.001) . Median cycle length decreased nine days during MI (p = 0.03) and 13 days during MET (p = 0.03) . High-density lipoprotein (HDL) changed +0.1 mmol/L during MET (p = 0.04) . All other blood parameters and scores of quality of life and depression remained unchanged during MI and MET  . Adverse effects appeared in four women during MI and 16 women during MET . In conclusion, there was no effect on the metabolic outcomes during MI, but positive effects on fasting blood glucose, weight, and HDL during MET. The effect on cycle length was comparable during MI and MET. Adverse effects were less frequent during MI.Polycystic ovary syndrome (PCOS) is associated with insulin resistance. Few randomized controlled trials (RCT) compared myoinositol (MI) with metformin (MET) regarding insulin resistance in PCOS. This was an open-label six-month RCT in women with PCOS ( Polycystic ovary syndrome (PCOS) is an endocrine disorder that affects more than 10% of women of reproductive age . PCOS isMyoinositol (MI) is a naturally occurring insulin sensitizer found in citrus fruits and beans . MI is a2 during MET in obese women with PCOS [Metformin (MET) is a well-known insulin sensitizer ,15. MET ith PCOS . Supplemith PCOS . The mecith PCOS . Qualityith PCOS ,21. Adveith PCOS , and in The effect of MI vs. MET monotherapy on symptoms of PCOS varied in randomized controlled trials (RCT) conducted in women with PCOS not attempting pregnancy ,28,29,30The present aim was to examine MI vs. MET monotherapy in Danish women with PCOS not attempting pregnancy in an open-label, six-month RCT.The participants were recruited through the PCOS outpatient clinic, Department of Gynecology and Obstetrics in collaboration with the Department of Endocrinology, Odense University Hospital (OUH), Denmark. Inclusion criteria were PCOS diagnosed according to the Rotterdam criteria  and age Pausing was required for MET and oral contraceptive pills for at least one and three months, respectively, before study entry. No woman was on MI before the study. Use of barrier contraception or copper intrauterine device during the study was optional. Women getting pregnant during the trial were excluded.®) housed in The Unit for Good Clinical Practice, Odense Patient Explorative Network (OPEN) OUH. The sachets of MI contained 2 mg MI and 200 mg folic acid  and were administered as one dose twice daily. Dose titration of MET was one tablet of 500 mg  twice daily for two weeks followed by two tablets twice daily. Empty packages were counted at the final visit. Examinations were performed at the baseline and six months. Telephone interviews were scheduled after three months to record compliance and adverse effects.The study design was a 6 month open-label RCT. Randomization was conducted through the digital platform Research Electronic Data Capture , Ferriman–Galwey (FG) score, cycle length, gonadothrophins, testosterone, anti-Müllerian hormone (AMH), and scores of QoL and depression as well as adverse effects.Blood samples were drawn in the morning after an overnight fast in the follicular phase in menstruating women, but arbitrarily in women with more than three months of secondary amenorrhea.Serum insulin levels were analyzed by an electrochemiluminescence immunoassay (ECLIA) . Intra-assay coefficient of variation (CV) was 3.2–3.7% and inter-assay CV was 4.2–4.6%. Fasting plasma glucose was analyzed by ultraviolet hexokinase analysis-based absorption photometry . CV was 2.4%. Plasma high-density lipoprotein (HDL) cholesterol, total cholesterol, and triglycerides were analyzed by enzymatic colorimetric analysis-based absorption photometry , and low-density lipoprotein (LDL) cholesterol was calculated using the Friedewald equation. CVs were 1.3–2.3%. Sex hormone binding globulin (SHBG) was analyzed by chemiluminescence in a sandwich assay . CV was 4.7%. Plasma total testosterone was analyzed by liquid chromatography tandem mass spectrometry . CV was 3.3%. Free testosterone was calculated based on the Vermeulen equation with a standard albumin value of 4.3 g/dL . AMH, FSMenstrual cycle length was self-reported in a menstrual cycle calendar. Polycystic ovaries (PCO) were determined by vaginal ultrasound as the preference. Abdominal ultrasound was chosen by some women for personal reasons.Hirsutism was evaluated by the modified FG scoring system .Adverse effects and pregnancies were registered throughout the study using a personal diary.Two self-reportable, validated, Danish versions of the generic questionnaires were administered at the baseline and six months. The Short Form Health Survey (SF-36) explores eight areas: physical functioning, role limitations due to physical health, role limitations due to emotional health, energy/fatigue, emotional well-being, social functioning, pain, and general health. Each category is scored on a scale from 0–100, where higher scores indicate better functioning. The ICD10 Major Depression Inventory (MDI) is a rating scale to measure the degree of depression, where <20 is no depression and 50 indicates severe depression.p-value of at least 0.05 was considered statistically significant. Data are presented as the median and interquartile range (IQR) .For power calculation, the type 1 error was set to 0.05, and the type 2 error was set to 0.1. The six-month RCT of MI and MET in insulin-resistant women with PCOS was used as a reference for the power calculation . Assumpthttps://www.clinicaltrialsregister.eu/ctr-search/search?query=2016-004506-34+ (accessed on 26 January 2017)), registration number (EudraCT) is 2016-004506-34. The date of registration was 11 November 2016. The first patient was enrolled 25 April 2017. The end of the trial was 29 October 2021.Participants gave their written informed consent after oral and written information. The Local Ethics Committee and Danish Medicines Agency approved the study, approval code S-20160188, date of approval 27 February 2017. The trial complied with the Declaration of Helsinki and standards for Good Clinical Practice. The Clinical Trials Register   . At the  n = 12) .p = 0.09) (p < 0.001), and decreased in the MET group, −0.1 mmol/L (p = 0.04), and the Δ-values were different between MI vs. MET (p < 0.001). Median HDL cholesterol was unchanged in the MI group, but increased in the MET group, 0.1 mmol/L (p = 0.04), and the Δ-values were comparable between MI vs. MET (p = 0.07). For all other lipids, the median within-group changes were non-significant (NS) and the Δ-values were comparable.HOMA-IR was unchanged within the MI and MET groups and Δ-values were comparable between MI vs. MET ( = 0.09) . Median p < 0.001) and 2.4 kg/m2 (p < 0.001), respectively, in the MET group and Δ-values were different between MI vs. MET (both p = 0.02) (p ≥ 0.11). HOMA-IR Δ-values and weight Δ-values were correlated, but only significantly for the MI and MET groups combined, r = 0.51 (MI) (p = 0.08), r = 0.54 (MET) (p = 0.13), and r = 0.53 (MI and MET combined) (p = 0.01).The weight and BMI did not change significantly in the MI group, but decreased 6.1 kg ( = 0.02) . Waist ap = 0.03) and 13 days in the MET group (p = 0.03), and the Δ-values were comparable between MI vs. MET (p = 0.92) (The reduction in cycle length was 9 days in the MI group ( = 0.92) . p = 0.49)  .p = 0.04) due to a nonsignificant increase of LH during MI (p = 0.15) and a nonsignificant decrease of LH during MET (p = 0.16)  . For then = 2), irregular menstruation (n = 1), and GI side effects (n = 1). One woman withdrew from the study due to adverse effects: irregular menstruation .Adverse effects were registered in four women during MI: headache (n = 1), mood swing (n = 1), increased body hair (n = 2), and GI side effects (n = 12). Five women withdrew from the study due to adverse effects: GI side effects (n = 3), headache (n = 1), and mood swings (n = 1); MI vs. MET regarding adverse effects (p < 0.01), MI vs. MET regarding GI side effects (p < 0.01), and MI vs. MET regarding withdrawal (p < 0.001).Adverse effects were registered in 16 women during MET: headache , pregnancy (MI n = 0 and MET n = 4), and adverse effects , MI vs. MET (p < 0.01) (p = 0.01), lower emotional well-being score, 64 vs. 72 (p = 0.03), and higher MDI score, 27 vs. 12 (p = 0.02).Reasons for noncompletion were low compliance  . Non-comScores of QoL and depression did not change significantly in any of the groups and the Δ-values were comparable .In the present RCT, we compared MI and MET in a well-characterized Danish group of women with PCOS outside a fertility setting. The main finding was that MI did not improve the metabolic study outcomes since HOMA-IR, Hb1Ac, insulin, and weight remained unchanged and fasting glucose even increased during MI treatment. In contrast, MET had beneficial effects on fasting glucose, HDL cholesterol, and weight. MI and MET had a comparable and positive effect on the menstrual cycle length. The present study design included medical intervention without lifestyle intervention, which allowed us to observe the isolated effect of MI vs. MET on the study outcomes and adverse events.2) was found in the Italian six month RCT [2) [Unchanged HOMA-IR  and weigonth RCT . Remaini RCT [2) ,30 or a  RCT [2)  during M RCT [2) . AlthougMET was associated with a 6.8% decrease in BMI in our study, which matched the results from a recent meta-analysis . FurtherCycle length decreased to a comparable extent during MI and MET; nine and 13 days, respectively. Decreased cycle length during MI and MET corresponded to results from previous RCTs of MI vs. MET monotherapy in PCOS ,24. CombAdverse effects were generally milder and less frequent during MI than during MET. Most remarkably, GI side effects were reported by one woman only during MI, whereas GI side effects were reported by 14 women during MET. Three women withdrew from the study due to GI side effects during MET. Our results correspond to the findings of the RCTs that reported results on adverse effects during MI vs. MET ,24. In tScores of QoL and depression were unchanged during MI and MET in the present study. In contrast, one previous 12-week RCT showed significantly improved QoL during MI and MET in PCOS, but the effect was small and could be of minor clinical relevance . BaselinStrengths and limitations apply to the present study. The strength of the present study was the RCT design with study outcomes covering the metabolic and hormonal phenotypes of PCOS and quality of life. The study was powered to determine non-inferiority of MI vs. MET regarding HOMA-IR, but results regarding secondary metabolic outcomes were consistently in favor of MET. The study population had no specific requirements for participation other than PCOS . The study design resembled average outpatient management including telephone contact after three months. Drop-out rate was high, which could be related to the lower scores of QoL and depression in non-completers. Psychosocial support could have increased study completion, but would not resemble the resources of the usual health care systems.In conclusion, HOMA-IR and weight were unchanged during MI whereas MET had beneficial effects on weight, fasting blood glucose, and HDL cholesterol. Cycle length decreased to a similar extent during MI and MET. Adverse effects were less frequent during MI vs. MET. MI may be considered as a second line treatment of oligomenorrhea in PCOS, if MET is not tolerated and oral contraceptives are not requested.


In this study, the bond–slip behavior between a new type of M-section steel skeleton  applied in assembled shear wall structures and concrete was investigated. First, push-out tests were conducted on 21 M-section steel–concrete (MSSC) specimens, wherein the effects of the concrete cover, concrete strength, and anchorage length on the bond strength between the M-section steel and concrete were considered. Further, the crack patterns, strain distribution of M-section steel, and bond–slip curves of the MSSC specimens were investigated using conventional strain measurement and a non-contact optical three-dimensional deformation measurement system, Digital Image Correlation-3D (DIC-3D). The experimental results demonstrated that the bond–slip curves of the MSSC specimens were divided into four stages: the linear ascending, non-linear ascending, non-linear descending, and residual stages. The initial average bond strength  With the advances in building industrialization, assembled lightweight steel forming skeletons have been applied in shear wall structures due to their characteristics of high stress-efficiency, seismic energy-efficiency, and environmentally friendly protection ,2,3. HowChen et al.  considerTo study the bond strength between M-section steel and concrete, 21 push-out specimens were analyzed. The effects of the concrete cover, concrete strength, and anchorage length on the bond strength between the M-section steel and concrete were considered. Thereafter, based on the experimental results, a bond–slip constitutive model between the M-section steel and concrete was proposed. A numerical simulation was conducted using the proposed constitutive equation, which demonstrates that the proposed equation better predicted the damage process of the entire specimen.Liu et al. ,22,23 coTherefore, the influence of concrete strength  at the upper bearing of the test machine, which was used to the measure the relative slip at the loading end, as shown for LVDT-1 in The LVDT, strain gauges, and force transducer data were obtained using the Donghua dynamic signal acquisition system (DDSAS)  at QinghTo obtain the surface strain distribution pattern of the M-section steel, strain gauges were deployed at the web and flange of the M-section steel, as depicted in When loaded to 60–80% of the ultimate load, the specimens exhibited slight vertical cracks along the anchorage length on the east and west sides. However, specimens with thicker concrete covers did not show any cracks, such as MSSC-01 and MSSC-02.On being subjected to the ultimate load, the specimens produced a large cracking sound, the load suddenly decreased, and the slip of the free end increased significantly. At this point, all the specimens exhibited vertical penetration microcracks in the direction of the anchorage length on the east and west sides, which were located approximately in the middle of the M-section steel flange. Further, vertical microcracks started at the free end and extended to the loading end. Certain specimens also formed new small branching cracks in the direction of the anchorage length on the east and west sides, such as MSSC-02, MSSC-03, MSSC-05, and MSSC-06.Subsequently, the load decreased significantly. When the load dropped to approximately 20–30% of the ultimate load, cracks in the 45° direction gradually appeared on the concrete surface at the loading end (located at the corners of the M-section steel flanges and the corners of the web reinforcement rolls). Consequently, it exhibited a tendency to extend in all directions. In addition, certain specimens exhibited horizontal cracks along the lateral edges of the M-section steel and web, for example, MSSC-01, MSSC-03, and MSSC-06. However, the vertical microcracks along the length of the anchorage on the east and west sides also expanded outwards. With the increase in slippage of the loading and free ends, the load decreased relatively slowly, and eventually, tended to be horizontal. At this moment, the mechanical bite force and frictional resistance force provided bond strength between the M-section steel and concrete. During this process, cracks developed, and the existing cracks extended rapidly. Most of the specimens exhibited penetrating diagonal cracks on the concrete surface at the loading end. The crack width also gradually increased, and the branch cracks on each side penetrated each other owing to the development of the branch cracks. Finally, it resulted in concrete spalling at the free-end corners of certain specimens. Further, the crack widths were also measured and reached a maximum width of 3–5 mm, with longitudinal splitting cracks predominating.① crack in ① crack started to appear when the load decreased to approximately 20% of the ultimate load and continued to extend outwards. Certain specimens showed cracks extending to their surface. In addition to the type ① crack, the crack pattern of the specimen can be divided into three categories:According to the failure pattern of the specimens, each specimen was found to exhibit oblique cracks at the web reinforcement-roll edge and the corner of the web. This is because of the presence of the web reinforcement-roll edge and holes in the web, which hinder the tendency of the M-section steel to slide downwards. Thus, diagonal tearing failure is generated in the concrete, as shown by the type (1) Diagonal crack: First, the specimen developed a through-crack on the east and west sides from the outside towards the inside of the concrete. With the increase in the slip of the loading end, diagonal cracks gradually started to develop on the rolled edges and corners of the connecting section of the M-section steel. They were roughly oriented towards 45° and tended to extend outwards. In the case of certain specimens with a thinner concrete cover, this type of crack penetrated the surface of the specimen. Most specimens exhibited a diagonal crack as the final failure pattern, as illustrated in (2) Parallel crack: Similarly, this type of crack first generated a through-crack on the east and west sides of the concrete from the outside towards the inside. Subsequently, a horizontal crack developed in the middle of the M-section steel connecting section from the inside towards the outside, and continued through to the surface of the specimen. In addition, parallel cracking was mainly observed in specimens with a thicker concrete cover and higher concrete strengths, as shown in (3) Composite crack: This crack development pattern is complex and is generally a combination of the two crack patterns described above. First, the specimen exhibited two through-cracks on the east and west sides of the concrete from the outside to the inside. Subsequently, an oblique crack in the direction of approximately 45° appeared and extended outwards at the corner of the rolled edge and the connecting section of the M-section steel. In addition, a microcrack developed in the middle of the M-section steel web and extended towards the south and north sides. Finally, with the increase in the slip of the loading end, a roughly vertical through-crack was observed in the middle of the M-section steel web, as depicted in Using the DIC-3D scattering technique, To analyze the strain variation on the surface of the M-section steel, it was assumed that the strain was the same at the same horizontal position for the inside and outside of the flange, web, and symmetric positions. Because of the rapid unloading of the specimens after reaching the ultimate load, the strain gauges experienced significant failure. Therefore, To ensure the accuracy of the data, the results of each set of specimens were averaged to obtain the load–slip curve, as shown in Pu, that is, the initial load Ps, which corresponded to the slip value of Ss.(1) Linear ascending stage (OA): In the early stages of loading, the specimen initially developed a small slip near the loading end, which caused a gradual reduction in its chemical adhesive force, and the cementitious colloid sheared off. Further, the internally broken concrete layer increased in volume compared with the previous volume of the concrete layer owing to the presence of pores. This resulted in normal stress between the M-section steel and concrete, which generated a frictional resistance force and mechanical bite force. Simultaneously, new chemical adhesive forces developed in the bonding area where no slippage occurred. The newly generated chemical adhesive force, frictional resistance force, and mechanical bite force carried the external load together, which enabled the specimen to bear a stronger external load. During this phase, the slip at the loading end was approximately linearly related to the load. The magnitude of the load corresponding to point A was approximately 40–50% of the ultimate load Su, the load reached point B, which was the ultimate load Pu. In addition, vertical through-cracks were generated on the east and west sides of the concrete at this point.(2) Non-linear ascending stage (AB): When the load reached inflection point A, the load–slip curve exhibited a change from the previously linear to a non-linear growth. Within this phase, the chemical adhesive force remained at a constant value in the bonding area where there was no slippage; however, the frictional resistance force and mechanical bite force in the zone where slip occurred were slowed down owing to the continuous cracking and breaking within the concrete. The slip growth rate was faster than the bond growth rate. Consequently, the slope of the curve gradually decreased, and the upward convexity became increasingly obvious. Subsequently, the bonded section without slip was gradually transferred from the loading end to the free end. When the slip reached Sr, there was a tendency for the load to level off, that is, the residual load Pr, which corresponded to a load size of approximately 30–60% of the ultimate load Pu.(3) Non-linear descending stage (BC): After the load reached its peak, the chemical adhesive force was gradually lost with the continuous increase in the amount of slip. Although the frictional resistance force and mechanical bite force still increased, the increase was much smaller than the loss of the chemical adhesive force. Thus, the load–slip curve exhibited a gradual downward trend. At this stage, the slip had more space to develop as vertical through-cracks developed on the east and west sides of the concrete. However, because of the presence of M-section steel web holes and reinforced rolled edges, normal and shear stresses were generated on the concrete. Consequently, the combined effect of the above-mentioned forces caused diagonal cracks to appear on the surface of the concrete, which continued to extend outwards. Once the slip value reached (4) Residual stage (CD): As the contact surface of the M-section steel and concrete gradually smoothed, the crack development stabilized, and the frictional resistance and mechanical bite forces tended to attain a constant value. The load–slip curve was approximated to a horizontal line or a slightly decreasing curve . With a further increase in the slip, the M-section steel was pushed out. Finally, the specimens were subjected to damage.To obtain the average bond–slip curve, namely the Ss, ultimate slip value Su, and residual slip value Sr, respectively. This curve reflects the basic characteristics of the bond strength of M-section steel to concrete, as shown in According to Equation (1), three corresponding average characteristic bond strength values can be obtained: the average initial bond strength To analyze the respective effects of concrete strength, anchorage length, and concrete cover on the bond strength of M-section steel to concrete, a single-factor linear regression analysis was performed on the characteristic average bond strengths derived from the tests, as illustrated in The relationship between the concrete strength and the characteristic average bond strengths is shown in The statistical regression analysis of the influencing factors revealed that the average initial bond strength Ss, ultimate slip value Su, and residual slip value Sr. The test results indicated that the initial slip value Ss was primarily influenced by the concrete cover and strength of the concrete, in addition to the above two influencing factors, while the ultimate slip value Su and residual slip value Sr were also influenced by the anchorage length. Based on the analysis above, the regression equation for the characteristic slip values was established as follows:To obtain the bond–slip constitutive model of the MSSC, three characteristic slips were also defined according to the experimental Using the characteristic average bond strength and characteristic slip values defined in the previous section, the a = b = 0.(1) Linear ascending stage (OA): At this stage, the average bond strength tended to increase linearly with the amount of slip. Therefore, the description is given in a straight line as follows:p = q = (2) Non-linear ascending stage (AB): During this phase, the average bond strength tended to increase non-linearly with the amount of slip. Thus, a hyperbolic curve is used to describe it:m = n = (3) Non-linear descending stage (BC): During this phase, the average bond strength tended to decrease non-linearly with the amount of slip. Therefore, a hyperbolic curve is used to describe this phase:(4) Residual stage (CD): With an increase in slip, the average bond strength remains essentially constant, which can be described by a straight line at this stage:To examine the degree of curve fitting, To further investigate the reasonableness of the proposed constitutive relationship, this section presents additional validations performed by simulating a push-out test using the finite element software ABAQUS 2020. Owing to the complexity of the internal bonding mechanism of the MSSC specimen, convergence with the standard solution is difficult. Therefore, a quasi-static analysis of 21 MSSC specimens was conducted using the explicit dynamic solution method. Further, to ensure the accuracy of the results, the overall kinetic energy of the specimen must be maintained below 10% of its internal energy . ExploitThe element type and meshing of the finite element model are presented in To define the interaction of the concrete with M-section steel and concrete-to-steel plates, the general contact provided in ABAQUS was used. The details of the finite-element contact between the M-section steel and concrete are illustrated in Owing to the symmetry of the specimen in the YZ plane, all the nodes on the symmetry plane of the MSSC specimen are limited in terms of translation in the X-direction and rotation in the Y- and Z-directions, as shown in Ψ is the dilation angle, Kc is the ratio of the second stress invariant to the tensile meridian [During the FEA, a plastic-damage model (CDP) was used for concrete. This damage model is based on a plastic continuous medium and assumes tensile cracking and compressional crushing of the concrete material as its main failure mechanisms, with equivalent tensile plastic strain and equivalent compressive plastic strain controlling the evolution of the failure surface . The basmeridian . The uniectively .A bilinear strengthening model was used for M-section steel . It was cos I and cos II are directional cosines, as shown in Equations (19) and (20), In the finite element program ABAQUS, two modeling methods are provided for the interaction behavior of interfaces, namely cohesive-element and cohesive-contact . The cohα indicates the B-K parameter.For damage evolution, the Benzeggagh-Kenane (B-K) form based on energy is used , with thD, which is expressed as follows:The degradation of the interface stiffness was described by introducing damage parameter α. In this study, according to the obtained bond–slip curve and the parametric analysis of the finite element model, setting ======α = 2 [In summary, there are only seven unknown parameters in the above equation: nd α = 2 ,45 can bThe results of the FEA of 21 MSSC specimens were calculated and compiled to obtain a comparative analysis of the FEA and EXP bond–slip curves, as shown in However, the M-section steel did not buckle, and the FEA results confirmed that the M-section steel entered a plastic state, as illustrated in In this study, push-out tests were conducted on 21 MSSC specimens to investigate the effects of the concrete cover, concrete strength, and anchorage length on the bond strength of the M-section steel to concrete. The failure patterns of the MSSC specimens were analyzed, and the displacement and strain variation states of the specimens were investigated using a non-contact optical three-dimensional deformation measuring instrument, DIC-3D. Thereafter, the bond–slip constitutive equation for M-section steel to concrete was proposed. Further, to verify the reasonableness of the constitutive equation, a comparative analysis of the experimental results was performed. In addition, to reproduce the entire failure process of the MSSC specimen, the proposed constitutive equations were simulated numerically. Based on the results of the experiments and numerical simulations, the following conclusions were drawn.Depending on the final failure pattern of the MSSC specimen, the crack pattern could be divided into three main types: diagonal, parallel, and composite cracks. The diagonal crack occurred mainly in specimens with a thinner concrete cover and was the predominant crack pattern. Parallel cracks were mainly observed in the specimens with a greater concrete cover thickness and higher concrete strength. However, the composite crack development pattern was more complex and occurred only in a few specimens.The DIC-3D scattering results showed that the displacement variation of the MSSC specimen in the X-direction was symmetrically distributed, and the specimen was mainly deformed in the X-direction, whereas the Y-direction and Z-direction had an obvious restraining effect on deformation in the X-direction.The load–slip curve of the MSSC specimen was divided into four major stages: the linear ascending, non-linear ascending, non-linear descending, and residual stages. In the early stages of loading, the specimen initially slipped slightly near the loading end where the bond strength was mainly supplied by the chemical adhesive force, but no cracks were produced. With the increase in the amount of slip, cracks gradually emerged on the concrete surface, and the load reached the ultimate peak Pu when vertical through-cracks appeared on the concrete sides. With a further increase in slip, the chemical adhesive force was gradually lost, while the frictional resistance and mechanical bite forces gradually increased. However, the growth was much less than the loss of chemical adhesive force, which resulted in a non-linear decrease in the load and the amount of slip. Consequently, when the load decreased to a certain value, it ceased to grow, reaching the residual load Pr. Here, the bond strength was mainly provided by a combination of frictional resistance and mechanical bite forces.Through a linear regression analysis of the test results, it was observed that the initial average bond strength To further validate the reasonableness of the proposed bond–slip constitutive equation of M-section steel to concrete, numerical simulations were performed on the MSSC specimens. The results showed that the numerical simulation can better predict the entire failure process of the specimen. Moreover, the bond–slip curves obtained through the numerical simulation were consistent with the test results, thereby indicating the reliability of the constitutive relationship.


X, Pb, and SO2) were minimized. In addition, the review assesses future researcher guidelines for concrete with RDM to improve performance.Every year, millions of tons of red mud (RDM) are created across the globe. Its storage is a major environmental issue due to its high basicity and tendency for leaching. This material is often kept in dams, necessitating previous attention to the disposal location, as well as monitoring and maintenance during its useful life. As a result, it is critical to develop an industrial solution capable of consuming large quantities of this substance. Many academics have worked for decades to create different cost-effective methods for using RMD. One of the most cost-effective methods is to use RMD in cement manufacture, which is also an effective approach for large-scale RMD recycling. This article gives an overview of the use of RMD in concrete manufacturing. Other researchers’ backgrounds were considered and examined based on fresh characteristics, mechanical properties, durability, microstructure analysis, and environmental impact analysis. The results show that RMD enhanced the mechanical properties and durability of concrete while reducing its fluidity. Furthermore, by integrating 25% of RDM, the environmental consequences of cumulative energy demand (CED), global warming potential (GWP), and major criteria air pollutants (CO, NO Gibbsite is accelerated when the fluid is cooled and seeded with fine-grained aluminium hydroxide precious stones from previous extractions after partitioning the accumulation by sifting. The RMD process is seen in Bauxite is a mineral composed of hydrated aluminium oxides and mixtures of other elements, such as iron. The aluminium mixtures in the bauxite may be found in many kinds of aluminium parts, and contaminations may influence extraction conditions. Aluminium oxides and hydroxides are amphoteric, which means they are acidic and fundamental at the same time. AlThe chemical difference in every circumstance, applying RMD is a challenge. However, detecting the RMD features for each location where it is created and establishing a template as a foundation is achievable. Two variables influence the quantity of RMD produced. The first pertains to the ore quality, while the second refers to the processing conditions. The amount of RMD produced has been approximated by many writers. The reported values vary from 0.3 to 2.5 tons per ton of poorer grade bauxite treated . Patents2, C4AH13 and C4AH11 are the hydrates framed after 4 days. Later investigations have confirmed these findings. When compared to fly powder, RMD does not impart much compressive quality, although flexural quality and resistance to porousness have been seen in RMD bond concrete. Despite the fact that RMD is less accessible than flies’ fiery remnants, it is critical to use or reuse RMD since it has several harmful ecological effects [RMD affects agricultural landscapes due to its strong alkalinity, hence, it should be cleaned numerous times before usage. There is a chance that the RMD lake may leak. If it is organized underground, it pollutes the ground water table. Based on the writing overview, RMD fills in as an excellent folio material and has proven to be a decent cementation material. The tiny pores of cement are diminished by RMD, and as the amount of RMD in solid increments increases, the amount of water swallowed decreases. A basic combination of 70% RMD and 30% CaO yields a product with a compressive quality of 7 MPa. Ca(OH) effects .2 and Na2O are also important. In addition to aluminium hydroxide and a complicated Na5Al3CSi3O15 phase, XRD detects several of these oxides. Different researchers have reported different chemical compositions, as can be shown in The use of RMD in the manufacturing of concrete as a cement substitute has a number of environmental and economic advantages, including minimizing soil and groundwater contamination, reducing dust pollution, conserving natural resources for cement clinker, and lowering the cost of concrete production. The purpose of this paper is to present a detailed review of current progress on the use of RMD in concrete production, as well as to clearly point out four directions for using RMD in concrete production, namely, fresh properties, mechanical properties, durability aspects, and environmental aspects. Furthermore, the review also evaluates the future researcher guideline for better performance.As indicated in 3, whereas the fresh density ranges from 1752 to 1844 kg/m3. When RDM concentration in concrete is raised, the specific gravity of the concrete drops. The specific gravity of the concrete specimen having 25% RDM is around 5% lower than the reference specimen with 0% RDM, according to the findings [findings . In contfindings .The addition of RMD has the effect of speeding up the setting process, as shown in The presence of aluminium and sodium hydroxides, which are known as accelerators , might eThe TS of concrete with different substitution ratios of RDM is shown in 2 crystals were fractured into multiple tiny crystals and less orientated in the RMD-based cement hydration process, which leads to minimizing pore connections and water absorption, according to Manfroi et al. 2014 [As indicated in al. 2014 . Due to al. 2014 . Overallal. 2014 . The resal. 2014 ,80 in teal. 2014 , high-quThe resistance of the samples to chloride ion penetration was determined by testing the chloride permeability of the RDM-based concrete. The RCPT was performed in accordance with ASTM C 1202  and the 0.5 (control) to 0.266 mm/min0.5 (20% RDM) which is ascribed to the fineness of RDM, which makes the concrete surface extremely thick by filling all the spaces. This filling property would aid in the development of a continuous pozzolanic reaction between RMD and cement, improving the strength and durability of concrete over time. As C–S–H filled all of the capillary holes during hydration, microstructure analysis indicated that replacing RMD in concrete lowered sorptivity values. This occurs because RMD fills holes and cracks in concrete, which results in lower sorptivity [With an increase in the degree of RMD replacements in concrete, the sorptivity values displayed in rptivity .The surface resistivity test may be performed to determine the electrical resistivity of water-saturated concrete and provide a quick indication of its resistance to chloride ion penetration. The resistance to current leakage along the surface of insulating material is characterized by the substance’s surface resistivity. A voltage is transmitted between the two electrodes and a test specimen is placed between them. A resistivity meter is used to determine the value . The surThe area between aggregate and paste is known as the interfacial transition zone (ITZ). When a porous fracture separates the two locations, the ITZ is at its weakest. The ITZ is highly established and must correspond to strong strength if there is just a little fracture evident or it virtually seems like one uniform surface. When cement is hydrated, quartz and calcium oxide react, assisting in the development of CSH gel. The presence of larnite and hatrurite in the red mud concrete provides conclusive proof that CSH gel was formed, giving the concrete strength qualities. According to research , the Ca/EDS was employed on the hardened cement paste samples during the SEM investigation. This would allow researchers to establish what compounds appear and whether the structure is modified significantly when RMD concentration increased compared to the control. Since calcium hydroxide intensity impacts the Ca/Si ratio of the CSH and the creation of the CSH network, the calcium/silicon (Ca/Si) ratio was tested to see how effectively the cement had formed . CSH is 2 vs. RDM replacement in concrete. As can be shown in 2 from 556.8 to 409.9 kg·m3. As a result, CO2 rises in proportion to the amount of cement. In general, it can be said that cement is the source of the most CO2 releases. As a result, even when delivery distances are much larger than the cement delivery distance, the usage of RDM is viable.2 discharges per unit volume of concrete per 28-day strength characteristics (compressive and tensile) for the concrete employed in the research are displayed in 2 discharges normalized by various strength qualities including RDM up to 20% substitute is less than the intensity of CO2 emissions for a reference specimen with no RDM.The concentration of COThe energy needed throughout the life cycle of lightweight concrete is shown by CED in this research. X, Pb, and SO2 decreased by roughly 32.5 percent, 17.1 percent, 31.8 percent, and 22.4 percent, respectively, as compared to 0 percent RDM. In general, the primary criterion air pollutants of CO, NOX, Pb, and SO2 rise with increased cement concentration owing to fuel-burning during the pyro processing step.The comparison of normalized main criterion air pollutants in concrete with varying RDM concentrations is displayed in The use of RMD as a cement substitute provides a variety of environmental and economic benefits, including reduced soil and groundwater contamination, reduced dust pollution, conservation of natural resources for cement clinker, and lower concrete construction costs. The goal of this analysis is to provide a comprehensive overview of current progress in the use of RMD in concrete production, as well as to clearly identify four directions for using RMD in concrete production: fresh properties, mechanical properties, durability aspects, and environmental aspects. The detailed conclusion is given below.The chemical composition of RDM shows that it can be used as pozzolanic material.The flowability of concrete decreased as the substitution ratio of RDM increased due to its porous nature.Mechanical performance such as compressive strength, flexural strength and TS improved with the substation of RDM up to a certain level. Maximum CMS was achieved at 10% substitution of RDM which is 43% higher than reference concrete compressive strength. Further, the substitution of RDM results in the decreased mechanical performance of concrete. Therefore, finding an optimum is important for maximum performance. Different researchers recommend a different optimum dose of RDM. This might be possible due to different sources of RDM. However, the majority of researchers recommend 10 to 15% substitution of RDM as an optimum dose.Water absorption and chloride permeability decreased concrete considerably with substitution RDM. However, less information is available in this regard.The velocity of ultrasonic waves is reduced when the RDM concentration is increased.SEM results show that the substation of RDM improved the interfacial transition zone (ITZ). It is a result of the micro filling effect of RDM which fills the crack (ITZ), leading to more dense concrete.EDX results ensure the pozzolanic activity, creating additional compounds (CSH), which enhanced the cementitious properties of the paste.2, a rate of worldwide warming, reduces from 556.8 to 409.9 Kg·m3 as RDM content rises from 0% to 25%, showing that concrete sustainability improves as RDM content increases.COX, Pb, and SO2 are reduced by around 31%, 32.5 percent, 31.8 percent, 17.1 percent, and 22.4 percent, respectively.When the RMD content is increased from 0% to 25%, the amounts of CED, CO, NOOverall, the analysis reveals that RDM has the potential to be used as a cement substitute. Decreased soil and groundwater contamination, reduced dust pollution, conservation of ecological assets, and cheaper concrete production costs are some of the environmental and economic advantages of using RMD as a cement alternative in concrete manufacturing.Fewer data are accessible on durability aspects particularly dry shrinkage and creeps. Therefore, this review recommends a detailed investigation of dry shrinkage and creep properties of concrete with RDM.Different methods, such as thermal activation or alkali activation, should be applied to improve the pozzolanic activity of RDM.Thermal conductivity and heat insulation characteristics with RMD should be investigated in detail.Although RDM improved the strength of concrete, but concrete is still weak in tension. Therefore, this review also recommends fibers in RDM-based concrete to enhance the tensile capacity.