Challenge Journal Publications (TULPAR Academic Publishing)
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Effect of resin amount on the damping properties of polymer concrete
Full text linkIn the construction and infrastructure sector, efforts are being made to find faster and more efficient materials. Polymer concrete (PC) challenges traditional concrete with its fast setting, durability and abrasion resistance. While studies on PC strength are abundant in the literature, studies on the effects of resin amount on damping capacity are fewer than mechanical performance. In this paper, the effect of resin proportion on damping capacity is investigated by modal tests. PC mixtures in the production with different resin proportions (11‒19%) were poured into molds of 10x25x500 mm, using aggregates of up to 3.15 mm in size. After 14 days, the natural frequency and damping ratios of the specimens up to 1000 Hz were determined in modal tests. While the damping ratio (DR) decreased in resin contents up to 17%, the results of the specimens with 19% resin ratio increased. However, when the products with the same resin ratio are analyzed, the random distribution of the aggregate affects the damping capacity. The main reason of negative correlation between resin amount and DR is the filler amount in the mixture. Because of the production consistency, fluidization of all the mixtures is prevented by adding fillers. Therefore, the impact of the resin amount on DR is limited or even negative. Besides that, to compare measurement results finite element method (FEM) analyzes are conducted. It can be said that the natural frequencies are not suited well especially in high frequency ranges due to frequency dependent properties (visco-elastic) of PC
The impact of openings on ferrocement I-beams: a study on metallic and non-metallic mesh reinforcement
Full text linkThe primary objective of this investigation is to assess the influence of openings on the structural performance of ferrocement I-beams, incorporating diverse metallic and non-metallic mesh reinforcements. Sixteen beams underwent testing utilizing a four-point loading system until failure, categorized into four groups based on the type of mesh reinforcement. Each group comprised a control I-beam without openings and three additional beams featuring one, two, and three openings, respectively. To ensure consistent reinforcement weight, the four groups were reinforced with three layers of welded steel meshes, two layers of expanded metal meshes, two layers of Tensar meshes, and eight layers of Gavazzi meshes. Comparative analysis of the experimental outcomes was conducted with finite element models utilizing Abaqus. Therefore, there was good agreement between the experimental and numerical results. The findings showed that beams with no openings, one, and two openings reinforced with Gavazzi meshes had the highest ultimate load compared to other tested beams, while beams with three openings, those reinforced with expanded metal meshes had the greatest ultimate loads. Placing three openings in beams, with dimensions of 100×50 mm (two of these openings are approximately 10 cm apart from each edge while the third opening is located at mid-span), reduced the load-to-weight ratio by about 20.7%, 12.9%, 8.2%, and 23.8% for welded beams, expanded beams, Tensar beams, and Gavazzi beams, respectively, compared to the beams with no openings
Perioperative complications in patients undergoing urological surgery with spinal anesthesia: A prospective, observational study
Full text linkBackground: Spinal anesthesia is widely used as the primary anesthesia method in urological surgeries, and this prospective observational study aimed to evaluate the associated complications.Materials and Method: Demographic data, procedures, and spinal anesthesia-related complications (e.g., hypotension, bradycardia, and headache) of patients who underwent urological surgery with spinal anesthesia were recorded perioperatively. Patients were questioned about complications on the 5th and 14th postoperative days.Results: Mean arterial pressure decreases in those administered intraoperative hyperbaric bupivacaine were higher at the 5th (p=0.010), 10th (p=0.003), and 15th minute (p=0.001) than in those administered levobupivacaine and lidocaine. In patients administered crystalloid and colloid solutions, an increase in hypotension was observed at the intraoperative 10th minute (systolic arterial pressure (SAP): p=0.008, diastolic arterial pressure (DAP): p=0.011) and 15th minute (SAP: p=0.017). Post-dural puncture headache (PDPH) occurred on days 1 and 2 in 7 patients and resolved within 3 days. Two patients reported leg pain and one patient reported gluteal numbness with bupivacaine. A majority of the patients (83%) stated that they would prefer spinal anesthesia if they were to have surgery again.Conclusions: Identifying perioperative complications in urological surgeries performed under spinal anesthesia helps in effective management and has implications for clinical practice
Investigation of structural performances of historical building elements made with local materials using the finite element method
Full text linkThe structural performance of the materials used in historical buildings can be damaged, usually due to natural events or human-induced interference. Historical buildings in the Southeastern Anatolia Region were generally built with local materials such as stone and brick. This situation should be seen as a factor that may cause severe structural damage in buildings located on a regionally active fault line. Within the scope of the study, the materials used in the region were discussed, and a numerical model representing the behavior of the materials against an earthquake that could occur on the fault line was used. Stone, brick and concrete material definitions were made for the prototype of the arch form modeled with SAP2000, and time-history analyses were carried out separately for each material. Concrete material behaviors, frequently used in buildings constructed today, are also included in the analysis for comparison. As a result of the study, it has been observed that local materials do not have sufficient tensile strength against earthquakes compared to concrete material and that the structures may face the risk of collapse in case of seismic movements in the region
Influence of the distance between vertical cylinders positioned in a row on the wind load on them
Full text linkThe silos and vertical cylindrical tanks of small volumes are often built in batteries, at short distances between them. As a result of their close location, the wind load on them increases. In the European standard EN 1991-1-4:2005+A1:2010 exists a methodology for determining this increase, which is dependent on the ratio a/d, where a is the distance between the facilities and d is their diameters. Unfortunately, this methodology is applicable for ratios a/d > 2.5. In cases where the values are smaller, the standard transfers to the national annexes. In the available to the author annexes, including the Bulgarian one, there is nothing on the subject. Moreover, the necessary information could not be found in the public scientific literature. Only in the Australian/New Zealand standard AS/NZS 1170.2:2011 are written some simple rules for closely spaced vessels. To fill this gap, multiple models of closely spaced cylindrical bodies has been created by the author. A computer fluid simulation (CFD) program is used for this purpose. In the present study, the bodies are arranged in one row and the wind blows them perpendicularly. Through these computer models is determined how the wind load changes due to their proximity. In contrast to what is stated in EN 1991-1-4:2005+A1:2010, the dependence is not linear, and the influence of the close arrangement of the bodies decays much faster. On the other hand, this influence should be considered at much greater distances between bodies than stated in AS/NZS 1170.2:2011
Optimum design of reinforced concrete beam sections with JAYA algorithm
Full text linkSection design is an important process for designing reinforced concrete structures because of the existence of factors such as bearing capacity and cost. After defining the initial cross sections for reinforced concrete elements, reinforcement amounts are calculated within the framework of certain rules and regulations. In the classical method, optimum cost and reliable structure can be designed by trial and error. Designing with the classical method is quite time-consuming. As in different fields, metaheuristic algorithms are employed to civil engineering applications to reach the optimum solution. In this study, unlike other examples from the literature, the optimum cost design of reinforced concrete beam cross-section was done, adding torsional moment to bending moment and effects of shearing force through the use of the JAYA algorithm. The optimum cost design of a reinforced concrete beam section under the effects of torsional moment, bending moment and shear force is performed. The design is done according to the rules specified in ACI 318 (Building code requirements for structural concrete), as it is well-known and used in many international projects. For the purpose of this study, cross-sections of 10 different reinforced concrete beam cross-sections were designed under 5 different loads for 2 different concrete classes through MATLAB software, with the aim of finding the optimum beam cross-section. A reinforced concrete beam is designed under different torsional loads and for different concrete classes and it is aimed to find the optimum beam cross-section. It shows the effect of torsional force on reinforced concrete beam cross section and reinforcement by using different torsional loads. It was observed that the algorithm used tends to approach the optimum result, increasing the area of concrete with lower unit cost or reducing the distance between stirrups. It was concluded that Jaya algorithm performs effectively with respect to optimizing reinforced concrete beams. The algorithm used can be applied to different reinforced concrete elements
Suprainguinal fascia iliaca plane block for surgical anesthesia of thigh: A case report for excision of a giant mass
Full text linkSuprainguinal plane block was defined by Hebbard in 2009 for postoperative analgesia purposes. It is aimed to block the femoral nerve, lateral femoral cutanaeus nerve and obturator nerve. In this case, we presented the successful surgical management of suprainguinal block in excision of a mass in the thigh. During the surgery, which lasted 80 minutes, additional analgesic was needed only during the femur curettage. Postoperative pain scores were low and the patient was discharged the next day
Reinforcement of concrete beams using waste carbon-nanoclay-fiberglass laminate pieces
Full text linkIn the last few decades, strengthening of structures in need of repair with fiber reinforced polymer (FRP) composite materials produced with different fiber types has gained great importance. Within the scope of this experimental study, the usability of hybrid glass and carbon composite laminates produced for different purposes and later cut into waste was investigated for concrete reinforcement. Hybrid composite laminates were produced in the form of glass-carbon-glass and carbon-glass-carbon, and the effect was investigated in two different sequences in the study. In addition, there are 3 different rates of nanoclay (0.50%, 0.75% and 1.25%) in the production of composite materials, and the effect of nanoclay ratio was investigated. In the study, two different numbers of composite laminates were adhered to the concrete samples produced in 70x70x280 mm dimensions and subjected to flexural strength test. In the Carbon-Glass-Carbon series using triple waste laminate pieces, the highest flexural strength was reported in the CGC-0.75-3 series, which achieved an increase of approximately 55% and 42% compared to the Control and Control-E series. It was determined that the effectiveness of the reinforcement technique of concrete with laminates in flexure did not change significantly depending on the number of laminate pieces. The main mode of failure in the experimental work was due to concrete fracture
Evaluation of Analgesic Nociceptive Index in intraoperative and postoperative pain management in general anesthesia applied with two different methods
Full text linkAim: Effectiveness of analgesic nociceptive index (ANI) monitoring in predicting both intraoperative and postoperative early pain in neurosurgery patients undergoing lumbar spinal surgery. The patients were administered general anesthesia using different anesthesia management techniques.Method: The study included a total of 60 patients with American Society of Anesthesiologist (ASA) I-III. The patients were randomly divided into two groups of 30 each using the closed envelope method. Group T received total intravenous anesthesia (TIVA) with remifentanil-propofol, while Group D with desflurane-remifentanil. Non-invasive ANI monitoring was applied to patients undergoing lumbar spinal surgery, and ANI, heart rate, systolic/diastolic arterial pressure values were recorded before and after induction, skin incision, major muscle incision, laminectomy, right-left fasciectomy, screw fixation, after extubation and during the postoperative period. Post-operative heart rate, ANI value, mean arterial pressure values, and visual analog scale (VAS) values were measured.Results: No statistically significant difference was found in terms of the demographic data of the patients. According to the groups, no statistically significant difference was found between the ANI and VAS measurements of the cases at the postoperative 5th minute (P=0.261), postop 10th minute (P=0.379), postop 15th minute (P=0.673), postop 30th minute (P=0.784) and postop 60 minute (p =0.750).Conclusions: In our study on lumbar spine surgery, we could not detect any significant relationship between ANI monitoring and VAS values in the early postoperative period. There was no difference in ANI and VAS with either anaesthetic technique. In light of the results of our study, we believe that more studies are needed on the use of ANI monitoring in the early postoperative period