Challenge Journal Publications (TULPAR Academic Publishing)
Not a member yet
461 research outputs found
Sort by
Performance investigation of a mixed slab building with beam and ribbed slabs
Full text linkOver time deterioration in material properties, unauthorized modifications, or construction defects can negatively affect the seismic behavior of structural members. Therefore, the in-situ identification and performance analysis of reinforced concrete elements, carried out to ensure the safety of the existing building stock, have become a fundamental part of examining structural characteristics and developing disaster risk reduction strategies. In this study, the structural performance analysis of an existing reinforced concrete building with a mixed slab system was conducted by using the STA4CAD V13.1 software. For this purpose, nonlinear pushover analysis was performed for each seismic direction. As the existing reinforced concrete building did not satisfy the requirements for the single-mode method prescribed in TBDY (2018), a multi-mode pushover analysis was conducted for the structure. Based on the results of nonlinear multi-mode pushover analysis, the damage states of the structural members were determined, and the performance level of the structure was evaluated. The targeted performance level of controlled damage, as defined in the Turkish Building Earthquake Code-2018 TBEC (2018), could not be achieved for the analyzed residential-type reinforced concrete building. However, the collapse prevention performance level was determined due to the damage occurrence in the structural elements
Flowability and compressive strength of ternary blended cement mortar of coal bottom ash and ground cockle shell ash
Full text linkFlourishing cement industry to meet the demand of construction industry has negative impact to the global environment owing to the carbon emission during calcination of cement. At the same time, the disposal of coal bottom ash and cockle shell from coal power plant and cockle trade which pollutes the environment also need to be resolved. In view of circular economy, the present research aims to produce ternary blended cement consisting of coal bottom ash (CBA) and cockle shell ash (CSA) for sustainable mortar production. The research was conducted to determine the effect of CBA as partial cement replacement on flowability and compressive strength of CSA blended cement mortar. Seven mortar mixes consisting of CBA as supplementary cementitious material ranging from 0% to 60% by weight of cement were prepared. All specimens were water cured up to 56 days. The flowability test was conducted to assess the properties of the fresh state, while hardened properties were evaluated through compressive strength test at 1, 3, 7, 28, and 56 days. The results showed flowability decreased by 5% to 31% with increasing CBA content compared to the control mix. The use finer sized CBA forms a slightly stickier mortar mix with lower flowability. A combination 10% to 20% CBA is the best percentage to use for formation of CSA mortar with enhanced strength. However, a maximum strength of 23 MPa was achieved at 56 days with an optimal CBA replacement of 10%. This research demonstrates the potential by transforming industrial waste for low-carbon cement production to save the use of landfills for waste disposal and optimize consumption of non-renewable resources
Neuraxial anesthesia in pregnant patients with neurological disorders ‒ Safety and practice strategies: A review
Full text linkPregnant patients with neurological disorders face multifaceted challenges arising from both the physiological changes of pregnancy and the underlying neurological conditions. In this unique patient population, anesthesia management requires meticulous planning to ensure maternal and fetal safety while minimizing the risk of neurological complications. Neuraxial anesthesia emerges as a safe and effective option when implemented with appropriate patient selection, a multidisciplinary approach, and individualized anesthesia protocols. This review comprehensively evaluates the clinical benefits of neuraxial anesthesia in pregnant patients with neurological disorders, highlighting critical considerations in its application and potential risks. Drawing upon the existing body of evidence, it aims to promote the safe use of neuraxial techniques and enhance awareness of the challenges inherent in managing this patient group. Additionally, the review underscores the importance of anesthesiologists adopting individualized strategies that address the specific risks associated with neurological pathologies, optimizing the advantages of neuraxial anesthesia in obstetric care
Concrete strength monitoring and damage detection using piezoelectric-based wireless sensor
Full text linkConcrete stands as the predominant and extensively employed structural material in civil engineering. Timely evaluation of concrete strength is essential for maintaining structural safety and minimizing construction delays, thereby avoiding possible structural failures. This early check also ensures that concrete structures can bear loads during construction and throughout their service life. A significant challenge in the construction industry is accurately determining the strength of early-age concrete and identifying potential damage without destructive testing. Conventional techniques often require time-consuming procedures and can be impractical for real-time monitoring. To overcome this issue, IoT-based monitoring systems with piezoelectric sensors provide a practical approach for continuous strength monitoring and damage identification in concrete structures. This study utilized a piezoelectric lead zirconate titanate (PZT) sensor, employing a surface-bonding technique to attach the sensor to the cube specimens. The experimental phase spanned four weeks, including intervals of 7th, 14th, and 28th days by standard construction codes to assess necessary strength levels and identify any damage within the structure. This study verified the results obtained by the piezoelectric-based wireless sensor network are practical and reliable. Correlation coefficient values are analyzed to validate the relationship between data from IoT-based testing and compressive strength. All the results are presented in graphical format, confirming that this non-destructive approach can accurately predict concrete strength and identify structural damage. This study uniquely contributed by validating the use of piezoelectric sensors for continuous, in-situ monitoring of concrete, providing a novel approach to early damage detection and evaluating the structural health of the structure
Assessment of stresses and vibration behavior of concrete gravity dam under fluctuating hydrostatic force
Full text linkDam structure contributes to the socio-economic development of a country but zero probability of failure of such structure is a design concern. Hence, it is essential to monitor the dam condition under the fluctuating reservoir water and the vibration effect. In this investigation, four different cases of the reservoir depths are adopted to numerically analyze the hydrostatic and modal (free-vibration) behavior of a three-dimensional (3D) gravity dam. The impact of fluctuating reservoir water and uplift pressure on the dam's internal stresses (direct, principal, shear, and Von Mises) are evaluated to examine the location of maximum stress concentration. Under these cases, the maximum displacement along the longitudinal and vertical directions is explored. It can be revealed that case 4 (without tail-water) induces the maximum displacement on the top crest level and the peak normal stress concentrated at the heel region, respectively. This case also experienced the lowest time-period and largest frequency. In comparison to cases 2, 3, and 4, case 1 exhibit the largest crest level displacements along the x-direction that are 26%, 49%, and 86% higher, respectively. Compared to case 1, the normal stresses along the x-direction declined by 51.58%, 68.74%, and 58.25%, respectively for cases 2, 3, and 4. It can be revealed that the frequency is directly related, while the time-period is inversely proportional to the mode-shapes. Overall, this study envisages a comprehensive understanding of the dam’s performance, providing critical data to inform design decisions, safety assessments, and performance improvements
“Keeping it steady”: Anaesthetic challenges in insulinoma surgery
Full text linkInsulinoma is a tumor of the pancreas that secretes excessive insulin, causing recurrent hypoglycemia. The median presentation age of 47 years and a mild female preponderance. Most cases are benign, with only 10% showing malignant potential. A typical presentation involves Whipple's triad, which includes symptomatic hypoglycemia, fasting blood glucose below 50 mg/dL, and immediate relief of symptoms after glucose administration. This case report discusses the perioperative anaesthetic management of a 54-year-old patient with insulinoma who underwent laparoscopic enucleation. A comprehensive approach involving preoperative blood glucose optimization through medications and dietary adjustments, vigilant intraoperative monitoring with timely dextrose infusion during tumor manipulation, and careful postoperative control of rebound hyperglycemia using insulin infusion is essential for improved outcomes in these patients. The primary treatment is surgical enucleation, but managing perioperative glycemic fluctuations presents significant challenges for anesthesiologists
A discrete element method for evaluating the seismic performance of concrete gravity dam-reservoir systems under main shock-aftershock events
Full text linkDams are crucial for water supply, flood prevention, and hydroelectric power generation. Often located in seismically active regions, they are vulnerable to main shock-aftershock (MS-AS) sequences, which can compromise structural integrity and hydraulic safety. Critical aspects of dam response to MS–AS events remain unclear, particularly the required rest time between successive events and threshold AS-to-MS intensity measure ratios that could serve as predictors of additional damage. This study addresses these gaps by analyzing concrete gravity dam–reservoir systems of three heights (50 m, 100 m, and 150 m) using the developed discrete element–based approach coupled with displacement/pressure-based mixed finite elements for the reservoir. Empirical rest time equations were derived from 124 as-recorded ground motions, while seismic performance under varying intensity levels was evaluated using 14 as-recorded MS–AS sequences. Damage was quantified using discrete indices of base crack length, maximum base crack width, and maximum total upstream crack width. Results indicate that AS primarily propagate existing cracks at lower intensities, whereas higher intensities generate new cracks along the upstream face, increasing crack widths by 25–30% on average. The 50 m high dam remained within the mild damage category, while taller dams occasionally reached moderate levels, posing potential seepage risks. Threshold AS-to-MS ratios for four different intensity measures were identified. These findings provide mechanistic insight into crack propagation under MS-AS events, providing practical guidance for post-earthquake dam safety assessment, inspection prioritization, and incorporating sequential seismic effects into design and emergency planning
Erratum to: The impact of vagal nerve stimulation from the lateral neck region on venous cannulation pain: A randomized controlled trial
Full text linkThis article corrects an error in the authorship listing of the original publication:Canikli Adiguzel S. The impact of vagal nerve stimulation from the lateral neck region on venous cannulation pain: A randomized controlled trial. Chall J Perioper Med. 2025; 3(2):48–53. https://doi.org/10.20528/cjpm.2025.02.003Due to an editorial error, the original article listed only the corresponding author. The correct authorship should be as follows:Senay Canikli Adiguzel, Emre Can Soydan, Ebru Kayikci, Mustafa Suren, Ismail OkanThe Editorial Office of Challenge Journal of Perioperative Medicine apologizes for this error.The scientific content of the article remains unchanged
Tea waste ash: Characterization, pozzolanic activity and effects on the fresh properties of cement pastes
Full text linkIt is a well-known fact that the use of agricultural wastes in cementitious composites by turning them into ash provides both ecological and economic benefits. Tea factories in Türkiye are located in the Eastern Black Sea region. Tea waste generated in factories locally causes environmental problems. This study focuses on the usability of the wastes left over from the products processed in the tea factory. Tea waste from Artvin, Türkiye was turned into ash at 850 °C. Physical, chemical, mineralogical, thermogravimetric and morphological properties of tea waste ash were examined. Pozzolanic activity test was performed to determine its usability in cement systems. Blended cement pastes were prepared by substituting up to 10% tea waste ash. Physical and chemical properties of blended cement pastes were determined. As a result, the tea waste ash was found to contain a high proportion of K2O. The waste material does not show pozzolanic properties. The hydration of cement pastes has accelerated with tea waste ash. Tea waste ash substitution has increased standard consistency water of blended cement pastes. Tea waste ash substitution up to 8% provided the initial setting time included in the standard. It was concluded that tea waste ash could be used as a setting accelerator