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Reinforced concrete (RC) buildings have suffered severe damage in the past due to inadequate lateral force resistance or energy dissipation capability. There is a need to improve the seismic performance of existing, vulnerable RC structures, particularly those that were either not initially intended for seismic effects or were planned to an obsolete seismic standard. Friction dampers are a revolutionary technique for improving lateral force resistance and energy dissipation capacity in the seismic retrofit of RC buildings. In this study, energy dissipation in seismically retrofitted RC buildings using friction dampers is investigated. An investigation of the nonlinear response history was performed after friction dampers were applied to the RC building. The analysis results indicate that the peak story drift ratios are reduced and constant throughout the height of the building, which may be a sign that the structure has not suffered soft story damage. In addition, the total friction damper’s energy-dissipation is half of the total input energy.

Background Despite the legalization of cannabis use for medical purposes in Thailand in February 2019, illicit providers are still widespread and accessible. This study aimed to understand why people still chose to receive medical cannabis treatment or products from unlicensed or illegal providers. The practices of unlicensed or illegal providers in provision of medical cannabis products or treatment services were also examined. Methods Qualitative in-depth interviews were conducted among medical cannabis providers and users, including 36 unlicensed and 7 licensed providers and 25 users in 2019-2021. Snowball sampling was used to recruit participants until saturation of data was achieved. Interviews included open-ended questions about the providers’ practices and attitudes towards medical cannabis. Interviews were recorded and transcribed, and thematic analysis was performed. Results Overall, six reasons were identified to answer why unlicensed/illicit providers were still popular, including: 1) easy accessibility; 2) familiarity with the unlicensed providers before the legal scheme became available; 3) favorable characters (kind, supportive, non-judgmental) of unlicensed providers; 4) affordable treatment fees; 5) trust in the quality of the medicines; and 6) lack of knowledge and negative attitudes towards cannabis from healthcare professionals. Most providers started their career as medical cannabis providers by using it themselves or with their relatives and being satisfied with the results. They used cannabis products to treat all diseases, including skin, eyes, HIV/AIDS, non-communicable diseases and all kinds of cancers. Additionally, they believed that it was effective, with no or minimal adverse effects. Conclusions This study suggests that some patients will continue receiving medical cannabis treatment and products from unlicensed or illegal providers. More attention should be paid on increasing the capacity of medical cannabis service systems within public health hospitals, and the certification of unlicensed providers, so as to integrate them into a regulated system.

Recent earthquakes have highlighted the need to strengthen existing structures with substandard designs. NFRPs provide a sustainable, cost-effective alternative for strengthening, but accurately predicting their performance remains a challenge. This study investigates the use of machine learning algorithms for predicting the compressive strength concrete specimens confined with various NFRPs. Four algorithms were employed: decision tree, random forest, neural network, and gradient boosting regressor. A diverse dataset encompassing various geometries, material properties, and confinement configurations was used to train and evaluate the models. Gradient boosting regressor (GBR) achieved the highest performance, with an average R-squared value of 0.94 and low mean absolute error (MAE) and root mean squared error (RMSE) during training and k-fold cross-validation. Neural network and random forest also demonstrated satisfactory performance, with average R-squared values of 0.88 and 0.86, respectively, during cross-validation. These results suggest that machine learning holds promise for predicting the compressive strength of concrete confined with NFRPs. GBR offers the most accurate predictions, making it a valuable tool for engineers seeking to optimize the design and performance of strengthened structures using sustainable materials.

This paper presents a comprehensive investigation into the behavior of concrete confined with hybrid Basalt and Chopped Strand Mat (B-CSM) fibers. The newly proposed B-CSM confinement technique substantially enhances the brittle compressive stress-strain behavior, leading to a noteworthy increase in peak strength (approximately 90%) and ultimate strain (approximately 461 %). The efficiency of B-CSM confinement is affected by the strength of plain concrete, with lower-strength specimens indicating a more pronounced enhancement. The performance of existing analytical models for FRP confinement in predicting ultimate strength and strain in B-CSM confined concrete is assessed, highlighting the need for tailored models. Regression-based equations are proposed for characteristic points along the stress-strain curve, enabling accurate prediction of material behavior. The predicted stress-strain curves exhibit a high level of agreement with experimental results. These findings provide valuable insights for the design and application of B-CSM confinement techniques in structural engineering, facilitating improved performance and ductility of concrete structures under compressive loading conditions.

Abstract Background In vitro drug susceptibility assay of Plasmodium falciparum field isolates processed “immediate ex vivo” (IEV), without culture adaption, and tested using histidine-rich protein-2 (HRP-2) detection as an assay, is an expedient way to track drug resistance. Methods From 2005 to 2010, a HRP-2 in vitro assay assessed 451 P. falciparum field isolates obtained from subjects with malaria in western and northern Cambodia, and eastern Thailand, processed IEV, for 50% inhibitory concentrations (IC50) against seven anti-malarial drugs, including artesunate (AS), dihydroartemisinin (DHA), and piperaquine. Results In western Cambodia, from 2006 to 2010, geometric mean (GM) IC50 values for chloroquine, mefloquine, quinine, AS, DHA, and lumefantrine increased. In northern Cambodia, from 2009–2010, GM IC50 values for most drugs approximated the highest western Cambodia GM IC50 values in 2009 or 2010. Conclusions Western Cambodia is associated with sustained reductions in anti-malarial drug susceptibility, including the artemisinins, with possible emergence, or spread, to northern Cambodia. This potential public health crisis supports continued in vitro drug IC50 monitoring of P. falciparum isolates at key locations in the region.

Objective: To investigate the effects of Δ9-tetrahydrocannabinol, the principal psychoactive compound of Cannabis sativa, and cannabinol, a Δ9-tetrahydrocannabinol degradative product, on human non-small cell lung cancer cells. Methods: Δ9-Tetrahydrocannabinol and cannabinol were tested for anticancer activity in human non-small cell lung cancer (A549) cells. The effects on cell proliferation, apoptosis, and phosphorylation profiles were examined. The effects of Δ9-tetrahydrocannabinol and cannabinol on tumor growth were also investigated using a xenograft nude mouse model. Apoptosis and targeted phosphorylation were verified by immunohistochemistry. Results: Δ9-Tetrahydrocannabinol and cannabinol significantly inhibited cell proliferation and increased the number of apoptotic cells in a concentration-dependent manner. The Δ9-tetrahydrocannabinol- and cannabinol-treated cells had lower levels of phosphorylated protein kinase B [AKT (S473)], glycogen synthase kinase 3 alpha/beta, and endothelial nitric oxide synthase compared to the controls. The study of xenograft mice revealed that tumors treated with 15 mg/kg Δ9-tetrahydrocannabinol or 40 mg/kg cannabinol were significantly smaller than those of the control mice. The tumor progression rates in mice treated with 15 mg/kg Δ9-tetrahydrocannabinol or 40 mg/kg cannabinol were significantly slower than in the control group. Conclusions: These findings indicate that Δ9-tetrahydrocannabinol and cannabinol inhibit lung cancer cell growth by inhibiting AKT and its signaling pathways, which include glycogen synthase kinase 3 alpha/beta and endothelial nitric oxide synthase.

Hurricane-caused stormwater runoffs transport diverse terrestrial pollutants, adversely impact microbiological water quality, and introduce fecal and other pathogens to coastal water environments. This study investigated the genotypic diversity, phylogenetic composition, antibiotic resistance patterns, and virulence gene repertoire of the Enterococcus population in the Hilo Bay coastal water after the immediate impact of Hurricane Lane. DNA fingerprinting of Enterococcus isolates exhibited large genotypic diversity, while 16S rRNA gene sequencing identified four major species, including E. faecalis (34.7%), E. faecium (22.4%), E. hirae (22.4%), and E. durans (18.4%). Four common enterococcal virulence genes (cylA, esp, asa1, and gelE) were detected in the Enterococcus population, with significant portions of E. durans (33.3%), E. faecalis (41.2%), E. faecium (36.4%), and E. hirae (27.3%) isolates possessing two or more virulence genes. Considerable antibiotic resistance to rifampin, erythromycin, tetracycline, and nitrofurantoin was detected in the Enterococcus population, with one E. durans isolate showing vancomycin resistance. The results indicate considerable health implications associated with Enterococcus spp. in the hurricane-impacted tropical coastal water, illustrating the needs for more comprehensive understanding of the microbiological risks associated with storm-impacted coastal water. HIGHLIGHTS The study investigated the Enterococcus population in a tropical coastal water immediately after the impact of a major hurricane.; Genotypic diversity and phylogenetic composition of the Enterococcus population were determined.; A significant portion of the Enterococcus population contains various virulence factors.; Considerable antibiotic resistance was detected in the Enterococcus population.;

This paper proposes a preliminary study of making wax model from a customized FDM 3D- printer for jewelry application. Using external extrusion speed and heating control together with the XYZ gantry control of the original printer, two types of wax, injection grade and carving and milling wax were extruded through a plunger-cylinder extruder to form some basic shapes and Buddha statues. Flowability of waxes was investigated and the printing objects were observed. It was found that both waxes could be extruded at a temperature lower than their melting points. The modified FDM 3D-printer could produce 3D wax objects but the materials were easily spread outwards during printing. Further study focusing on printing parameters and material properties were required to improve the printing resolution and accuracy.

Abstract Background The ozonation of biofilters is known to alleviate clogging and pressure drop issues while maintaining removal performances in biofiltration systems treating gaseous volatile organic compounds (VOCs). The effects of ozone on the biofilter microbiome in terms of biodiversity, community structure, metabolic abilities, and dominant taxa correlated with performance remain largely unknown. Methods This study investigated two biofilters treating high-concentration toluene operating in parallel, with one acting as control and the other exposed to low-dosage (200 mg/m3) ozonation. The microbial community diversity, metabolic rates of different carbon sources, functional predictions, and microbial co-occurrence networks of both communities were examined. Results Consistently higher biodiversity of over 30% was observed in the microbiome after ozonation, with increased overall metabolic abilities for amino acids and carboxylic acids. The relative abundance of species with reported stress-tolerant and biofilm-forming abilities significantly increased, with a consortium of changes in predicted biological pathways, including shifts in degradation pathways of intermediate compounds, while the correlation of top ASVs and genus with performance indicators showed diversifications in microbiota responsible for toluene degradation. A co-occurrence network of the community showed a decrease in average path distance and average betweenness with ozonation. Conclusion Major degrading species highly correlated with performance shifted after ozonation. Increases in microbial biodiversity, coupled with improvements in metabolizing performances of multiple carbon sources including organic acids could explain the consistent performance commonly seen in the ozonation of biofilters despite the decrease in biomass, while avoiding acid buildup in long-term operation. The increased presence of stress-tolerant microbes in the microbiome coupled with the decentralization of the co-occurrence network suggest that ozonation could not only ameliorate clogging issues but also provide a microbiome more robust to loading shock seen in full-scale biofilters. Video abstract

Background Many countries now allow the consumption of cannabis or cannabinoids for medical purposes with varying approaches concerning products allowed and the regulatory frameworks prevailing their endowment. On 18 February 2019 Thailand passed legislation allowing the use of cannabis for medical purposes. This study aimed to examine patterns and purposes for consumption of medical cannabis, and consumers’ perceptions and opinions towards benefits and harms of cannabis and related policies in 2019–2020. Methods A cross-sectional study using a respondent-driven sampling (RDS) method was conducted in four sites across Thailand. Participants were 485 adults aged 18 years and over, living in the study region, who had used cannabis for medical purposes within the past 12 months. Face-to-face interviews using a structured questionnaire were used to collect data on (1) demographic characteristics, (2) pattern of consumption, (3) source of information and perception of benefits and harms of medical cannabis, and (4) opinion towards cannabis policies. Data were analyzed using RDS Analyst and presented as percentage and mean with 95% confidence interval (CI). Results Most participants (84.7%, 95% CI [78.9–90.5]) used an oral form of crude oil extract while 9.2% (95% CI [4.1–14.2]) used the raw form. The most common uses were for treatment of cancers (23.3%, 95% CI [16.1–30.4]), neuropsychiatric symptoms (22.8%, 95% CI [17.5–28.0]), and musculoskeletal pains (21.6%, 95% CI [16.7–26.6]). Illegal sources such as underground traders (54.5%, 95% CI [40.8–68.3]), friends and relatives (12.2%, 95% CI [6.2–18.3]), not-for-profit provider groups (5.2%, 95% CI [0.5–10.9]), and clandestine growers or producers (2.9%, 95% CI [0.6–5.3]) were the main suppliers. Most (>80%) perceived cannabis could treat cancers, chronic pains, insomnia, Parkinson’s disease and generalized anxiety disorder. Less than half perceived that cannabis could cause adverse conditions e.g., palpitation, panic, memory impairment and schizophrenic-like psychosis. Most respondents agreed or strongly agreed with the policies regarding permission to use cannabis for medical purposes (95.1%, 95% CI [92.0–98.2]), for the legal sale of medical cannabis products (95.9%, 95% CI [93.7–98.2]), and for people to grow cannabis for medical use (94.2%, 95% CI [91.8–96.5]). However, only two-thirds agreed with policies concerning the sales of cannabis (65.3%, 95% CI [56.9–73.7]) and home-grown cannabis for recreational purposes (61.3%, 95% CI [52.7–69.9]). Conclusion Our study reports the experiences of consumers of medical cannabis in the first year after its legalization in Thailand. Consumers reported various patterns and indications of consumption that were not supported by scientific evidence, but had positive perception of the results of consumption. These findings highlight ongoing policy challenges for Thailand and can be a lesson to be learned for other countries in the region.

Abstract Background High rates of dihydroartemisinin–piperaquine (DHA–PPQ) treatment failures have been documented for uncomplicated Plasmodium falciparum in Cambodia. The genetic markers plasmepsin 2 (pfpm2), exonuclease (pfexo) and chloroquine resistance transporter (pfcrt) genes are associated with PPQ resistance and are used for monitoring the prevalence of drug resistance and guiding malaria drug treatment policy. Methods To examine the relative contribution of each marker to PPQ resistance, in vitro culture and the PPQ survival assay were performed on seventeen P. falciparum isolates from northern Cambodia, and the presence of E415G-Exo and pfcrt mutations (T93S, H97Y, F145I, I218F, M343L, C350R, and G353V) as well as pfpm2 copy number polymorphisms were determined. Parasites were then cloned by limiting dilution and the cloned parasites were tested for drug susceptibility. Isobolographic analysis of several drug combinations for standard clones and newly cloned P. falciparum Cambodian isolates was also determined. Results The characterization of culture-adapted isolates revealed that the presence of novel pfcrt mutations (T93S, H97Y, F145I, and I218F) with E415G-Exo mutation can confer PPQ-resistance, in the absence of pfpm2 amplification. In vitro testing of PPQ resistant parasites demonstrated a bimodal dose–response, the existence of a swollen digestive vacuole phenotype, and an increased susceptibility to quinine, chloroquine, mefloquine and lumefantrine. To further characterize drug sensitivity, parental parasites were cloned in which a clonal line, 14-B5, was identified as sensitive to artemisinin and piperaquine, but resistant to chloroquine. Assessment of the clone against a panel of drug combinations revealed antagonistic activity for six different drug combinations. However, mefloquine-proguanil and atovaquone–proguanil combinations revealed synergistic antimalarial activity. Conclusions Surveillance for PPQ resistance in regions relying on DHA–PPQ as the first-line treatment is dependent on the monitoring of molecular markers of drug resistance. P. falciparum harbouring novel pfcrt mutations with E415G-exo mutations displayed PPQ resistant phenotype. The presence of pfpm2 amplification was not required to render parasites PPQ resistant suggesting that the increase in pfpm2 copy number alone is not the sole modulator of PPQ resistance. Genetic background of circulating field isolates appear to play a role in drug susceptibility and biological responses induced by drug combinations. The use of latest field isolates may be necessary for assessment of relevant drug combinations against P. falciparum strains and when down-selecting novel drug candidates.

Drinking, smoking, and health risk behaviors are significant problems for Thai adolescents. However, little is known about the association and magnitude among alcohol, tobacco, or co-using and health risk behaviors. Data of the National School Survey of 2007 were analyzed. The sample consisted of 50,033 high school and vocational college students. The interaction between gender and drinking-smoking status was significant for all health risk behaviors except for having sex and unprotected sex. Alcohol and tobacco had a stronger association with illegal substance use in boys than in girls. In contrast, their use had a stronger association with fighting, depression, and suicidal thoughts in girls than in boys. The intervention program for Thai youths in school should take into account the strong relationship between alcohol-tobacco consumption and these health risk behaviors. (Contains 3 tables.)

Objective: To investigate the effects of ∆9 -tetrahydrocannabinol, the principal psychoactive compound of Cannabis sativa, and cannabinol, a ∆9 -tetrahydrocannabinol degradative product, on human non-small cell lung cancer cells. Methods: ∆9 -Tetrahydrocannabinol and cannabinol were tested for anticancer activity in human non-small cell lung cancer (A549) cells. The effects on cell proliferation, apoptosis, and phosphorylation profiles were examined. The effects of ∆9 -tetrahydrocannabinol and cannabinol on tumor growth were also investigated using a xenograft nude mouse model. Apoptosis and targeted phosphorylation were verified by immunohistochemistry. Results: ∆9 -Tetrahydrocannabinol and cannabinol significantly inhibited cell proliferation and increased the number of apoptotic cells in a concentration-dependent manner. The ∆9 -tetrahydrocannabinol- and cannabinol-treated cells had lower levels of phosphorylated protein kinase B [AKT (S473)], glycogen synthase kinase 3 alpha/beta, and endothelial nitric oxide synthase compared to the controls. The study of xenograft mice revealed that tumors treated with 15 mg/kg ∆9 -tetrahydrocannabinol or 40 mg/kg cannabinol were significantly smaller than those of the control mice. The tumor progression rates in mice treated with 15 mg/kg ∆9 -tetrahydrocannabinol or 40 mg/kg cannabinol were significantly slower than in the control group. Conclusions: These findings indicate that ∆9 -tetrahydrocannabinol and cannabinol inhibit lung cancer cell growth by inhibiting AKT and its signaling pathways, which include glycogen synthase kinase 3 alpha/beta and endothelial nitric oxide synthase. [ABSTRACT FROM AUTHOR]

Abstract This research work investigates the axial stress versus strain responses of un-strengthened and carbon fiber reinforced polymer (CFRP) composites strengthened concrete specimens made with electronic waste coarse aggregates. For this purpose, 36 circular and non-circular 300 mm high concrete specimens constrained with CFRP sheets and partially replaced with E-waste coarse aggregates were prepared. The effect of cross-sectional geometry, 20% partial substitution of natural coarse aggregates with E-waste aggregates, corner effect of non-circular concrete specimens, confinement of specimens with CFRP sheets, and effect of the number of confinement sheets were also studied. In control concrete specimens, the coarse aggregates were 848 kg/m3 and E-waste aggregates were 212 kg/m3. The cement was 475 kg/m3 and fine aggregates were 655 kg/m3. Test results indicated that compressive strength is reduced by substituting natural coarse aggregates with E-waste aggregates. At the same time, compressive strength increased to 71%, 33%, and 25% for circular, square, and rectangular concrete specimens, respectively, by CFRP confinement. Whereas the axial strain increased to 1100%, 250%, and 133%, for circular, square, and rectangular concrete specimens, respectively, by CFRP confinement. CFRP sheets also enhanced the Poisson's ratio. Because of the greater confinement given by a double CFRP layer, it is more effective than a single layer. Furthermore, results also indicated that strength reduction in non-circular concrete specimens was greater than in circular concrete specimens for all studied cases. In the end, for theoretical calculations, strength and strain models for confined concrete suggested by different researchers were applied and compared with experimental results. In comparison to the experimental findings, theoretical data showed that most of the models were either on the higher or on the lower side, while only some model results matched well with the experimental data.

Abstract This study presents an experimental and finite element analysis of reinforced concrete beams with solid, hollow, prismatic, or non-prismatic sections. In the first part, a total of six beams were tested under four-point monotonic bending. The test matrix was designed to provide a comparison of structural behavior between prismatic solid and hollow section beams, prismatic solid and non-prismatic solid section beams, and prismatic hollow and non-prismatic hollow section beams. The intensity of shear was maximum in the case of prismatic section beams. The inclusion of a tapered section lowered the demand for shear. In the second part, Nonlinear Finite Element Modeling was performed by using ATENA. The adopted modeling strategy resulted in close agreement with experimental crack patterns at ultimate failure. However, the ultimate failure loads predicted by nonlinear modeling were generally higher than their corresponding experimental results. Whereas in the last part, the developed models were further extended to investigate the effect of the strength of concrete and ratio of longitudinal steel bars on the ultimate load-carrying capacity and cracking behavior of the reinforced concrete beams with solid, hollow, prismatic, or non-prismatic sections. The ultimate loads for each beam predicted by the model were found to be in close agreement with experimental results. Nonlinear modeling was further extended to assess the effects of concrete strength and longitudinal reinforcement ratio on failure patterns and ultimate loads. The parametric study involved beams reinforced with glass fiber-reinforced polymer (GFRP) bars against shear and flexural failure. In terms of ultimate load capacities, diagonal cracking, and flexural cracking, beams strengthened with GFRP bars demonstrated comparable performance to the beams strengthened with steel bars.

This research suggested natural hemp fiber-reinforced ropes (FRR) polymer usage to reinforce recycled aggregate square concrete columns that contain fired-clay solid brick aggregates in order to reduce the high costs associated with synthetic fiber-reinforced polymers (FRPs). A total of 24 square columns of concrete were fabricated to conduct this study. The samples were tested under a monotonic axial compression load. The variables of interest were the strength of unconfined concrete and the number of FRR layers. According to the results, the strengthened specimens demonstrated an increased compressive strength and ductility. Notably, the specimens with the smallest unconfined strength demonstrated the largest improvement in compressive strength and ductility. Particularly, the compressive strength and strain were enhanced by up to 181% and 564%, respectively. In order to predict the ultimate confined compressive stress and strain, this study investigated a number of analytical stress–strain models. A comparison of experimental and theoretical findings deduced that only a limited number of strength models resulted in close predictions, whereas an even larger scatter was observed for strain prediction. Machine learning was employed by using neural networks to predict the compressive strength. A dataset comprising 142 specimens strengthened with hemp FRP was extracted from the literature. The neural network was trained on the extracted dataset, and its performance was evaluated for the experimental results of this study, which demonstrated a close agreement.

This study presents an innovative approach to enhance the flexural capacity of cement-clay interlocking (CCI) brick walls using ferrocement jackets with an expanded wire mesh. The investigation involved 15 CCI brick walls subjected to flexural load testing, exploring various mesh sizes and anchor configurations on single and dual sides. The results revealed that while the primary failure mode involved dry joint opening and subsequent ferrocement debonding in the strengthened walls, effective anchorage mechanisms delayed dry joint opening until debonding occurred. The reinforced walls exhibited improved peak load capacity, notably in dual-sided reinforcement cases. With plastering on both sides and supplemented with anchors, an improvement of up to 221% in flexural capacity was obtained. The study emphasizes the influence of wire mesh size on anchorage effectiveness and its correlation with debonding susceptibility. Additionally, the moment-curvature analysis demonstrated resilient, ductile responses in load-bearing characteristics, with occasional abrupt declines due to ferrocement jacket debonding. Unlike control walls, the strengthened walls exhibited strains exceeding yield thresholds, indicating enhanced structural performance.

People who inject drugs (PWIDs) may engage in other behaviors with high risk of HIV transmission to various extents. However, data are scarce regarding differences in HIV testing and HIV positivity among PWIDs with and without high-risk behaviors. Such data can help inform stakeholders with regard to program prioritization. The objective of this study was to assess the extent that lifetime and past-year histories of HIV tests and HIV positivity varied by history of high-risk behaviors among PWIDs. We conducted a cross-sectional study with respondent-driven sampling (RDS) in the deep south provinces of Thailand during late 2019 thru early 2020. Data collection was done using structured questionnaire with face-to-face interviews. We analyzed data using descriptive statistics and multivariate logistic regression analyses. A total of 283 PWIDs gave verbal informed consent, and 282 PWIDs participated in the interview ( n = 282 PWIDs). Approximately 44.6% of the participants never had an HIV test. Participants with history of high-risk behaviors had significantly higher odds of lifetime HIV testing than participants with no history of high-risk behaviors (Adjusted OR = 2.94; 95% CI [1.11, 7.78]). Among participants with lifetime history of HIV tests, those with history of high-risk behaviors had significantly higher odds of being HIV-positive than those with no history of high-risk behaviors (Adjusted OR = 2.44; 95% CI [0.73, 8.17]). Stakeholders should consider encouraging those without history of high-risk behaviors not to be complacent about HIV testing, and ensure that those with high-risk behaviors have full access to HIV care when they test positive.

The utilization of recycled waste in the production of new concrete raises significant concerns regarding the quality of the resulting concrete. One prominent drawback of recycled aggregate concrete (RAC) is its inferior mechanical properties compared to natural aggregate concrete. In this study, we examine the impact of hemp fiber rope (HFR) confinement on improving the compressive stress-strain behavior of RAC, specifically using recycled brick aggregates from fired-clay solid bricks (RAC-FCSB) as a partial substitute for natural coarse aggregates. Furthermore, we explore and compare the effectiveness of HFR confinement in the form of strips versus fully wrapped confinement. To conduct the experiments, a comprehensive framework was developed, involving a total of 32 cylindrical specimens. The parameters of interest included the configuration of HFR confinement (strips or full wrapping), the number of HFR layers, and the inherent strength of the concrete. The results indicate that HFR strips can significantly enhance the compressive stress-strain response. However, their performance falls short when compared to the fully wrapped HFR confinement. Nonetheless, HFR strips were able to enhance the peak compressive stress and strain of RAC-FCSB up to 204% and 190%, respectively. The second part of the study investigated the performance of existing models of HFR confinement in predicting the peak compressive stress and strain of RAC-FCSB. The deficiencies in existing models were highlighted, and new models based on non-linear regression analysis were proposed to accurately predict the peak compressive stress and strain of HFR-confined RAC-FCSB.

Each year, an enormous amount of construction waste is produced worldwide. The reuse of construction waste in construction works is a sustainable solution. The present research work utilized recycled brick aggregates in the production of concrete. The resulting concrete exhibited substandard splitting tensile, flexural, and compressive properties. Steel fibers were used to improve these substandard properties of recycled brick aggregate concrete. The volume fractions of 1%, 2%, and 3% for steel fibers were mixed in concrete, whereas recycled brick aggregates were obtained from solid fired-clay bricks, hollow fired-clay bricks, and cement–clay interlocking bricks. The compressive strength was enhanced by up to 35.53% and 66.67% for natural and recycled brick aggregate concrete, respectively. Strengthened flexural specimens demonstrated up to 8765.69% increase in the energy dissipation. Specimens strengthened with steel fibers showed substantially improved splitting tensile, flexural, and compressive responses. Separate equations were proposed to predict the peak compressive strength, strain at peak compressive strength, elastic modulus, and post-peak modulus of recycled brick aggregate concrete. The proposed regression equations were utilized in combination with an existing compressive stress–strain model. A close agreement was observed between experimental and predicted compressive stress–strain curves of recycled brick aggregate concrete.

The transition toward sustainable transportation includes adopting ecofriendly electric vehicles in public transport, which reduces greenhouse gas emissions and increases energy efficiency. One of the critical features in fuel economy improvement of electric vehicles lies in lightweight structural design. Nevertheless, the crashworthiness of the structures of the vehicles and the safety of passengers must be guaranteed in the attempt of mass reduction because the crash of large vehicles such as buses usually costs many lives. This paper, therefore, aims to present an in-depth analysis of the impact behavior of a lightweight monocoque sandwich composite microbus body under full-frontal crash conditions. The bus structure, made of a high-density polyurethane foam core and woven glass fabric-epoxy face sheets, was modeled and simulated via LS-DYNA dynamic analysis using strength-based Chang-Chang criteria to characterize the failure mechanism of the structure and investigate intrusion into the passenger survival space. Under front collision, the front panel, A-pillars, and front sidewalls of the original bus were found to be extensively damaged in the compressive fiber mode. Based on the 50th percentile male dummy anthropometric parameters, injury indices of 0-5 intervals were proposed to evaluate occupant injury risks. The maximum front and side intrusion into the specified safety space under a maximum impact speed of 50 km/h is 208 mm at the front panel and 221 mm at the sidewall, indicating high injury indices of 3.59 and 4.81, respectively. The effects of stiffeners reinforced in the front panel and foam core thicknesses in the sidewalls, floor, and bottom parts on crashworthiness improvement were thoroughly discussed. The improved bus design can significantly enhance the safety of the occupants with a minimal increase in structural weight of merely 35.6 kg. An effective vehicle safety design under full frontal collision is presented.

This study investigated the influence of CFRP composite wrapping techniques on the load–deflection and strain relationships of non-prismatic RC beams. A total of twelve non-prismatic beams with and without openings were tested in the present study. The length of the non-prismatic section was also varied to assess the effect on the behavior and load capacity of non-prismatic beams. The strengthening of beams was performed by using carbon fiber-reinforced polymer (CFRP) composites in the form of individual strips or full wraps. The linear variable differential transducers and strain gauges were installed at the steel bars to observe the load–deflection and strain responses of non-prismatic RC beams, respectively. The cracking behavior of unstrengthened beams was accompanied by excessive flexural and shear cracks. The influence of CFRP strips and full wraps was primarily observed in solid section beams without shear cracks, resulting in enhanced performance. In contrast, hollow section strengthened beams exhibited minor shear cracks alongside the primary flexural cracks within the constant moment region. The absence of shear cracks was reflected in the load–deflection curves of strengthened beams, which demonstrated a ductile behavior. The strengthened beams demonstrated 40% to 70% higher peak loads than control beams, whereas the ultimate deflection was increased up to 524.87% compared to that of the control beams. The improvement in the peak load was more prominent as the length of the non-prismatic section increased. A better improvement in ductility was achieved for the case of CFRP strips in the case of short non-prismatic lengths, whereas the efficiency of CFRP strips was reduced as the length of the non-prismatic section increased. Moreover, the load–strain capacity of CFRP-strengthened non-prismatic RC beams was higher than the control beams.

This study investigated the grouted sleeve splices and corrugated duct splices between shear walls and footing. In this regard, three shear walls were experimentally tested. One wall was cast monolithically with the foundation (RCWS), whereas two walls were precast. One wall was connected to the foundation using splice sleeves (PGWS), and another with corrugated duct splices (PCWS). All the walls were tested under reverse cyclic loading and a constant axial load. It was observed that the performance of specimen PGWS was controlled by rocking, and a premature connection loss was observed at one of the grouted sleeve splices. The hysteretic performance of specimen PCWS was close to that of specimen RCWS, whereas extensive pinching was observed in the hysteretic response of specimen PGWS. The peak load, ductility, secant stiffness, and energy dissipation of specimens RCWS and PCWS were in good agreement, whereas the energy dissipated by specimen PGWS was considerably lower than the corresponding values of specimens RCWS and PCWS. Nonlinear fiber-based modeling in OpenSees was performed using SFI-MVLEM elements. The predicted hysteretic response of the OpenSees model was in close agreement with the experimental response.

Many masonry structures are constructed with cement clay interlocking brick (CCIB) due to its added benefits. Recent research has demonstrated the vulnerability of brick masonry walls against seismic loading. Various strengthening materials and techniques are extensively used to improve the structural behavior of brick walls. Carbon fiber-reinforced polymer (CFRP) composites are the most popular strengthening material due to their advantages of easy application, lightweight qualities, and superior tensile strength. The current research work aimed to explore the cost-effective solutions and feasibility of CFRP composite-based strengthening techniques to improve the load-bearing capacity of CCIB walls. Various configurations and combinations of strengthening materials were investigated to customize the cost of repair and strengthening. The experimental results indicated that CFRP composites in combination with cement-sand (CS) mortar are an efficient strengthening material to enhance the strength and ultimate deflection of CCIB walls. The ultimate load-bearing capacity and axial deformation of the strengthened CCIB wall (using two layers of CFRP strips and CS mortar of 10 mm thickness) remained 171% and 190% larger than the unstrengthened CCIB wall. The conclusions of this study are expected to enhance the seismic performance of masonry buildings in developing countries. It should be noted that due to the reduced number of tested specimens, the results to be assumed as general considerations need a wider experimental campaign and a large numbers of tests for each strengthening typology.