Loading Tests Research Articles

To Monitor Fracture Behaviors in Four-Point Cyclic Bending Tests of Low-Activated High Alumina Concrete and Standard Concrete RC Beams Using Acoustic Emission Technique

In this study, acoustic emission monitory (AE) was used to observe and evaluate the mechanical behavior of two kinds of RC beam members, made of low-activation concrete and normal concrete, by general four-point bending test and cyclic four-point bending test. During the loading, acoustic emissions due to cracking, shearing, rubbing, de-bonding or interlocking could be monitored and recorded using a real-time high sampling rate DAQ system and proper sensors; besides, beam displacement, cracking situation and loading were also measured simultaneously. The experiment goals included: (1) to observe the damage mechanisms of the beams under bending test and their corresponding AE performance; and (2) to observe the material fracture and corresponding AE in the beams under the cyclic bending test of 0.5Hz (periodic dynamic condition). After experiments, the fracture history of the beam under general loading test could be revealed through the comparison for the chronicled AE signal density and load/strain data. The damage on beam under the cyclic test could be analysed through the chronological comparison for the cumulative sum of AE signal counts obtained for different test periods and stages. Both the irreversibility on fracture mechanism (affected by the Kaiser effect) and the “remainder toughness” could be discussed through the quantitative analysis on AE characteristics for two different beams. They might relate to the durability and toughness of material for beam.

A Study on the Time-Frequency Characteristics of Electromagnetic Radiation Signals during Concrete Cracking

At the moment of rupture, brittle materials such as concrete, coal, and rocks experience a sudden stress change that generates oscillating positive and negative charges on the crack surfaces, resulting in the emission of electromagnetic radiation (EMR) signals. While extensive investigations have focused on the EMR signals produced during the fracturing of coal and rocks, limited attention has been given to the signals arising from concrete cracking. Previous studies have predominantly concentrated on amplitude or frequency domain analysis, lacking a comprehensive exploration of the time-frequency domain characteristics of electromagnetic signals. In this study, various magnetic field sensors capable of collecting frequencies ranging from 50Hz to 50kHz are developed. A laboratory testing platform for concrete cracking is established with the utilization of data acquisition equipment and a rock point load tester. The EMR signals are subjected to time-frequency domain analysis using Short-Time Fourier Transform (STFT) methods. The study explores the relationship between the time-frequency domain characteristics of EMR signals and concrete dimensions, as well as the instantaneous stress drop at the moment of fracture. Experimental findings reveal that the dominant frequency of EMR signals generated during concrete cracking is in the low-frequency range. As the instantaneous stress drop at the moment of fracture increases, the frequency of the EMR signals shifts towards higher frequencies and the signals around 10kHz has a longer duration. When the frequency of EMR signals is lower than 20kHz, larger concrete dimensions result in greater stress drops at the moment of fracture, leading to higher intensity EMR signals. Utilizing the EMR characteristics of concrete cracking holds promise for monitoring the safety and stability of concrete structures.

Evaluating of 14H-Piles’ Load Capacity in Cohesionless Soils for Edward’s Project Using ?-Method and Finite Element Method

Abstract: This paper presents a comprehensive study on evaluating the load capacity of 14H-piles in cohesionless soils for Edward's infrastructure project[1]. The project, overseen by the Federal Highway Administration (FHWA) and the Colorado Department of Transportation (CDOT), focuses on bridge replacements in Edwards, Colorado, with an emphasis on foundation improvements using driven pile foundations[2]. The research utilizes Finite Element Analysis (FEA) and the β-method to assess the total bearing capacity of 14H-piles in sandy soil conditions[3]. Field exploration, including Standard Penetration Tests (SPT), is conducted to determine soil parameters, followed by calibration of soil strength parameters. The study involves modelling the piles using the Soil-Structure Interaction 3-D program (SSI3D) and comparing the total bearing capacity obtained from FEA with nominal capacities calculated by the β-method. Additionally, the paper discusses load resistance and factor design, as well as the importance of static load testing for validation[4]. The results highlight the efficacy of FEA in predicting pile behaviour and provide valuable insights for foundation design in similar geological settings.

Investigation of Ferrocement Plate Affected by Flexural Filling up

Abstract: In spite of the fact that terrorist attacks are exceptional instances caused by human dynamic loads, such as blast loads, which must be carefully calculated like wind and seismic loads, the increased number of terrorist attacks in the last few years has largely shown that the impact of blast loads on structures is a real concern that we should take into account during the configuration procedure of structures. This article also introduces the behavior of ferrocement composites under blast loading, which are used as long-lasting formwork in traditional reinforced concrete constructions. Specimens of single ferro cement panels are subjected to blast load testing both analytically and experimentally, and the behavior of load deflection is then examined.

Seismic cyclic test of perforated replaceable link for eccentrically braced frames

This study introduces a design comprising a unweakened link and four variants of perforated replaceable links, denoted as specimens RX1 (unweakened link), RX2 and RX3 (with circular holes of 50mm diameter on the web), RX4 and RX5 specimens (with elliptical holes on the web), and RX6 and RX7 specimens (with weakened flanges and circular holes of 50mm and 80mm diameter on the web). Seven link specimens underwent cyclic loading tests. RX1 ultimately failed due to tearing of the weld at the connection between the flange and the end plate, while RX2 to RX7 exhibited deformation concentrated within the energy dissipating region, ceasing loading upon failure of this region, demonstrating enhanced safety and stability. All specimens exhibited relatively full hysteretic curves, with a decrease in the area of hysteretic curves corresponding to an increase in the web perforation ratio. The overstrength coefficient for specimen RX1 ranged from 1.81 to 1.82, while for specimens RX2 to RX7, it ranged from 1.80 to 3.65. Not only were the overstrength coefficients greater than RX1, but also the cumulative energy dissipation was higher than RX1. This indicates that RX2 to RX7 can accommodate larger plastic deformations, effectively utilizing plastic deformation for energy dissipation, thereby exhibiting superior safety. Moreover, an increase in web perforation ratio and weakening of the flanges resulted in a decrease in the overstrength coefficient, load-bearing capacity, and plastic deformation capacity of the specimens. Ductility decreased with increasing web perforation ratio but increased with flange weakening. Additionally, through analysis of link replacement time and residual rotation of links after unloading, it was observed that perforated replaceable links exhibited favorable replaceability.

Self-centering concrete-filled steel tubular column-steel beam joint: Experiment and numerical modeling

This paper studied the seismic behavior of a novel self-centering concrete-filled steel tubular column-steel beam (SCSTCSB) joint. The restoring force was provided by the post-tensioned tendons arranged in the CFST columns. Cyclic loading tests were performed on five 1/3 scaled specimens by varying the parameters of steel tendon type, concrete strength (fc), and axial compression ratio (n). The failure modes, hysteresis behavior, stiffness and strength degradation, energy dissipation, post-tensioned tendons response, residual deformation, and strain distribution were studied in detail. The finite element models were established to capture the stress distribution of the joints. In addition, parameter analysis was performed by expanding 17 finite element models. The results show that the ratio of residual deformation to beam rotation angle of the specimens ranged from 0.068 to 0.172. And the proposed joints demonstrated excellent self-centering ability. The self-centering (SC) performance of joints with ordinary steel tendons was better than that of joints with high-strength steel tendons. With the increase of n, the SC performance of the joints intensified at the lower ratio (n from 0.1 to 0.3) and weakened after n = 0.3. The flexural capacity of the joints improved with the increase of axial compression ratio (n), width-thickness ratio (D/t), diameter of steel tendons (d), and assembly part strength (fy,a).

Biomechanical Comparison of Fixation Methods for Posterior Wall Fractures of the Acetabulum: Conventional Reconstruction Plate vs. Spring Plate vs. Variable Angle Locking Compression Plate

Background and Objectives: Acetabular fractures, though infrequent, present considerable challenges in treatment due to their association with high-energy trauma and poor prognoses. Posterior wall fractures, the most common type among them, typically have a more favorable prognosis compared to other types. Anatomical reduction and stable fixation of the posterior wall are crucial for optimal treatment outcomes. This study aimed to biomechanically compare three commonly used fixation methods for posterior wall fractures of the acetabulum—a conventional reconstruction plate, a spring plate, and a 2.7 mm variable angle locking compression plate (VA-LCP). Materials and Methods: The study utilized 6 fresh-frozen cadavers, yielding 12 hemipelvises free from prior trauma or surgery. Three fixation methods were compared using a simple acetabulum posterior wall fracture model. Fixation was performed by an orthopedic specialist, with prebending of plates to minimize errors. Hemipelvises were subjected to quasi-static and cyclic loading tests, measuring fracture gap, stiffness, and displacement under load. Results: It showed no significant differences in fracture gap among the three fixation methods under cyclic loading conditions simulating walking. However, the conventional reconstruction plate exhibited a greater stiffness compared to the spring and variable angle plates. Fatigue analysis revealed no significant differences among the plates, indicating a similar stability throughout cyclic loading. Despite differences in stiffness, all three fixation methods demonstrated adequate stability under loading conditions. Conclusions: While the conventional reconstruction plate demonstrated a superior stiffness, all three fixation methods provided sufficient stability under cyclic loading conditions similar to walking. This suggests that postoperative limitations are unlikely with any of the three methods, provided excessive activities are avoided. Furthermore, the variable angle plate—like the spring plate—offers an appropriate stability for fragment-specific fixation, supporting its use in surgical applications. These findings contribute to understanding the biomechanical performance of different fixation methods for acetabular fractures, facilitating improved surgical outcomes in challenging cases.

Seismic behavior of plate‐reinforced composite coupling beams with steel bar truss deck

SummaryTo better meet the evolving requirements of industrialized building system, this paper introduces a novel approach by proposing the utilization of a plate‐reinforced composite (PRC) coupling beam, which incorporates a steel bar truss deck as a substitute for the conventional reinforced concrete (RC) slab. In order to study the effect of different types of RC slabs on the performance of PRC coupling beams, the low‐cyclic reversed loading test was carried out on three PRC coupling beams. The differences of failure modes, load bearing capacity, stiffness degradation, and energy dissipation capacity of each coupling beam are analyzed. The finite element software ABAQUS is used to analyze the stress distribution in the concrete, steel plate, and reinforcement skeleton of the novel coupling beam. The results show that the incorporation of a steel bar truss deck in PRC coupling beams with a small span‐to‐depth ratio can effectively enhance their shear bearing capacity and energy dissipation capacity. The inclusion of a slab significantly enhances the load‐bearing capacity of the coupling beam, while the utilization of a steel bar truss deck in PRC coupling beams greatly improves their overall bearing capacity. The PRC coupling beams featuring a steel bar truss deck exhibit superior load capacity compared to those with conventional RC slabs. The cumulative energy dissipation at the damage point in PRC beams with a steel bar truss deck is 1.39 times greater than that of the coupling beam without slabs and 1.18 times higher than that of the coupling beam with traditional RC slabs.

Static and dynamic responses of buried steel pipe under truck load: An experimental study

The behavior of a buried pipe under static and dynamic loading conditions has been investigated through full-scale field tests. A plain steel pipe with a diameter of 762 mm was gauged at the outer surface of two pipe sections. A dump truck was employed for the static and dynamic loading tests. Under static loading, the measured pipe strains increase with increasing axle load and decreasing cover depth. The measured strains under dynamic loading show three peaks, which correspond to the times at which the front, middle, and rear axles, respectively, reach the pipe centerline. The offset loading pattern produces greater strains than the non-offset one while keeping the axle load constant under both static and dynamic loads. It is discovered that the pipe strains caused by each truck axle vary with truck speed. Since the load transfer is influenced by a number of factors, including the truck load, road roughness, truck speed, and others, a moving truck load does not always result in higher pipe strains as compared to a static load. The complexity of dynamic pipe responses can be explained in part by a single-degree-of-freedom (SDOF) model.

Measurement Refinements of Ground-Based Radar Interferometry in Bridge Load Test Monitoring: Comprehensive Analysis on a Multi-Span Cable-Stayed Bridge

This paper presents three refinements in ground-based radar interferometer (GB-radar) measurement for bridge load testing: (1) GB-radar phase jumps were detected for the first time on bridge tower displacement monitoring, and a recovery method is presented to obtain the correct unwrapped value; (2) a precise displacement projection method considering target deformation was exploited, and a case study of the Fifth Nanjing Yangtze River Bridge (FNYRB) GB-radar campaign shows that a centimeter-level compensation can be achieved; (3) a post-construction settlement phenomenon was found during the FNYRB static load tests, characterized by 0.31 mm/min, which accumulated up to 25 mm. In addition, the dynamic monitoring capabilities of GB-radar for the bridge tower and girder were verified, highlighting its potential for bridge structural health monitoring (SHM). The insights gained from this study offer valuable recommendations for future GB-radar bridge displacement monitoring.

Experimental Investigation on Mechanical, Electrical, and Fatigue Properties of Entangled Metal Wires under Cyclic Dynamic Load Test

Experimental Investigation on Mechanical, Electrical, and Fatigue Properties of Entangled Metal Wires under Cyclic Dynamic Load Test

Risk of Neonatal Hypoglycemia in Infants of Mothers With Gestational Glucose Intolerance.

To examine the relationship between gestational glucose intolerance (GGI) and neonatal hypoglycemia. This was a secondary analysis of 8,262 mother-infant dyads, with delivery at two hospitals between 2014 and 2023. We categorized maternal glycemic status as normal glucose tolerance (NGT), GGI, or gestational diabetes mellitus (GDM). We defined NGT according to a normal glucose load test result, GGI according to an abnormal glucose load test result with zero (GGI-0) or one (GGI-1) abnormal value on the 100-g oral glucose tolerance test, and GDM according to an abnormal glucose load test result with two or more abnormal values on the glucose tolerance test. Neonatal hypoglycemia was defined according to blood glucose <45 mg/dL or ICD-9 or ICD-10 diagnosis of neonatal hypoglycemia. We used logistic regression analysis to determine associations between maternal glucose tolerance category and neonatal hypoglycemia and conducted a sensitivity analysis using Δ-adjusted multiple imputation, assuming for unscreened infants a rate of neonatal hypoglycemia as high as 33%. Of infants, 12% had neonatal hypoglycemia. In adjusted models, infants born to mothers with GGI-0 had 1.28 (95% 1.12, 1.65), GGI-1 1.58 (95% CI 1.11, 2.25), and GDM 4.90 (95% CI 3.81, 6.29) times higher odds of neonatal hypoglycemia in comparison with infants born to mothers with NGT. Associations in sensitivity analyses were consistent with the primary analysis. GGI is associated with increased risk of neonatal hypoglycemia. Future research should include examination of these associations in a cohort with more complete neonatal blood glucose ascertainment and determination of the clinical significance of these findings on long-term child health.

High-Impact Dynamic Loading Method for Calibration of Triaxial Acceleration Sensors

Abstract In this study, a high-impact dynamic loading device was designed to generate a three-dimensional pulse excitation signal with high intensity shock acceleration and achieve triaxial synchronous calibration of a triaxial acceleration sensor. A light-gas gun interior ballistic model and a sensor mechanical response model were developed, and the relationships between the bullet impact velocity, barrel length, and initial chamber pressure were obtained. Additionally, the transformation relationship of the sensor’s triaxial acceleration in different coordinate systems was derived. Based on the stress wave theory and the finite element method, the influence of the bullet impact velocity on the variation pulse, and different slope and deflection angles on the triaxial acceleration were analyzed. By optimizing the parameter design, machining the prototype, and conducting high-impact dynamic loading tests, the results showed that the deviation between theoretical and measured values of the generated triaxial acceleration signal was small, and the maximum deviation was less than 4%. This indicated that the proposed high-impact dynamic loading device satisfied the calibration requirements for calibrating triaxial acceleration sensors, which can generate a three-dimensional acceleration with a peak value of not less than 700,000 m/s².

Uncovering the progressive failure process of primary coal-rock mass specimens: Insights from energy evolution, acoustic emission crack patterns, and visual characterization

The failure and instability of deep coal-rock mass structures, which are influenced by mining disturbances, are major contributors to disasters like rock bursts. This study involved conducting indoor experiments using uniaxial loading test and acoustic emission (AE) experiments on indigenous primary coal-rock mass (PCRM). We utilize chaotic bifurcation based on strain energy to characterize the progressive damage stages of PCRM, demonstrating the chaotic characteristics of energy evolution during the gradual destruction process. The degree of damage resulting from PCRM failure was evaluated by jointly applying P-wave velocity tomography and AE event localization. Additionally, the classification of crack patterns in PCRM was conducted using the RA-AF correlation analysis method. The segmentation boundaries of crack classification patterns were then redefined using the Gaussian mixture model (GMM) algorithm. The research findings indicate that the chaotic bifurcation model of strain energy classifies stress into four stages: the stable region (Ⅰ), the metastable region (Ⅱ), the bifurcation region (Ⅲ), and the chaotic region (Ⅳ). The presence of a low-velocity zone in P-waves may indicate crack accumulation and damage within the system. Additionally, areas with abnormal P-wave velocities exhibit numerous AE events. The crack classification patterns of the four stages undergo an evolution from predominantly tensile cracks to a mixture of tensile and shear cracks, and the GMM algorithm successfully identifies the optimal separation path for crack classification boundaries. We propose an adaptive kernel density estimation (AKDE) algorithm to quantify the spatial distribution of AE events, thus offering a visual representation of the damage patterns at various stages.

#1096 Improving the diagnostic accuracy of absorptive hypercalciuria: a comparative analysis of calcium load tests at 2-hour and 4-hour intervals

Abstract Background and Aims A calcium load test (CLT) has been developed by Pak et al in 1974 to better discriminate absorptive, resorptive and renal hypercalciuria, leading to a tailored treatment approaches for patients. Originally, Calcium load was a 4-hours (4 h) test with a timepoint at 2-hours (2 h) defining an absorptive hypercalciuria (AH) by an increase of the difference between urinary calcium on creatininuria ratio (ΔUCa/Cr) of more than 0.5 mmol/mmol. In clinical practice and in more recent studies, CLT is only a 2 h test using this 0.5 or sometime 0.6 mmol/mmol cut-off. We hypothesized that a 2-hours timepoint is not sufficient to diagnose all AH and that the 4-hours timepoint as initially described is more efficient to improve accuracy of AH diagnosis. Method We report a single-centre, retrospective study including all patients who underwent CLT between January 2015 and September 2020. These tests were carried out in patients with hypercalciuria or in patients with elevated parathyroid hormone (PTH, standard 15-65 ng/L, Elecsys PTH) with normocalcemia, with or without kidney stones history. After a low-calcium diet for 3 days and a 12-hours fast, 24-hours urine were collected and blood and urinary samples were done at arrival. Two hours and 4 h after ingestion of one gram of calcium per os, blood and urinary samples were collected. AH was diagnosed by a ΔUCa/Cr at baseline and 2 h or 4 h timepoints of more than 0.5 mmol/mmol. We compared the number of AH diagnosed after 2 h and 4 h of testing using a 0.5 mmol/mmol delta at each timepoint. We also analysed clinical and biological profile of early and late AH. Results A total of 328 patients were included, 48 ± 14.8 years old, mean glomerular filtration rate of 92.8 ± 22.1 mL/min/1.73 m², 52.8% of women. At baseline, ionized calcemia (iCa2+) was 1.2 ± 0.1 mmol/L with a significant increase at 2 h (1.3 ± 0.1 mmol/L, p &amp;lt; 0.001) and a stabilisation at 4 h (1.3 ± 0.1 mmol/L, p = ns). Simultaneously, PTH showed a significant drop between baseline and 2-hours (60 ± 26.1 ng/L versus 35.3 ± 19.7 ng/L, p &amp;lt; 0.001) follows by a significant increase between 2 and 4 h (35.3 ± 19.7 ng/L versus 39.5 ± 21.4 ng/L, p &amp;lt; 0.01). Mean 25-Hydroxyvitamin D and 1,25-Dihydroxyvitamin D3 were respectively 67.4 ± 24.7 ng/mL and 154.6 ± 54pg/mL. Baseline UCa/Cr ratio was 0.3 ± 0.2 mmol/mmol and increased significantly after 2 h (0.6 ± 0.3 mmol/mmol, p &amp;lt; 0.001) and 4 h (0.8 ± 0.4 mmol/mmol, p &amp;lt; 0.001) (Fig. 1a). ΔUCa/Cr was significantly different between baseline and 2 h and between baseline and 4 h (0.2 ± 0.2 versus 0.5 ± 0.4, p &amp;lt; 0.001) (Fig. 1b). AH was diagnosed in 35 (10.7%) patients after 2 h, 84 (25.6%) more were diagnosed at 4 h (p &amp;lt; 0.001) for a total of 119 (36.3%) AH diagnosed. Between early and late AH, we found no significant differences in 1,25-Dihydroxyvitamin D3, phosphatemia or phosphaturia, but 25-Hydroxyvitamin D which (67.3 ± 21 ng/mL in late AH versus 59.2 ± 18.3 ng/mL, p = 0.039). In comparison to the rest of the cohort, AH have a higher 1,25-Dihydroxyvitamin D3 level, a lower PTH at 2 h and 4 h, a lower phosphaturia at 2 h and 4 h and a higher magnesiuria at 4 h. Conclusion This study shows that performing the 4 h CLT improves the diagnosis of AH with more than fifty percent of AH diagnosed within 4 h of calcium ingestion. It seems that there are AH of later diagnosis with a similar clinical and biological profile depending of enteral absorption.

#1405 Salt sensitivity and hypertensive nephropathy: a link to be discovered

Abstract Background and Aims Sodium sensitivity (SS) is a change in blood pressure (BP) depending on Na+ intake, 30% of population has it. Either a salt load test or a sodium dietary protocol can be used to stratify the population into 3 groups based on BP variation: sodium sensitive (SS), sodium resistant (SR), inverse sodium sensitivity (ISS), based on an increase, a non-significant variation or a decrease in BP following the administration of Na+. SNPs located in genes related with Na+ metabolism, aldosterone synthesis and kidney tubular Na+ reabsorption are related to this phenotype. Method We analyzed data collected from the follow-up (FUP) of 127 subjects with a new diagnosis of hypertension, categorized by their profile through acute salt load test. We analyzed the kidney damage by annual decline of eGFR and development of microalbuminuria. Genetic polymorphism analysis has been executed. Results No differences in the decline of eGFR are observed among the groups (−1.3084 ml/min ± 0.16 p-Value 0.372). SR subjects seem to be more prone to develop earlier microalbuminuria (χ 2 10.682, p = 0.005) even with an adequate BP control (P-Anova SBP 0.766; P-Anova DBP 0.856). An inverse correlation exists between pressure-natriuresis ratio and decline in eGFR (R −0.194 p = 0.016). Polymorphism in CYP11B2 (0.72 OR p = 0.045) and NEDD4L (0.74 OR p = 0.027) are protective against eGFR decline. ADD3 polymorphism (3.73 OR p = 0.049) is a risk factor for development of microalbuminuria. KL (0.15 OR p = 0.034), PKD and TRPC6 (p-Value 0.037, p-Value 0.009) polymorphism are protective factor against microalbuminuria. Conclusion SR patients are more at risk of developing hypertensive nephropathy earlier than other groups; steeper pressure natriuresis ratio is involved in quicker decline in renal function possibly accelerating development of hypertensive nephropathy. Further studies with larger sample and standardization in salt sensitivity test are needed to translate this knowledges into clinical setting.

Mechanical Characteristics of Cracked Lining Reinforced with Steel Plate–UHPC Subjected to Vertical Load

The steel plate reinforcement method is widely used for strengthening damaged linings. Nevertheless, low durability is one of the disadvantages of the steel plate reinforcement method, which uses epoxy resin as the interface binder. To enhance the load-bearing performance and strengthening effect of steel-plate-reinforced structures, this study introduced ultra-high performance concrete (UHPC) as the reinforcing bonding layer and proposed a novel method for steel plate–UHPC reinforcement of cracked linings. A mechanical performance model test was conducted on a 1/5 scale lining model using a loading test device to evaluate the load-bearing performance and stress deformation of both conventional steel plate and steel plate–UHPC reinforced cracked linings. The characteristics, mechanisms of failure, and impacts of strengthening of the steel plate reinforcement method and steel plate–UHPC reinforcement method for cracked linings were compared. A numerical simulation model was developed to investigate the reinforcement effect of cracked linings using steel plate–UHPC reinforcement. The analysis included examining the influence of steel plate thickness, UHPC bonding layer thickness, and reinforcement timing. Model test results show that the overall damage mode of the steel plate–UHPC-reinforced structure had good elastic–plastic behaviour, and the deformation and damage process under the vertical concentrated load can be divided into four typical phases. Compared with the traditional steel plate reinforcement, the ultimate load-carrying capacity and ductility of the steel plate–UHPC-reinforced structure were increased by 53% and 366%, respectively, showing significantly better load-carrying capacity and deformation performance. Numerical simulation results show that the reinforced structure’s load-carrying capacity and stiffness enhancement rate increased non-linearly with the increase in UHPC layer thickness and steel plate thickness. However, reasonable reinforcement timing exists for steel plate-UHPC reinforcement, and too late reinforcement timing leads to a decrease in structural load-carrying capacity and stiffness enhancement rate.

Predictors of HIV Viral Load Suppression After Enhanced Adherence Counseling, Nekemte, Ethiopia.

Enhanced adherence counseling refers to the counseling intervention for Human Immunodeficiency Virus (HIV) patients with an elevated viral load result, a viral load of > 1000 copies/ml, on a routine or need-based viral load test. The Federal Ministry of Health, Ethiopia, has launched routine viral load testing and enhanced adherence counseling since 2016 for high-viral load people living with HIV, which is applicable throughout the country for all health facilities providing HIV care and treatment. Our study aimed to assess viral load suppression after enhanced adherence counseling and its predictors among high viral load people living with HIV who were on antiretroviral therapy. We conducted a health facility-based retrospective follow-up study among 352 HIV-infected high-viral load people enrolled in enhanced adherence counseling from July 2018 to June 2021 in Nekemte town public health facilities. Cox proportional hazard analysis was used to identify independent predictors. The overall 65.1% of 352 persons on antiretroviral treatment achieved HIV viral load suppression after enhanced adherence counseling, (15.01 per 100 person months (95% CI13.02-16.99)). The median time to viral load suppression was 5 months. Age ≥ 15 years (AHR = 1.99, 95% CI: 1.11-3.57), no history of opportunistic infection (AHR = 2.01, 95% CI: 1.18-3.41), and not using substances (AHR = 2.48, 95% CI: 1.19-5.14) were more likely to have viral load suppressed, while having an initial viral load count greater than 50,000 RNA copies/ml (AHR = 0.56, 95% CI: 0.37-0.85) were less likely to have viral load suppressed after enhanced adherence counseling. Age, history of opportunistic infections, substance use, and an initial viral load count > 50,000 RNA copies/mL were significant predictors of viral load suppression. Enrolling all high-viral-load patients in enhanced adherence counseling is recommended for viral load suppression.

Composite patch with negative Poisson's ratio mimicking cardiac mechanical properties: Design, experiment and simulation

Developing patches that effectively merge intrinsic deformation characteristics of cardiac with superior tunable mechanical properties remains a crucial biomedical pursuit. Currently used traditional block-shaped or mesh patches, typically incorporating a positive Poisson's ratio, often fall short of matching the deformation characteristics of cardiac tissue satisfactorily, thus often diminishing their repairing capability. By introducing auxeticity into the cardiac patches, this study is trying to present a beneficial approach to address these shortcomings of the traditional patches. The patches, featuring the auxetic effect, offer unparalleled conformity to the cardiac complex mechanical challenges. Initially, scaffolds demonstrating the auxetic effect were designed by merging chiral rotation and concave angle units, followed by integrating scaffolds with a composite hydrogel through thermally triggering, ensuring excellent biocompatibility closely mirroring heart tissue. Tensile tests revealed that auxetic patches possessed superior elasticity and strain capacity exceeding cardiac tissue's physiological activity. Notably, Model III showed an equivalent modulus ratio and Poisson's ratio closely toward cardiac tissue, underscoring its outstanding mechanical potential as cardiac patches. Cyclic tensile loading tests demonstrated that Model III withstood continuous heartbeats, showcasing outstanding cyclic loading and recovery capabilities. Numerical simulations further elucidated the deformation and failure mechanisms of these patches, leading to an exploration of influence on mechanical properties with alternative design parameters, which enabled the customization of mechanical strength and Poisson's ratio. Therefore, this research presents substantial potential for designing cardiac auxetic patches that can emulate the deformation properties of cardiac tissue and possess adjustable mechanical parameters.

Using machine learning algorithms for predicting bridge vertical deflection

Machine learning (ML) is being increasingly used to ease structural health monitoring and management of bridges. Therefore, the main objective of this study is to apply two state-of-the-art ML algorithms, namely locally weighted learning (LWL) and K-Star for the prediction of vertical deflection of composite bridges. To accomplish the objective, 83 track loading tests were carried out at various bridges located in Vietnam and deflection data was collected for models’ development. Model's validation and comparison were carried out using different popular methods, namely mean absolute error, root mean squared error and R on both training (70%) and validation (30%) datasets. The results of this study indicate that the K-Star algorithm outperforms LWL in predicting the vertical deflection of composite bridges. Consequently, K-Star can serve as an effective tool for rapidly predicting vertical deflection, thereby facilitating more efficient bridge health monitoring and management. This efficiency can lead to significant time and cost savings in maintaining the structural integrity of composite bridges.