Pressure Test Research Articles

Temporal consistency loss for physics-informed neural networks

Physics-informed neural networks (PINNs) have been widely used to solve partial differential equations (PDEs) in a forward and inverse manner using neural networks. However, balancing individual loss terms can be challenging, mainly when training these networks for stiff PDEs and scenarios requiring enforcement of numerous constraints. Even though statistical methods can be applied to assign relative weights to the regression loss for data, assigning relative weights to equation-based loss terms remains a formidable task. This paper proposes a method for assigning relative weights to the mean squared loss terms in the objective function used to train PINNs. Due to the presence of temporal gradients in the governing equation, the physics-informed loss can be recast using numerical integration through backward Euler discretization. The physics-uninformed and physics-informed networks should yield identical predictions when assessed at corresponding spatiotemporal positions. We refer to this consistency as “temporal consistency.” This approach introduces a unique method for training physics-informed neural networks (PINNs), redefining the loss function to allow for assigning relative weights with statistical properties of the observed data. In this work, we consider the two- and three-dimensional Navier–Stokes equations and determine the kinematic viscosity using the spatiotemporal data on the velocity and pressure fields. We consider numerical datasets to test our method. We test the sensitivity of our method to the timestep size, the number of timesteps, noise in the data, and spatial resolution. Finally, we use the velocity field obtained using particle image velocimetry experiments to generate a reference pressure field and test our framework using the velocity and pressure fields.

Seroja Tropical Cyclon Destruction Case Study: Permanent Slope Protection Evaluation at Downstream of Rotiklot Dam Nomenclature Building, East Nusa Tenggara, Indonesia

Abstract Rotiklot Dam was one of some infrastructures which was affected by the Seroja Tropical Cyclone in East Nusa Tenggara Indonesia in April 2021. There are several landslides at the downstream of the dam that can threaten the safety of the dam, especially at the downstream of the nomenclature building. The right design of permanent slope protection must be determined in a limited time. Geotechnical investigations such as boring, resistivity survey, standard penetration test, and water pressure test were conducted in a short time. Back analysis method was carried out to find extreme soil parameters conditions. The slope protection must meet the national standard minimum safety factor or greater than 1.5. Safety factors of slope protections are evaluated by a finite element method to get the safety factor and maximum total displacements. Every stage of slope protection can give the optimal safety factor values which are required or greater than 1.5, however backfill material will give more load and decrease the safety factor value.

Development and performance testing of a chamber for absorbed dose in water absolute measurement for 125I brachytherapy seeds

The application of more and more low-energy, low-dose-rate photon radiation seeds in brachytherapy. According to the TG43 report and TG43-U1 report issued by the American Association of Physicists in Medicine, both apparent activity and air kerma strength are physical characterization parameters of brachytherapy seed strength,which are needed to convert into water absorbed dose at the depth of 1 cm. At present, the method of obtaining the water absorbed dose is to convert the air kerma strength, the uncertainty of results exceeds 5% (k = 1), which could reduce the cure rate of the treatment. In order to address this issue ,the China Institute of Atomic Energy has designed a device that can directly replicate the water absorbed dose of 125I brachytherapy seeds,which is an extrapolation chamber embedded with water equivalent material. In order to evaluate the performance of the extrapolation chamber, a series of experiments were carried out, including partial pressure test, leakage current, saturation curve, response linearity, collection area and zero point position. The test results show that the performance parameters of the extrapolation chamber meet the relevant requirements.

Extension Mechanism of Water-Conducting Cracks in the Thick and Hard Overlying Strata of Coal Mining Face

It is of great significance for coal safety production and water resource protection in the Yuheng mining area to master the evolution law of water-conducting fractures under the condition of thick and hard overburden. This research focuses on the 2102 fully mechanized mining face in the Balasu Coal Mine as the research background. The fracture evolution and strata movement characteristics in thick and hard overlying strata are simulated and analyzed by combining numerical simulation with physical simulation, and the formation mechanism of a water-conducting fracture in the overlying strata is revealed and verified by field measurements of the development height of “two zones”. The results show that the anisotropy of fracture propagation in low-position overlying strata is high, and the fracture propagation in high-position overlying strata is mainly vertical, which indicates characteristics of leapfrog development. The number and development height of fractures undergo the change–growth process of “slow–rapid–uniform”. Multiple rock strata together form a complex force chain network with multiple strong chain arches. The local stress concentration leads to the initiation of micro-cracks in contact fractures, and the cracks gradually penetrate from bottom to top and then the strong chain arches are broken. The water-conducting cracks in overlying strata show a dynamic expansion process of “local micro-cracks–jumping cracks–through cracks–water-conducting cracks”. The fracture between the caving zone and fracture zone presents obvious layered characteristics, the overall shape of the water-conducting fracture zone is “saddle-shaped”, and the maximum development height lags behind the coal mining face by about 180 m. Through the observation of water injection leakage and borehole TV observation of three boreholes under underground construction, combined with the results of water pressure tests, it is comprehensively determined that the height of the water-conducting fracture zone is 103.68~107.58, and the fracture–production ratio is 31.42~32.60, which is basically consistent with the results of numerical simulation and physical simulation. This research provides theoretical guidance and a scientific basis for coal mine water disaster prevention under similar geological conditions.

Effects of Hydrostatic Pressure and Cation Type on the Chloride Ion Transport Rate in Marine Concrete: An Experimental Study.

The effect of hydrostatic pressure and cation type on chloride ion transport in marine underwater concrete cannot be ignored. The study of the chloride ion transport behavior of concrete under the effect of hydrostatic pressure and cation type coupling can provide a basis for durability design and the protection of marine concrete. In this work, the chloride ion transport behavior of marine concrete in four common chloride salt solutions under different hydrostatic pressures is studied by a hydrostatic pressure test device developed by the authors. The results show that hydrostatic pressure and its action time significantly influence the chloride ion transport behavior in marine concrete; the higher the hydrostatic pressure of concrete, the faster the chloride ion transport rate. The longer the time, the more chloride ions accumulated in the same position, and the farther the chloride ion transport distance. Cation type has a certain influence on the transport process of chloride ions. Under the same test conditions, the chloride ion transport rate in a divalent cation solution is about 5% higher than that in a monovalent cation solution. The results also show that the chloride ion binding capacity under hydrostatic pressure is only 10~20% of that under natural diffusion. Using the test results, a predictive model of a chloride ion apparent transport coefficient based on the hydrostatic pressure and hydrostatic pressure action time corrected by a cation type influence coefficient is established.

The change in Baroreflex Regulation of Heart Rhythm after “Dry” Immersion Appears during Orthostasis, but not Lower Body Negative Pressure Test

The ratio of low-frequency (LF, ~0.1 Hz) waves of RR interval duration (RRI) and systolic blood pressure (SAP) reflects the cardiac baroreflex sensitivity (BRS). Gravitational unloading (GU) may alter BRS during the passive orthostatic test (HUT) and lower body negative pressure (LBNP) test. Both effects cause blood redistribution to the lower body, but HUT is accompanied by greater unloading of sinocarotid baroreceptors than LBNP and activation of the vestibulosympathetic reflex but GU effects on BRS in these tests have not been directly compared previously. In this study we tested the hypothesis that the effect of “dry” immersion (DI, on-ground model of GU) on BRS in the same subjects will be more pronounced during HUT than during LBNP, which causes a comparable decrease in stroke volume. Nine healthy men participated in two test sessions (before and after 7-day DI) consisting of five 3-min HUT (65°) and five 3-min LBNP (–35 mmHg) with averaging the parameters in each test. Wavelet analysis was used to determine the amplitude of the RRI and SAP waves in the range of 0.05–0.13 Hz. The amplitude of LF waves of SAP increased in both tests, after DI - more significantly in HUT. The amplitude of LF RRI waves decreased in the two tests; the degree of decrease did not differ between tests and did not change under the influence of DI. The α-coefficient (the ratio of the amplitudes of RRI and SAP LF waves) decreased equally in the two tests before DI, but after DI, the degree of α-coefficient reduction increased in HUT test but did not change in LBNP test. Thus, the effect of DI on BRS is evident in HUT, but not in LBNP, which may be explained by the more pronounced influence of HUT on the mechanisms of neural control of heart rhythm.

Experimental study of air leakage of reinforced concrete panel with cracks

Evaluation of the leakage rate is necessary for infrastructure where hermetic performance holds critical importance. This study conducted a test to evaluate the air leakage rate of cracked reinforced concrete panels. Hollow beam specimens with an air chamber in the web were prepared to provide a relatively simple setup for airtight pressure testing under 200 kPa pressure. While testing, the lower flange of the beam specimen was subjected to tension cracking under transverse loading, and air pressure was applied to the air chamber of the beam to measure the air leakage rate through the flange plate as the magnitude of loading increased. The test variables were the differential air pressure, flange plate thickness, and reinforcement ratio. The test results showed that the leakage rate increased in proportion to the differential pressure. When the reinforcement ratio increased from 0.7 to 1.3 %, the leakage rate decreased by 90 %. When the plate thickness increased from 75 to 100 mm, the leakage rate decreased by 91 %. The analysis of the test results showed that the leakage rate was proportional to the cube of the crack width (R2 = 0.91–0.95), which agreed with existing prediction models. When the crack width at rebar location was used, the existing models showed the best predictions for test results. This result indicates that to accurately predict the air leakage rate of reinforced concrete members, the critical crack width at the location of reinforcement (i.e. the smallest crack width in the member thickness) is more important than the crack width at the member surface.

Closed vessel burning rate measurements of composite propellants using microwave interferometry

AbstractBurning rate as a function of pressure is one of the primary evaluation metrics of solid propellants. Most solid propellant burning rate measurements are made at a nearly constant pressure using a variety of measurement approaches. This type of burning rate data is highly discretized and requires many tests to accurately determine the burning rate response to pressure. It would be more efficient to measure burning rate dynamically as pressures are varied. Techniques used to make transient burning rate measurements are reviewed briefly and initial results using a microwave interferometry (MI) technique are presented. The MI method used in tandem with a closed bomb enables nearly continuous measurement of burning rates for self‐pressurizing burns, capturing burning rate data over a wide range of pressures. This approach is especially useful for characterization of propellants with complex burning behaviors (e. g., slope breaks or mesa burning). The burning rates of three research propellants were characterized over a pressure range of 0.101–24.14 MPa (14–3500 psi). One research propellant exhibited a slope break at a pressure of 6.63 MPa (960 psi). Using MI in a closed pressure vessel, 14 propellant strand burns resulted in a nearly continuous burning rate curve over a pressure range of 0.41–24.13 MPa (60–3500 psi) that reasonably matched conventional burning rate measurements. The development of this technique provides an opportunity to quickly characterize the burning rate curve of solid propellants with greater fidelity and efficiency than traditional quasi‐static pressure testing techniques.

Based on the strong oxidant AP adjustment strategy to obtain Al/AP@PVDF composite material with excellent energy release performance

In this paper, ammonium perchlorate (AP) as a strong oxidant has been added into Al/polyvinylidene difluoride (PVDF) nanothermites. Based on homogeneous structure of PVDF, shorter reaction contact between components can be obtained for more outstanding ignition and combustion performance. Water contact angle experiments were conducted to evaluate the hydrophobicity of the composite films, indicating that the suitability of composite material has enhanced under wet environment. According to TG-DSC results, the thermal decomposition of AP can improve the whole heat release process, which theoretically has excellent combustion performance advantages. Constant volume pressure tests were conducted to assess the energy release properties of the films compared with Al@PVDF films. Combustion performance in air was evaluated by employing optical sensors and a high-speed camera to measure factors such as the ignition delay time, light intensity and combustion flame propagation. After adding 15 % AP, the maximum pressure of Al/AP@PVDF film is 0.0960 Mpa, and that of Al@PVDF film is 0.0805 Mpa. The maximum pressure of the film is increased by nearly 19.25 %. Compared with Al@PVDF film, the ignition delay time of Al/AP@PVDF film is shortened by 45 ms, and the light intensity is increased by nearly 93.39 %. However, excessive AP content adversely impacted film formation efficiency, leading to the deterioration of various properties. Therefore, an optimal AP content of approximately 15 % in Al/AP@PVDF system was finally identified.

Research on Multi-Mode Variable Parameter Intelligent Shift Control Method of Loader Based on RBF Network

The loader is one of the most widely used pieces of engineering machinery in the world for soil transportation, loading and unloading materials, and low-intensity shovel digging operations in harsh and complex operating conditions; it requires very frequent shifting and has other challenging characteristics. In order to realize automatic frequent shifting, we need to better design the shifting rules in the shifting process, improve the shifting quality and working efficiency, and solve the key engineering problems of energy saving and high efficiency in the shifting process of loaders. In this paper, a 7-ton wheel loader is taken as the research object, the loader shoveling process of the four operating modes is analyzed, and a multi-mode variable parameter shift law is designed. Aiming at the complicated and nonlinear characteristics of the power transmission system of the loader, an intelligent shift control method based on an RBF neural network is proposed. Finally, the simulation test and the clutch shift oil pressure test are carried out. From the test results, the clutch test oil pressure curve obviously shows a four-stage upward trend during shifting, and the buffering effect is obvious. The designed multi-mode variable-parameter intelligent shift law of the loader is reasonable and feasible, and the shift recognition rate reaches 97.92%, which provides theoretical support for the realization of intelligent automatic speed change control of the loader, and it certainly has engineering value.

Long-Term Effects of Tea Consumption Habits on Cardiovascular Performance of Adolescent Population: An Observational Study of Adolescent Community in Jakarta, Indonesia

Background: Tea is a popular drink that is widely consumed in Indonesia. Some studies show the potential benefits of tea on cardiovascular health, but evidence regarding long-term effects in adolescents is limited. This study aims to evaluate the relationship between tea consumption habits and cardiovascular performance in the adolescent population in Jakarta. Methods: This prospective observational cohort study involved 1,500 adolescents aged 15-18 years in Jakarta. Data on tea consumption habits was collected through a structured questionnaire, while cardiovascular performance was measured through blood pressure tests, body mass index (BMI), and treadmill tests. Logistic regression and Cox proportional hazards analyzes were used to identify the association between habitual tea consumption and cardiovascular events over a 5-year period. Results: The results showed that regular tea consumption (≥3 cups/week) was associated with a reduced risk of hypertension (OR 0.65; 95% CI 0.48-0.88) and an increase in cardiovascular functional capacity as measured by treadmill testing (HR 0 .72; 95% CI 0.55-0.94). Conclusion: The habit of regular tea consumption among adolescents in Jakarta is associated with a reduced risk of hypertension and improved cardiovascular performance. Further research is needed to confirm these findings and explore the mechanisms underlying tea's protective effects.

Research on Thread Seal Failure Mechanism of Casing Hanger in Shale Gas Wells and Prevention Measures

The strength and sealing failure of the connecting thread of the casing head mandrel hanger causes huge economic losses. One of the major challenges is the thread seal failure mechanism of the casing hanger in the wellhead during pressure testing in shale gas wells. In order to analyze the failure causes of connecting threads and put forward improvement measures, a typical case of a well accompanied by a hanger seal failure is analyzed in this paper, and a series of material tests are carried out. The microstructure and mechanical properties of casing materials and hanger materials could meet the field requirements. It is concluded that both the hanger material and casing material are characterized with significant ductile fracture. A three-dimensional model of the hanger and casing system is established, and the mechanical behavior is calculated for the connecting thread under different working conditions. The results showed that the connection degree of the hanger–casing is insufficient at the torque recommended by the manufacturer because of the difference in wall thickness between the box thread of the hanger and the box thread of the joint according to the connection degree of the coupling casing. It is seen that the high contact pressure ring of zone three on the sealing surface plays an effective sealing role under the manufacturer’s recommended torque (20,465 N·m). Finally, when the torque is increased by 25%, the maximum contact pressure between the pin thread of the casing and the box thread of the hanger can fully meet the internal pressure from the wellbore pressure test and the internal pressure strength required for subsequent operations.

On the application of reduced pressure test for the prediction of ductility of 46000 alloy: Role of pore's morphology and distribution

Bifilms have been proposed to be critical for forming casting defects. The reduced pressure test (RPT) and bifilm index (BI) have been widely studied and used in industry for melt quality assessment. However, the BI remains challenged in predicting the mechanical properties. This work investigated the usage of RPT for elongation prediction by analyzing the melt in two foundries. The results showed that the BI could be valid when the bifilms exist as fully inflated pores. In reality, bifilms present as pores with various morphology and distribution, generating local stress concentrations under tension. Consequently, the parameter areaeff, which considers the pores’ morphology and distribution, was proposed, and the resultant feff showed a good correlation with the elongation of the castings. These results guide the foundry to predict the elongation of the final castings and give directions for further research on the bifilm defects.

Biomechanical variations in patients with flatfoot deformity: Impact of gender, age, and BMI on foot kinetics and kinematics

BackgroundFlatfoot is considered by the collapse of the foot arch, altered biomechanics and impacting functional abilities. The biomechanical gait alteration of foot kinematics and kinetics in individuals with flatfoot, based on gender, age and Body mass index (BMI) in each cohort is unclear. This study explores how gender, age, and body mass index (BMI) impact distinct foot biomechanical characteristics, including ankle joint angle (Jc°), Ground force reaction angle (GFR°), Achilles tendon force (T), Ankle joint force (Jc) and vertical ground reaction force (VGRF) during the gait stance phase, in flatfoot versus normal-foot individuals on Indian Population. MethodA foot pressure test and sagittal plane motion analysis were performed on 142 individuals with normal-foot arches and 102 with flatfoot, stratified by gender, age, and BMI. Calculations of the magnitude and direction of forces in ankle joint equilibrants relied on inverse dynamic analysis, vertical ground force reaction and mapping motion data of the gait stance phases. ResultIn the midstance phase, females with high BMI (HBMI) in the middle and older age group (p = 0.029 and p = 0.014), and males with HBMI in the older age group (p = 0.039) demonstrate significantly higher VGRF. Females and males with HBMI in middle and older age groups, along with males with normal BMI in the older age cohort, show positive and negative ranges of GFR°, indicating gait instability. In the push-off phase, females with HBMI in a middle-aged group exhibit significantly lower TandJc (p = 0.023 and p = 0.026) respectively. ConclusionThe biomechanical issues in individuals with flatfoot, while accounting for the influence of gender, age and BMI, are crucial for tailored interventions and precise solutions to biomechanical issues, thereby enhancing foot function and reducing discomfort.

Fabrication and mechanical characterization of near field electrospun bioresorbable vascular grafts with fibrous architecture mimicking the arterial extracellular matrix

Cardiovascular disease, arteriosclerosis, is characterized by the thickening of blood vessel (arteries) walls restricting blood flow and is a global health problem. One treatment option is a surgical procedure utilizing an autologous or synthetic vascular graft to bypass or replace the diseased arterial segment. The goal of this study was to fabricate and mechanically characterize near field electrospun bioresorbable vascular grafts with a fibrous architecture that mimics the arterial extracellular matrix. Polydioxanone vascular constructs with circumferential fiber alignment angles of 15°/75° and 30°/60° (0° representing circumferential fiber alignment) were fabricated using a custom built near-field electrospinning (NFES) system. The vascular construct mechanical properties were compared to the saphenous vein (SV) and internal mammary artery (IMA) through longitudinal and circumferential uniaxial mechanical testing, suture retention, and burst pressure evaluations. The results demonstrated that the 15°/75° templates were closest to mimicking the native vessel target properties as compared to the 30°/60°; however, neither of the vascular template designs achieved or exceeded all the target values. For the ultimate tensile strength, both the constructs met the SV value on the circumferential axis (2.61 MPa) and the IMA value on the longitudinal axis (4.3 MPa). In terms of suture retention, the 15°/75° template was the only construct that was in the IMA and SV targeted range of 138–200 gf. Finally, the burst pressure testing results indicated that neither of the vascular constructs achieved the level of the SV or IMA (1600–3196 mmHg), however, the 15° constructs were within the lower error of the SV. In conclusion, with further design modifications, NFES constructs have demonstrated promise as small-diameter vascular grafts by mimicking native arterial architecture and mechanical properties.

Could headache in children be a biomarker for dyslipidemia?

Here we present the patients whose body mass index is in the normal range and who visited with the complaint of headache. The differences in lipid profile in this group compared to healthy children and the risk factors that may be associated with this were investigated. 195 patients who applied to the Pediatric Neurology outpatient clinic with headache complaints between April 2021 and October 2022 were retrospectively examined. 201 healthy children were included as the control group. The gender, age, headache type, lipid profile blood test after at least 8h of fasting [total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglyceride (TG), and TG/HDL ratio], and body mass index (BMI) were recorded. Those patients who had a BMI range of 18.5-24.9kg/m2 were included in the study. The study group had 195 patients; 118 girls (60.5%). The average age was 12,57 ± 3,48years, and 114 patients (58.5%) had tension-type headaches and 81 (41.5%) had migraine-type headaches. There was no significant difference in age and gender between the two groups. Blood pressure, folate, and thyroid function tests were normal. In the lipid profile, a significant difference was observed between total cholesterol, LDL, HDL, and TG in the study group compared to the control group (p < 0.05). However, there was no difference in the TG/HDL ratio between those two groups. No significant statistical difference was observed in the lipid profile and other laboratory findings between headache types. In children presenting with headache complaints, which can be both worrying for families and cause significant loss of functionality, it is detectable (obviously) that headache is an important marker for dyslipidemia; even if BMI is in a normal range. The lipid profile should be seen both to control the complaint with an appropriate diet and to observe the risk of future atherosclerotic processes.

Optimization of pre-grouting construction and evaluation of grouting effect in a deeply buried silt-filled shield tunnel

Controlling strata deformation during shield tunneling beneath unconsolidated soil layers poses a significant challenge in engineering construction. Limited research exists on optimizing pre-grouting mechanisms for shield tunnels in unconsolidated soil layers and controlling strata deformation. Therefore, conducting on-site optimization experiments for pre-grouting is crucial for controlling strata deformation. The paper employs crushed stone aggregate as a basis for modifying the shield jacket material. The primary method of verifying grout strength involves direct detection of foundation bearing capacity using a heavy-duty probe inside the tunnel. The feasibility of the comprehensive evaluation scheme is further confirmed through a combination of multi-point core sampling, five-point water pressure tests, and on-site shield monitoring data. The research results indicate that this technology effectively enhances the stability of deep-buried weak strata. By improving the physical and mechanical properties of backfill soil through a combination of crushed stone-cement slurry-soil skeleton, the self-stabilizing ability of surrounding rock is enhanced, and strata deformation is controlled. Additionally, a set of pre-grouting reinforcement and evaluation techniques suitable for deep-buried weak strata is proposed, providing valuable references for similar projects.

Failure Analysis of CRDINiCr Butterfly Valves for Nuclear Power Plant Applications

Corrosion-resistant iron with nickel and chromium (CRDINiCr) is often used in butterfly valves for flow control at nuclear power plants, where resistance to corrosion, oxidation, and wear is significant. In this study, a failure analysis of a CRDINiCr alloy butterfly valve was performed by combining morphology characterization and in situ elemental composition analysis of failure of various regions of the valve. Based on the testing and analysis conducted in this study, it was determined that the inspected valve body material exhibited several defects, including poor graphitization, porosity, and the presence of eutectic carbides. These imperfections compromised the required plasticity criteria, resulting in significant embrittlement of the material. Therefore, under the impact stresses applied during the pressure testing, these vulnerabilities facilitated rapid crack initiation and propagation. The presence of such defects significantly compromised the material’s resistance to fracture under dynamic loading conditions, underscoring the critical importance of stringent quality control in the production of such materials to ensure their reliability and performance in operational settings at nuclear power plants.

Leakage detection applied to the Da Hedong Reservoir dam (China) based on the flow-field fitting method

Detecting leakage in concrete gravity dams presents a formidable challenge. The flow-field fitting (FFF) method is used to identify leaks in China’s Da Hedong Reservoir dam. We develop vertical- and horizontal-gradient approaches based on the transmitted signal electrical field. A plastic frame is developed to allow the probe to measure horizontal gradients. We determine the exact location of leaks at the reservoir’s bottom and upstream face, respectively, assuming that current leakages are located in hydraulic leakage zones. Numerical experiments and water pressure tests reveal that the conductive silt layer beneath the reservoir can lower the response of the potential values at the leakage inlet, and the effect of the silt layer should be considered and not ignored when interpreting measured data. In addition, with regard to the principle of superposition, the contribution associated with metal pipes in the dam body can be roughly determined by subtracting it from the original potential field data, thereby aiding in locating leaks around the metal pipes. In addition, the FFF measurements from the reservoir’s bottom also confirm the position of existing faults in the substratum at the reservoir site. Last, the results of the FFF method are tested against supporting evidence, such as ground penetrating radar and water pressure tests. In conclusion, these independent data confirm the effectiveness of the FFF method for leakage localization in the concrete gravity dam.

Artificial neural network evaluation of concrete performance exposed to elevated temperature with destructive–non-destructive tests

In this study, it is aimed to predict the performance of concretes obtained by using supplementary cementitious materials (SCM) before and after high temperature using artificial neural network. Thus, in addition to contributing to sustainable development and circular economy by using waste materials in concrete production, predicting concrete strength using artificial neural network without the need for experimental studies will provide a great advantage in practice. In addition, it will also contribute to the literature in terms of determining the optimum amount of metakaolin to be used with fly ash in concrete production. Metakaolin, silica fume and fly ash were used as SCM in different proportions in concrete mixes. Accordingly, a total of 22 concrete series were prepared, one of which was the control series. Porosity, ultrasonic pulse velocity, pressure and tensile strength tests were applied to the series at the end of 7th, 28th and 90th curing periods before high temperature. In order to determine the strength losses after elevated temperature, porosity and compressive strength tests were applied at temperatures of 400, 600 and 800 °C. Mineral additive series showed positive mechanical properties up to 20%. However, it has been observed that the use of fly ash after a certain rate causes a decrease in strength. After elevated temperature, strength loss was observed in all series due to the increase in temperature, while it was observed that the rate of being affected by elevated temperature decreased as the percentage of metakaolin increased. Optimum mineral additive usage percentages were determined as 10% fly ash and 15% metakaolin. On the other hand, the use of mineral additives above the optimum level caused the performance of the concrete to decrease. Then, the concrete compression strengths obtained at 7th, 28th, and 90th days and at 400, 600 and 800 °C temperatures are taken as the outputs of the ANN. The artificial neural network provided the closest results to experimental data. Moreover, to prove the predictive performance of ANN, a comparative analysis was made with GPR, SVM and LR and the smallest value of the RMSE value is obtained with the ANN model. Finally, a fivefold cross-validation criteria was used to objectively present the performance of the model.