Challenge Journal Publications (TULPAR Academic Publishing)
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Experimental performance analysis of concrete-filled steel column to concrete-filled steel beam connections
Full text linkExisting literature and practical engineering practice have comprehensively examined the behaviour of concrete-filled steel tubular (CFST) columns, CFST beams, and their associated connection systems involving either steel or reinforced concrete (RC) beams. Despite these advancements, limited research has focused on the direct beam–column interaction in fully CFST-to-CFST connection configurations. The absence of established design specifications and systematic experimental evidence has hindered the reliable adoption of such connections in structural applications. This feasibility study addresses this knowledge gap by conducting an integrated theoretical and experimental investigation into the structural performance of moment-resisting connections between CFST columns—locally strengthened with internal stiffening plates and configured with external bolted flange connections—and CFST beams of matching geometry. To provide a meaningful benchmark, a comparable hollow steel column–steel beam connection with identical cross-sectional dimensions and bolt arrangements was also evaluated. The experimental setup involved cyclic loading tests designed to capture load–rotation behaviour, quantify flexural stiffness, and identify critical limit states governing connection performance. Detailed measurements of moment–displacement response, local deformation patterns, and strain distribution were collected to assess connection rigidity, load-transfer mechanisms, and potential vulnerability to local buckling. The resulting data allowed for direct comparison between the proposed CFST-to-CFST connection configuration and the hollow steel reference specimen, enabling a clearer understanding of the composite action and confinement effects provided by the infilled concrete. The findings contribute foundational evidence for the feasibility of those moment connections and offer preliminary insights to support future analytical modelling, design recommendations, and full-scale implementation
Improving bond performance of 3D-printable earth-based mortar reinforced with jute fibers
Full text link3D printing technology has transformed the construction industry by enabling rapid and cost-effective production of complex geometries. However, it faces significant challenges, including sustainability concerns due to cement's environmental impact and reinforcement issues arising from the incompatibility of traditional steel. These challenges necessitate the development of innovative material solutions. This study aims to enhance the bond strength between sustainable earth-based mortar and jute fibers used as reinforcement in 3D printed structures by exploring the effects of different treatments and compositions. Bond strength was evaluated by considering the effect of different treatments on the resistance of the fiber to being pulled out of the mortar. Pull-out tests were conducted on specimens with varying compositions and treatments. Results demonstrated substantial improvement in bond performance; specifically, the reference sand-free earth-clay mortar exhibited the lowest interfacial shear strength of 0.30 MPa. The most remarkable enhancement was observed in specimen which jute fibers pre-treated by immersion in mud slurry, which showed a 147% increase, reaching an interfacial shear strength of 0.74 MPa. Combining sand addition and fiber pre-treatment, however, did not yield additional benefits. These results indicate that simple, cost-effective local treatments can notably enhance fiber-matrix bond strength in 3D-printed earth-based structures without necessitating additional equipment or significant expense
Impact of screw arm angle, material property, and applied force on the behavior of maxillary expander
Full text linkA unilateral or bilateral posterior crossbite is a common and severe malocclusion characterized by maxillary transversal deficiency. Various expansion appliances are employed to correct this condition. The objective of this study was to evaluate the forces transmitted to the teeth and the deformation of the expander appliance resulting from modifications to the screw arms of a slow maxillary expander with different angles, using finite element analysis. All models were created in SolidWorks and analyzed using ANSYS Workbench. The analysis revealed that the models with different angular configurations of the expander screw arms (0°, 15°, and 30°) exhibited very similar reaction forces on the teeth. However, significant differences in deformation values were observed among the models. The most effective parameter is the force applied to the expander with a rate of 46%, followed by the arm angle with a rate of 44%, while the effect of material type is 10%. The most significant conclusion that can be drawn from these findings is that the arm angle is as important as the force applied to the expander. In situations where the force that can be applied is limited by various factors, it can be demonstrated that altering the arm angle can lead to the achievement of the desired outcome
Effect of dimensions of specimens on the impact performance of concrete
Full text linkMechanical properties of concrete are size dependent. While many reports have discussed the size effect of the test specimen on the static properties of concrete, research on the effect of cross-sectional dimensions of the concrete beams on its impact performance is still scarce. This research experimentally evaluates the relationship between the cross-sectional dimensions and orientation of the concrete beam specimens on their impact performance. Repetitive drop-weight test was used to evaluate the impact energy absorption capacity of different concrete beams. A loading protocol to evaluate the impact energy of concrete beams having different cross-sectional dimensions was proposed. The results revealed that the impact performance of concrete is size dependent. Strong proportional relationships between the moment of inertia, cross-sectional area and impact energy were found. As the moment of inertia and cross-sectional area of the test specimen increase, its impact energy exponentially increases. Furthermore, a linear proportional relationship was found between the normalized impact energy and the normalized cross-sectional area × moment of inertia. This means that the impact performance of concrete beams depends on both their cross-sectional area and orientation. The proposed loading protocol has been proven to be able to accurately evaluate the impact energy of concrete specimens with significantly varying impact performance while importantly saving time
Evolutionary process and mechanical properties of polymers: A comprehensive review
Full text linkThe growing demand for innovative construction materials has driven the exploration of polymer-based composites due to their enhanced mechanical performance and potential environmental benefits. However, a clear understanding of the historical development, classification, and structural behavior of polymers in construction remains limited. This review aims to bridge this gap by synthesizing current knowledge on the historical evolution, mechanical benefits, chemical benefits, drawbacks and real world applications of polymers in construction. The study focuses on key thermosetting resins such as polyester, epoxy, vinyl ester, and PET and assesses their mechanical properties relevant to structural applications. To address the lack of integrated insight in the literature, the review compiles and compares data from various primary sources. Mechanical properties such as tensile, compressive, and flexural strength are evaluated to determine the suitability of each polymer for construction use. The outcomes indicate that epoxy resins demonstrate superior tensile and flexural strength, while polyester and polyethylene terephthalate PET offer notable advantages in compressive resistance and sustainability. Overall, the findings provide a consolidated understanding of polymer development and performance, offering valuable guidance for researchers and engineers aiming to enhance material efficiency, durability, and environmental responsibility in the construction industry
Cost-effectiveness of fascial plane blocks in laparoscopic cholecystectomy: A retrospective study
Full text linkBackground: Fascial plane blocks have increasingly been used in recent years as a component of multimodal analgesia. The aim of this study was to evaluate the impact of fascial plane blocks, applied for postoperative analgesia, on hospital costs in laparoscopic cholecystectomy (LC) procedures.Materials and Methods: This retrospective, single-center study included 1414 patients who underwent elective LC under general anesthesia between 2020 and 2025. Patients were divided into two groups: those who received fascial plane blocks (Group M, n=346) and those who received the standard analgesia protocol (Group S, n=1068). Total hospital invoice costs at discharge, length of hospital stay, demographic characteristics, ASA scores, and comorbidities were compared between the groups.Results: No significant differences were observed between the groups regarding age, sex, or comorbidity rates. Hospital length of stay was similar. In the overall analysis covering 2020–2025, hospital costs were significantly lower in the fascial plane block group (p<0.001). Subgroup analyses by year revealed a significant cost difference in favor of the fascial plane block group only in 2024.Conclusions: In addition to providing effective analgesia, fascial plane blocks reduced hospital costs in LC procedures, contributing as a cost-effective component of multimodal analgesia
Influence of connector forces on the expansion configuration of a hexagonal modular floating structure
Full text linkThe preliminary design of a hexagonal modular floating structure (HMFS) system includes two configurations: U-shaped and V-shaped, which link seven hexagonal modules that create a network of connectors. The connector force is a crucial consideration in the layout of the connector network, as it must sustain the forces generated by wave motion due to its influence on the stability and safety of the modular floating structure. This paper presents the development of the HMFS connector network and the estimation of the connector horizontal force influence by two types of configurations. The design concepts of these configurations for HMFS configurations are proposed where analysis was implemented for regular wave in various directions of 0°, 30°, 45°, 60°, 85°, and 90°. The impact of these various wave directions and the HMFS configurations on the connector force is analysed accordingly. According to this research finding, the connector force in U-shaped configuration is higher than the load in V-shaped of HMFS configuration. The connector force of the V-shaped configuration is arranged in hexagonal vertices (VV-shaped) facing wave direction receive a higher connector force than hexagonal parallel sides (VP-shaped) facing wave directions. The determination of horizontal connector load of hexagonal modules with varying configurations enabled the designer to estimate the horizontal connector load for various conceptual designs of hexagonal shapes, such as dock ships, yacht terminal and floating cities
Effect of elevated temperatures on mechanical properties of hydraulic lime-based mortar in historical structures
Full text linkHistoric masonry structures are subjected to various negative effects from the time they are built. As a result, these structures suffer damage, leading to restoration and reinforcement efforts. Hydraulic lime-based mortars (HLMs), which are compatible with the nature of historic structures, are used in restoration and reinforcement. This study investigated the fire resistance of hydraulic lime-based mortars. Within the scope of this study, HLMs were prepared in accordance with restoration standards, and prism specimens were prepared with HLMs. These specimens were exposed to high temperatures ranging from 200 °C to 700 °C, and bending and compression tests were conducted on the specimens exposed to temperature. During the elevated temperature tests (ETTs), a total of 27 specimens were prepared, including three test specimens, one temperature monitoring specimen for each temperature, and three reference specimens. While the reference specimens were tested at room temperature, the other specimens were kept until they reached room temperature after the ETTs were completed and then tested under the same conditions as the reference specimens. No tests were performed on the temperature monitoring specimens, and these specimens were only used to monitor the temperatures inside the specimens with thermocouples placed inside. As a result of the experimental studies and evaluations, it was determined that the HLMs began to lose their mechanical properties with increasing temperature, but even after 700 °C, they still exhibited mechanical properties observed in low-grade mortars
The impact of vagal nerve stimulation from the lateral neck region on venous cannulation pain: A randomized controlled trial
Full text linkBackground: As the cranial nerve with the longest and widest distribution area of the body, the vagus nerve (N.Vagus) has both antinociceptive and neuromodulatory effects and plays a role in the regulation of the heart rate. The objective of this study is to investigate the impact of cold stimulation on vascular access discomfort and heart rate variability, specifically by separately stimulating the N. Vagus nerve on both the right and left sides of the neck thereby assessing any lateralization effect.Methods: 140 patients, ranging in age from 18 to 75, were randomly assigned to one of two groups: Group Left (Group L) or Group Right (Group R). Following cold application to the left lateral neck region of Group L and the right lateral neck region of Group R, venous cannulation was performed. Prior to, following, and subsequent to vascular access, the heart rate, noninvasive blood pressure, oxygen saturation, and numeric pain scale (NRS) values for venous cannulation pain of the patients were documented.Results: Average heart rates and average heart rates after cannulation were considerably lower in both groups after vagal stimulation (p0.05). The mean heart rate change percentages before and after vagal stimulation were 7±5.8% and 7.1±7.0% in group L and group R respectively, suggesting that heart rate variability was greater in Group R, although this difference was not statistically significant (p>0.05). NRS values were found to be 2.64±1.28 in Group L and 2.85±1.62 in Group R, with no significant difference (p>0.05).Conclusion: While heart rate variability exhibited more prominence on the right side, the difference was not statistically significant. Analyzing the analgesic impact revealed no discernible difference between the analgesic effects of stimulation from the right and left sides.------------------------------------------------------This article has an Erratum. Please see: https://doi.org/10.20528/cjpm.2025.03.00
Retrospective evaluation of analgesia approaches in patients undergoing thoracic surgery over the last one year: A single-center study
Full text linkObjective: Providing adequate analgesia after thoracic surgery plays an important role in preventing pulmonary complications while accelerating postoperative recovery. This study aimed to retrospectively evaluate the effectiveness of analgesia approaches applied to patients who underwent thoracic surgery at Atatürk University Research Hospital in the last year. This study aimed to retrospectively evaluate the effectiveness of analgesia approaches applied to patients who underwent thoracic surgery at Atatürk University Research Hospital in the last year by comparing different analgesia methods in terms of rescue analgesia requirements.Method: This retrospective study was conducted by examining the archive files of patients who underwent thoracic surgery between 2024-2025. Patients were classified according to the analgesia methods applied. The analgesic method used was compared according to the type of surgery applied and the need for rescue analgesia.Results: Intravenous opioid was determined as the most frequently used analgesia method in the analyzed patient group. Rescue analgesia requirement was observed to be the lowest in patients who underwent epidural analgesia. In patients who underwent paravertebral block, it was observed that effective analgesia was provided and the need for rescue analgesia decreased.Conclusion: Epidural analgesia and paravertebral block stand out as effective methods in analgesia management after thoracic surgery. However, the specific advantages and complication risks of each method should be considered. Secondary objectives of this study include analyzing the relationship between analgesia selection and surgical type (VATS and thoracotomy) and determining the choice of analgesia method and its rationale. It is thought that the findings of this study will contribute to the determination of optimal analgesia strategies after thoracic surgery