Journal articles on the topic 'Concrete construction – Mathematical models'
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1
Zayed, Tarek M., and Ibrahim A. Nosair. "Cost management for concrete batch plant using stochastic mathematical models." Canadian Journal of Civil Engineering 33, no. 8 (August 1, 2006): 1065–74. http://dx.doi.org/10.1139/l06-051.
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Assessing productivity, cost, and delays are essential to manage any construction operation, particularly the concrete batch plant (CBP) operation. This paper focuses on assessing the above-mentioned items for the CBP using stochastic mathematical models. It aims at (i) identifying the potential sources of delay in the CBP operation; (ii) assessing their influence on production, efficiency, time, and cost; and (iii) determining each factor share in inflating the CBP concrete unit expense. Stochastic mathematical models were designed to accomplish the aforementioned objectives. Data were collected from five CBP sites in Indiana, USA, to implement and verify the designed models. Results show that delays due to management conditions have the highest probability of occurrence (0.43), expected value of delay percent (62.54% out of total delays), and relative delay percent. The expected value of efficiency for all plants is 86.53%; however, the average total expense is US$15.56/m3 (all currency are in US$). In addition, the expected value of effective expenses (EE) is $18.03/m3, resulting in extra expenses (XE) of $2.47/m3. This research is relevant to both industry practitioners and researchers. It develops models to determine the effect of delays on concrete unit cost. They are also beneficial to the CBP management.Key words: concrete batch plant, delays, management conditions, cost models, cost management, stochastic mathematical models.
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Folic, Radomir, Damir Zenunovic, and Nesib Residbegovic. "Strength of connections in precast concrete structures." Facta universitatis - series: Architecture and Civil Engineering 9, no. 2 (2011): 241–59. http://dx.doi.org/10.2298/fuace1102241f.
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The available experimental and numerical results of many studies of behavior of reinforced concrete connections for different stages of loading, up to fracture loading, are presented and analyzed in this paper. The problem of beam-column connection (or plate-wall connection) in prefabricated monolithic structures is emphasized. Fracture mechanisms of RC structures, the theoretical basis for their analysis, and the use of fracture mechanics in RC structures were also considered, as well as the mathematical models of prefabricated connections. In order to formulate an adequate mathematical model for calculating the connections, the dominant parameters influencing the behaviour of these connections were analyzed. A failure model for the prefabricated wall - monolithic RC plate connection was formulated. In building the model, the results of implemented experimental and numerical research of prefabricated connection in the MMS system from 2007 were used. Experiences with the implementation of the aforementioned construction system in structures in Tuzla, in the 1980's last century, were additionally used. The proposed mathematical models provide a sufficiently accurate failure assessment of prefabricated reinforced concrete connections.
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Murashkin, Vasily G. "Features of Nonlinear Deformation of Concrete." Scientific journal “ACADEMIA. ARCHITECTURE AND CONSTRUCTION”, no. 1 (March 18, 2019): 128–32. http://dx.doi.org/10.22337/2077-9038-2019-1-128-132.
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In most studies, when the problem of determining a nonlinear model of deformation of structural concrete in normal environment, or experienced a variety of destructive (aggressive, temperature, etc.) exposure, using individual mathematical apparatus and software. The main criterion in these works for the construction of the deformation model of concrete was a unique relationship "strength - modulus of elasticity". Apply the developed model for another type of concrete or experienced a destructive impact was erroneous. However, not all features of concrete deformation in the construction of models were taken into account. In particular, the gentle nature of deformation in the initial stage of loading was not taken into account. Similarly, models of nonlinear deformation of concrete in normative materials of different countries are constructed. Especially there are problems in the inspection of structures operated for along time. It is not rational to create individual models based on the algorithm created earlier. In recent studies, a number of works have noted the need to take into account the features of the initial stage ofloading of concrete and the fact that concrete from the beginning ofloading has macro and micro cracks and structural defects. But even in these works the possibility of creating a nonlinear deformation model based on experimentally obtained data when testing prototypes of generalized model was not considered. This article discusses the possibility of constructing a concrete extracted from the structure. The possibility of replacing the individual deformation models with the proposed one is shown. In the generalized model of deformation "strength and modulus of elasticity" may not coincide with the normative characteristics and it can serve as a basis for determining the stress state in the survey of operated structures and, if necessary, for the design of new ones.
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Vojtasik, Karel, Eva Hrubesova, Marek Mohyla, and Lukáš Duris. "Design and Evaluation of a Subterranean Work Lining from Layers of Shotcrete and Steel Arch." Advanced Materials Research 1020 (October 2014): 347–50. http://dx.doi.org/10.4028/www.scientific.net/amr.1020.347.
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A steel concrete lining is today the common ground massive retaining structure implemented shortly after the excavation of an opening. The constituent elements of the steel concrete lining are layers of shotcrete and steel arch frames. This simple structure has many unique features which set it apart from the conventional reinforced concrete constructions. Without simplification these features doesn’t allow to carry out design and evaluation of steel concrete lining by relevant design and evaluation methods convenient to the conventional reinforced concrete constructions. The main differences are construction process, yielding curve of structure and determination of external load. In the case of a steel concrete lining its external load is product of mutual work of both the ground massive and the lining. The value of load depends on the yielding curves of the lining and the ground massive. The yielding curve of a ground massive is objective and conditioned on strength strain properties of ground massive and primary stress state. The yielding curve of a steel concrete lining relates lining design specification. The process of construction affects the value of load too. The article analyzes the steel concrete lining focusing the influence of lining design parameters on its yielding curve. It looks for a way to control the ground massive behavior and as well as to engage it more in an effort with lining to stabilize subterranean work. The themes of the analysis are: static and deformation parameters of the cross-section of the steel concrete lining with regard to the construction stage and dependency of hardening shotcrete; interaction between of steel concrete lining and ground massive based on yielding curves; assessment of a stress state across the steel concrete lining section in the steel concrete lining constituent elements. The analysis is carried out on mathematical models that combine analytical and numerical methods.
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Ouahmane, Issam, Rachid El Alaiji, Mohammed Sallaou, and Larbi Lasri. "General Mathematical Model for Analysing the Bending Behaviour of Rectangular Concrete Beams with Steel, Fibre-Reinforced Polymers (FRP) and Hybrid FRP–Steel Reinforcements." Buildings 12, no. 11 (November 12, 2022): 1964. http://dx.doi.org/10.3390/buildings12111964.
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The design guidelines available in building codes for steel and fibre reinforced polymer (FRP) reinforced concrete (RC) beams have been developed on the basis of empirical models. While these models are successfully used for practical purposes, they require continuous improvements with more experimental data. This paper aims to develop a general mathematical model derived from the intrinsic material properties of concrete and certain reinforcements to analyse the bending behaviour of reinforced concrete beams. The proposed model takes into account the effects of non-linearity and ductility on the real behaviour of concrete under compression as well as the concrete tension stiffening. The model focused on analysing the flexural behaviour of rectangular steel, FRP and hybrid FRP–steel RC beams, using the moment–curvature relationship. A general static equilibrium equation was developed and mathematically solved with precise methods to establish a moment–curvature relationship. The effective flexural stiffness (EFS) is therefore calculated by the slope of the moment–curvature diagram, and then the load–deflection response is immediately deduced according to the loading conditions. The present model results were compared with numerous test data reported by various researchers. The comparisons reveal a good accuracy for predicting the EFS and load–deflection response for either steel, FRP, and hybrid reinforced concrete beams, with an error average less than 10%.
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Velichkin, Vladimir, Vladimir Zavyalov, Elena Solodovnikova, and Elena Filippova. "Mathematical descriptions of heat-mass-exchange processes in construction industry at control automation." E3S Web of Conferences 97 (2019): 06021. http://dx.doi.org/10.1051/e3sconf/20199706021.
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The paper covers matters arising in building mathematical model of processes at thermal treatment of construction materials. On the basis of analysis of heat energy and moisture flows in intermittent steam chamber and continuous tunnel drying chamber, analytic and structure models of heat-mass-exchange processes in processing vessels are drawn. The structural model of heat-mass-exchange processes allowed to evaluate the relationship of heat energy and moisture flows at heat treatment processes for gypsum and reinforced-concrete articles. The resulting system of interrelated differential equations is based on a structural model. Analytical studies showed that the considering heat treatment units are characterized by non-stationary, non-linear, stochastic and distributed technological parameters. An experimental study of technological devices has shown that in a limited time range, the processes of heat-mass-exchange can be characterized by a system of linear differential equations with constant coefficients with sufficient accuracy for practice. Acceptable allowances and simplifying assumptions at analytical description of heat-mass-exchange processes in processing vessels are considered. As a result of performed research, various mathematical forms (differential equation system, matrix and operator forms) of mathematical models of processing vessels are obtained. The built mathematical models may be applied for constructing the processing vessels with preset dynamic properties, as well for control-system designing by those vessels.
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Ye, Zheng Mao, Lian Cong Zheng, Li Hua Wan, and Xin Cheng. "Application of Second Law of Fick in NaCl Attack of Sulphoaluminate Cement." Advanced Materials Research 306-307 (August 2011): 1038–41. http://dx.doi.org/10.4028/www.scientific.net/amr.306-307.1038.
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The standard diffusion calculating model is one of the models widely used to predict the concrete construction life in chloride environment. According to test results, the surface concentration and the initial concentration of chloride ion on sulphoaluminate cement sample was analyzed by mathematical method. Life prediction model in chloride environment was built. According to the model, the sulphoaluminate cement construction life will be 51.5 years when the thickness of cement protective layer is 40mm.
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Kovačević, Miljan, Nenad Ivanišević, Dragan Stević, Ljiljana Milić Marković, Borko Bulajić, Ljubo Marković, and Nikola Gvozdović. "Decision-Support System for Estimating Resource Consumption in Bridge Construction Based on Machine Learning." Axioms 12, no. 1 (December 24, 2022): 19. http://dx.doi.org/10.3390/axioms12010019.
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The paper presents and analyzes the state-of-the-art machine learning techniques that can be applied as a decision-support system in the estimation of resource consumption in the construction of reinforced concrete and prestressed concrete road bridges. The formed database on the consumption of concrete in the construction of bridges, along with their project characteristics, was the basis for the formation of the assessment model. The models were built using information from 181 reinforced concrete bridges in the eastern and southern branches of Corridor X in Serbia, with a value of more than 100 million euros. The application of artificial neural network models (ANNs), models based on regression trees (RTs), models based on support vector machines (SVM), and Gaussian processes regression (GPR) were analyzed. The accuracy of each model is determined by multi-criterion evaluation against four accuracy criteria root mean square error (RMSE), mean absolute error (MAE), Pearson’s linear correlation coefficient (R), and mean absolute percentage error (MAPE). According to all established criteria, the model based on GPR demonstrated the greatest accuracy in calculating the concrete consumption of bridges. According to the study, using automatic relevance determination (ARD) covariance functions results in the most accurate and optimal models and also makes it possible to see how important each input variable is to the model’s accuracy.
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RYAZANOVA, Galina N., Irina O. KOROTYCH, and Anastasia Yu PROKOPYEVA. "MATHEMATICAL AND TECHNOLOGICAL MODELING FOR SOLVING OF PROBLEMS OF THE TECHNOLOGY OF CONSTRUCTION OF ENVELOPES FROM NO-FINE EXPANDED-CLAY CONCRETE IN A PERMANENT FORM." Urban construction and architecture 7, no. 1 (March 15, 2017): 30–35. http://dx.doi.org/10.17673/vestnik.2017.01.5.
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The article views the problems of construction of envelope structures from no-fi ne expanded-clay concrete in a permanent form made from cement-bonded boards and due to the complexity of the technological problems associated with the processes of mixing and laying of light concrete mixture into the form that are solved by methods of mathematical modeling. The main technological challenges in the construction of structures made of no-fi ne expanded-clay concrete are considered. Specifi c volumes of aggregates and cement glue and their mass are theoretically and numerically determined. Control parameters and functions are studied to calculate the saturation depth of the aggregate grains. The links of relative depth impregnation dR / R of eff ective porosity of diff erent structures are derived. The conclusions about further implementation of the models and their research are made.
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Dvorkin, Leonid, and Vitalij Marchuk. "Dry mixes on the basis of reactive-powder concrete." Zastita materijala 63, no. 3 (2022): 309–17. http://dx.doi.org/10.5937/zasmat2203309d.
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This article presents the results of experimental studies of mortars based on dry mixes using reactive-powder concrete (RPC). This type of concrete can serve not only as the structural material in the construction of buildings and structures, but also as a semi-finished product for obtaining dry building mixes for various purposes. Redispersed polymer powder as well as fly ash according to the results of the conducted research can be used as additional components for the preparation of various dry building mixes. For development of compositions of dry mixes used the statistical models received by means of mathematical planning of experiments.
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Habib, A., and U. Yildirim. "Simplified modeling of rubberized concrete properties using multivariable regression analysis." Materiales de Construcción 72, no. 347 (September 5, 2022): e289. http://dx.doi.org/10.3989/mc.2022.13621.
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The studies on rubberized concrete have increased dramatically over the last few years due to being an environmentally friendly material with enhanced vibration behavior and energy dissipation capabilities. Nevertheless, multiple resources in the literature have reported reductions in its mechanical properties directly proportional to the rubber content. Over the last few years, various mathematical models have been proposed to estimate rubberized concrete properties using artificial intelligence, machine learning, and fuzzy logic-based methods. However, these models are relatively complicated and require higher computation efforts than multivariable regression ones when it comes to the daily usage of practicing engineers. Additionally, most of the study has mainly focused on the compressive strength of rubberized concrete and rarely went into more details considering other properties and sample sizes. Therefore, this study focuses on developing simple yet accurate rubberized concrete multivariable regression models that can be generalized for various mixtures of rubberized concrete considering different sample sizes.
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Nguyen, N. T., D. J. Oehlers, and M. A. Bradford. "Models for the Flexural Peeling of Angle Plates Adhesively Bonded to R-C Beams." Advances in Structural Engineering 1, no. 4 (October 1998): 287–300. http://dx.doi.org/10.1177/136943329800100405.
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The strength and stiffness of existing reinforced concrete beams may be enhanced by adhesively bonding angle section members to the soffit/side edges of reinforced concrete (RC) beams. This retrofitting is extremely important in improving the seismic performance of under reinforced RC beams which may suffer ductility problems in earthquakes, or whose strength has deteriorated due to unfavourable environmental factors. This paper develops generic mathematical models for simulating the debonding of angle plates glued to the edges of RC beams as a result of flexural peeling. It is shown that to achieve an accurate model the derivations are quite complex, but the experimental calibration renders the presentation of the model in a simple format. The models have been validated with experimental results.
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Konopatskiy, E. V., I. V. Seleznev, and A. A. Bezditnyi. "The use of interpolation methods for modelling multifactor processes based on an experiment planning matrix." Journal of Physics: Conference Series 2182, no. 1 (March 1, 2022): 012005. http://dx.doi.org/10.1088/1742-6596/2182/1/012005.
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Abstract This article is dedicated to the development of experimental data processing tools based on the geometric theory of multidimensional interpolation. At the same time, a scientific problem was solved, which is dedicated to the analytical determination of models of multifactor processes while maintaining the existing approach to experiment planning This makes it possible not only to use interpolation methods for the mathematical description of new experiments, but also to use the experimental data obtained earlier to improve their mathematical interpretation. The paper provides two examples that confirm the effectiveness of the proposed approach to constructing models of multivariate processes using multivariate interpolation methods. The first of the above examples contains two geometric models of the stress-strain state of metal polyhedral bent struts, which are presented in the form of ruled response hypersurfaces passing through 8 predetermined points in the 4-dimensional space. The second one is dedicated to the construction of a 2-factor process process using a 2- parameter parabolic geometric interpolant with subsequent optimization by methods of mathematical analysis of a function of two variables. As a result, the optimization of the aerated concrete manufacturing process was carried out to achieve the maximum values of the ultimate strength in compression after heat and moisture treatment.
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Babich, Volodymyr, Olena Polianovska, and Igor Shvets. "THE DETERMINATION OF PARAMETERS OF COMBINED REINFORCEMENT OF STRETCHED AND BENDING REINFORCED CONCRETE ELEMENTS WITH THE SPECIFIC CRACK RESISTANCE." Collected scientific works of Ukrainian State University of Railway Transport, no. 198 (May 12, 2022): 40–49. http://dx.doi.org/10.18664/1994-7852.198.2021.256536.
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Recently, there has been an increase in the use of reinforced concrete structures withcombined reinforcement in construction, which makes it possible to increase the resistance of suchstructures to deformation and cracking. Dispersed reinforced concrete was used to cover roads, flooring in industrial buildings, the manufacture of curbs and more. For the construction of publicand industrial buildings, the use of combined reinforced structures has not been widely used, as noperfect method of their calculation has been developed.Combined reinforcement structures include concrete structures that are reinforced with steelrods and steel fiber, which is randomly arranged in the mass of concrete. The strength of reinforcedconcrete depends on such factors as: the strength of concrete, reinforcement with rod reinforcement,the type of fiber and its characteristics, the volume of fiber per unit volume of concrete, the size ofthe cross section of the elements. These factors affect the tensile strength of reinforced concrete bothdirectly and by their interaction. Therefore, determining the effective parameters of dispersedconcrete reinforcement is a complex multivariate task, its solution is proposed to be achieved byperforming mathematically planned experiments.When choosing the parameters of dispersed reinforcement of centrally stretched and bendingreinforced concrete elements (lower truss belt, arch tightening, cylindrical tank wall, beams, slabs),it is advisable to choose the strength of concrete fck, fiber length lf and volume dispersion coefficient.The optimal choice of values of these parameters is proposed to be performed using quadraticregression equations, which are based on the results of three-factor three-level mathematicallyplanned experiments, which are based on the matrix of the Box-Behnken plan.The obtained mathematical models make it possible to analyze the influence of dispersereinforcement parameters on crack formation forces in combined reinforced concrete elements andto determine their optimal values. The use of combined reinforcement allows increasing the crackresistance of reinforced concrete elements in two or more times.
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Kharun, Makhmud, Sergey Klyuev, Dmitry Koroteev, Paschal C. Chiadighikaobi, Roman Fediuk, Andrej Olisov, Nikolai Vatin, and Nataliya Alfimova. "Heat Treatment of Basalt Fiber Reinforced Expanded Clay Concrete with Increased Strength for Cast-In-Situ Construction." Fibers 8, no. 11 (November 2, 2020): 67. http://dx.doi.org/10.3390/fib8110067.
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Expanded clay concrete (ECC) is a promising structural material for buildings due to its light weight and heat- and sound-insulating properties. Adding basalt fibers (BFs) in ECC reduces its brittleness and enhances its mechanical properties. The heat treatment (HT) of BF-reinforced ECC can significantly accelerate the strength growth during cast-in-situ construction, which allows the reduction of the turnover of the formwork and the construction period, as well as leading to lower construction costs. This paper presents an HT technology for load-bearing structures, containing a BF-reinforced ECC mix and using infrared rays for cast-in-situ construction. The issue of the strength growth of BF-reinforced ECC during HT has been studied. Microsilica and fly ash were added to the ECC mix to obtain a compressive strength of more than 20 MPa. Four different mixes of ECC with chopped BFs in the ratios of 1:0, 1:0.0045, 1:0.009 and 1:0.012 by weight of cement were studied. Test specimens were heated by infrared rays for 7, 9, 11, 13, 16 and 24 h. Then, the heat-treated specimens were tested for compressive strength after 0.5, 4, 12 and 24 h cooling periods. The analysis and evaluation of the experimental data were carried out based on probability theory and mathematical statistics. Mathematical models are proposed for forecasting the strength growth of BF-reinforced ECC during cast-in-situ construction.
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Amin, Muhammad Nasir, Kaffayatullah Khan, Fahid Aslam, Muhammad Izhar Shah, Muhammad Faisal Javed, Muhammad Ali Musarat, and Kseniia Usanova. "Multigene Expression Programming Based Forecasting the Hardened Properties of Sustainable Bagasse Ash Concrete." Materials 14, no. 19 (September 28, 2021): 5659. http://dx.doi.org/10.3390/ma14195659.
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The application of multiphysics models and soft computing techniques is gaining enormous attention in the construction sector due to the development of various types of concrete. In this research, an improved form of supervised machine learning, i.e., multigene expression programming (MEP), has been used to propose models for the compressive strength (fc′), splitting tensile strength (fSTS), and flexural strength (fFS) of sustainable bagasse ash concrete (BAC). The training and testing of the proposed models have been accomplished by developing a reliable and comprehensive database from published literature. Concrete specimens with varying proportions of sugarcane bagasse ash (BA), as a partial replacement of cement, were prepared, and the developed models were validated by utilizing the results obtained from the tested BAC. Different statistical tests evaluated the accurateness of the models, and the results were cross-validated employing a k-fold algorithm. The modeling results achieve correlation coefficient (R) and Nash-Sutcliffe efficiency (NSE) above 0.8 each with relative root mean squared error (RRMSE) and objective function (OF) less than 10 and 0.2, respectively. The MEP model leads in providing reliable mathematical expression for the estimation of fc′, fSTS and fFS of BA concrete, which can reduce the experimental workload in assessing the strength properties. The study’s findings indicated that MEP-based modeling integrated with experimental testing of BA concrete and further cross-validation is effective in predicting the strength parameters of BA concrete.
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Rahman, Muhammad Ekhlasur, Timothy Zhi Hong Ting, Hieng Ho Lau, Brabha Nagaratnam, and Keerthan Poologanathan. "Behaviour of Lightweight Concrete Wall Panel under Axial Loading: Experimental and Numerical Investigation toward Sustainability in Construction Industry." Buildings 11, no. 12 (December 6, 2021): 620. http://dx.doi.org/10.3390/buildings11120620.
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Awareness of sustainability in construction has led to the utilization of waste material such as oil palm shell (OPS) in concrete production. The feasibility of OPS as alternative aggregates in concrete has been widely studied at the material level. Meanwhile, nonlinear concrete material properties are not taken into account in the conventional concrete wall design equations, resulting in underestimation of lightweight concrete’s wall axial capacity. Against these sustainability and technical contexts, this research investigated the buckling behavior of OPS-based lightweight self-compacting concrete (LWSCC) wall. Failure mode, load-deflection responses, and ultimate strength were assessed experimentally. Numerical models have been developed and validated against experimental results. Parametric studies were conducted to study the influence of parameters like slenderness ratio, eccentricity, compressive strength, and elastic modulus. The results showed that the axial strength of concrete wall was very much dependent on these parameters. A generalized semi-empirical design equation, based on equivalent concrete stress block and modified by mathematical regression, has been proposed. The ratio of average calculated results to test results of the proposed equation, when compared to ACI 318, AS 3600, and Eurocode 2 equations, are respectively improved from 0.36, 0.31, and 0.42 to 0.97. This research demonstrates that OPS-based LWSCC concrete can be used for structural axial components and that the equation developed can serve a good guideline for its design, which could encourage automation and promote sustainability in the construction industry.
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Niyakovski, Alexander M., Uladzimir N. Ramaniuk, Аleksandr N. Chychko, and Yury V. Yatskevich. "Unsteady model of the hydration process of a reinforced concrete product at software-controlled heating." Doklady of the National Academy of Sciences of Belarus 63, no. 4 (September 13, 2019): 496–505. http://dx.doi.org/10.29235/1561-8323-2019-63-4-496-505.
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The development of mathematical models for design of the thermal technology equipment intended for accelerated hydration of concrete products is an urgent task of industrial heat power engineering. The introduction of mathematical modeling methods can reduce the time and the resources spent for the development of technological regimes that reduce energy consumption in the production of building structures and, ultimately, in the construction of buildings and structures for various purposes. There is not yet a generally accepted mathematical model of thermal processes occurring in thermal technological installations in the case of accelerated hardening of a three-dimensional concrete object. The purpose of this work is to develop an unsteady model of the concrete hydration process applied to a symmetrical three-dimensional reinforced concrete product at software-controlled heating. By using the numerical finite-volume method in the case of a 0.3 × 0.3 ×0.3 mcube, a three-dimensional feld of hydration in a concrete object at a given operation mode of a heater is calculated. The following heating mode was used: “heating–maintaining at a constant temperature–cooling”. The dependences of a temperature difference between reinforced and non-reinforced cubic products on the hardening time at the corresponding space points in the direction from the surface to the center of the product have been obtained. By the example of the numerical simulation results, it is shown that the evolution of the hydration degree at these points during the hardening of non-reinforced concrete differs from the hardening of reinforced concrete. The time dependences of heat treatment of a rate of temperature change and the hydration coefficient at the selected points of a product are presented. The obtained results are analyzed.
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Rajczyk, Jarosław. "Modelling the Dynamic Load Process in the Building Technology Process." Applied Mechanics and Materials 405-408 (September 2013): 652–56. http://dx.doi.org/10.4028/www.scientific.net/amm.405-408.652.
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Vibration is a priority in the field of construction machinery in the process group dynamic load processing of different materials. Presented here are models with basic mathematical relationships that we utilize to describe phenomena in the task of modeling any process of dynamic loads acting on the treated medium. In the presented material, diagrams are considered necessary when dealing with specific parameters modeling of real processes of rheological effects on the body: elastic-inertial, viscous-inertial and yielding-inertial on, for example, treatments of concrete mixes.
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Shcherban’, E., A. Beskopylny, L. Mailyan, S. Stel’makh, and D. El’shaeva. "Mathematical modeling of mechanical properties of vibro-centrifuged fiber-reinforced concrete of variatropic structure." Journal of Physics: Conference Series 2131, no. 3 (December 1, 2021): 032090. http://dx.doi.org/10.1088/1742-6596/2131/3/032090.
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Abstract Today, one of the most relevant areas in the construction industry, linked to the requirements and provisions of the Strategy of Scientific and Technological Development, and in accordance with the priority areas of science and technology development, is the development and improvement of low-material, low-energy and low - resource-intensive technologies for the manufacture of concrete and reinforced concrete products and structures. In this regard, the technology of vibrocentrifugation, which allows to obtain concrete with an improved variatropic structure, is quite promising. In this work, the influence of the design parameters of the technological equipment and the parameters of the centrifugation modes on the integral strength characteristics of vibrocentrifugated fiber concrete was evaluated. In total, 13 samples of the annular section were manufactured and tested. Calculations of the integral strength characteristics of vibrocentrifugated fiber concrete depending on the height of the technological protrusions of the clamps and the angular rotation speed were performed by the method of orthogonal composite planning of the 2nd order using the MathCAD program. The mathematical method of planning the experiment is aimed at creating mathematical empirical models that determine the influence of the incoming variable factors on the strength characteristics. Thus, according to the results of experimental studies, the optimal height of the technological protrusions and the angular speed of rotation were determined. Thus, further regulation of technological factors in the manufacture of vibrocentrifugated products and structures will allow us to obtain the most effective ring-section structures with enhanced variatropy.
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Sivilevičius, Henrikas. "INFLUENCE OF HOMOGENEITY OF MINERAL MATERIALS' GRADING AND DOSING ERRORS ON THE STABILITY OF ASPHALT CONCRETE MIXTURE COMPOSITION." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 9, no. 1 (March 31, 2003): 25–35. http://dx.doi.org/10.3846/13923730.2003.10531298.
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Errors of optimal composition asphalt concrete mixture designed in the laboratory and their importance for road construction are investigated. After the analysis of asphalt concrete production according to the traditional technology, factors influencing its structure, characteristics and quality are systematised. Mathematical models of dependence of medium quadratic deviations of siftings of finite dosed mineral materials through control sieves on the means of siftings are estimated by a regressive analysis. Variations of grading of hot fractions 0–5 mm and 5–15 mm as well as cold mineral powder sieved through technological sieves of mixing equipment and influence of errors of dosing these mineral materials in the produced mixture on the stability of quantity of containing mineral components (crushed stone, sand and mineral filler) are identified. The main trends of asphalt concrete structure and handling of its equipment methods improvement are presented.
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Semerak, M., N. Ferents, D. Kharyshyn, and S. Vovk. "MATHEMATICAL MODELING OF STRENGTH-DEFORMED CONDITION OF PIPE CONCRETE CONSTRUCTIONS AT SUSTAINABLE TEMPERATURE." Fire Safety 35 (February 26, 2020): 63–68. http://dx.doi.org/10.32447/20786662.35.2019.10.
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The mathematical modeling of the thermo-stressed state of pipe-concrete structures under conditions of stationary thermal conductivity is carried out. During the study, the most common structural type of TBC was selected and mathematical models of the stress-strain state of TBA under heating conditions were taken into account, taking into account their geometric dimensions and thermophysical characteristics of metal and concrete. The main feature of the TBC study is that the heat exchange in the structure, as well as the corresponding force response, are investigated independently of each other, whereas the problem of fire resistance should be posed as a classical problem of elasticity, taking into account the mutual influence of temperature and mechanical stresses.
In two-layer structures (concrete - metal), the largest radial stresses that occur in concrete work in tension. Tensile stresses occur in the thickness of the outer tube. The stresses occurring on the inner surface of the steel sleeve coincide with the stresses in the concrete. When approaching the outer surface, they decrease and on the surface r = R2 equal to zero. In the case where the coefficients of linear extension αt (i = 1, 2) are equal to each other, the maximum tensile stresses are reduced within 0≤r≤R1 .; if νi (i = 1, 2) within 0≤ r≤R2, the stresses will also decrease. Axial stresses work on compression. They reach maximum value in the outer shell. For equal values αt (1) = αt (2), the magnitude of the stresses does not change, and at ν1 = ν2 the stresses in the metal will decrease. Ring stresses in the region 0≤ r≤R1 are tensile stresses and in the region R1≤ r≤R2 are compression stresses, and the compression stresses are greater than the tensile stresses in concrete. For αt (1) = αt (2), the stresses in the concrete decrease and for ν1 = ν2.
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ZHARNITSKIY, V. YA, P. A. KORNIENKO, and A. P. SMIRNOV. "Mathematical modeling of thermal processes in the «Concrete-soil» system." Prirodoobustrojstvo, no. 3 (2022): 71–76. http://dx.doi.org/10.26897/1997-6011-2022-3-71-76.
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The calculation of concrete curing modes and the development of mathematical models are greatly influenced by the temperature field in the concrete of channel linings. The problem is reduced to solving a nonlinear heat equation that takes into account the exothermic heat release of concrete and the phase transformation of moisture, and time-varying boundary conditions that allow taking into account the impact on concrete of the external environment during laying and maintenance. Variable thermophysical coefficients make it possible to take into account the inhomogeneity of the medium (in the case of laying concrete on the ground) and the change in the aggregate state of the substance when the phase transformation temperature is reached. Since it is impossible to obtain an analytical solution in a general form, a numerical solution method is used, based on a combination of a finite-difference solution with a method for calculating heat release and concrete strength from the corresponding fields of isothermal curves obtained experimentally. When constructing a difference scheme, an integro-interpolation method (balance method) is used, based on the law of conservation of heat. For an extended body of sufficiently large dimensions, the process of heat transfer in it is assumed to be linear, and the coordinate system with the center is taken to be on the axis of the body. The presented mathematical model of thermal processes in the “concrete-soil” system makes it possible to predict the modes of holding monolithic concrete to achieve the necessary technological requirements, as well as to apply the most economical modes.
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Zambon, Ivan, Anja Vidović, and Alfred Strauss. "Reliability of Existing Concrete Structures Determined with Physical Models - Carbonation Induced Corrosion." Solid State Phenomena 259 (May 2017): 255–60. http://dx.doi.org/10.4028/www.scientific.net/ssp.259.255.
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The main goal of transportation infrastructure management is to optimize the use of infrastructure in the most beneficiary way while respecting the predefined requirements. One of the crucial parts in management strategy is the prediction of behaviour of vital transportation elements. Used prediction models should accurately describe the process of degradation and allow forecasting of structural condition by considering environment, usage and maintenance actions. Deterioration models can be divided into mathematical (statistical), physical and empirical models. Statistical models are based on data that describe condition of structure, such as for example condition rating. Physical models describe damage-causing processes and empirical models are experience based. The focus of this paper is to present the physical model of carbonation in assessment of performance of existing reinforced concrete structures in transportation networks. Assessment is done through determining the probability of limit state of depassivation. In order to determine the carbonation without testing, a special attention has to be given to environmental and material parameter identification. Herein, the identification takes into account weather specifics and construction practice in Austria. Finally, the reliability of existing reinforced concrete structures for combination of different exposure classes and material characteristics is analysed. Based on the analysis of reliability, the carbonation nomogram for engineering use is presented, showing the reliability indices β for the service life of 50 years.
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Kessal, Oussama, Larbi Belgraa, Noura Djebri, Soumia Salah, and Zineb Allal. "Improvement of the Mechanical Behavior of an Environmental Concrete Based on Demolished Concrete Waste and Silica Fume." Civil Engineering Journal 8, no. 2 (February 1, 2022): 238–50. http://dx.doi.org/10.28991/cej-2022-08-02-04.
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The universal need to conserve resources, protect the environment, and use energy efficiently must necessarily be felt in the field of concrete technology. In Algeria, the rapid growth in the construction sector and the difficulties in setting up new quarries make it necessary to find effective alternatives to use them as building materials. The recycling of construction and demolition waste as a source of aggregates for the production of concrete has attracted growing interest from the construction industry. In this context, this work is a part of the approach to provide answers to concerns about the lack of aggregates for concrete. It also aims to develop the inert fraction of demolition materials, mainly concrete construction demolition waste (C&D), as a source of aggregates for the manufacture of new hydraulic concrete based on recycled aggregates. This experimental study presents the results of physical and mechanical characterizations of natural and recycled aggregates, as well as their influence on the properties of fresh and hardened concrete. The characterization of the materials used has shown that the recycled aggregates have heterogeneity, a high-water absorption capacity, and medium-quality hardness. However, the limits prescribed by the standards in force do not disqualify these materials from use for application as recycled aggregate concrete. The effect of silica fume and superplasticizer percentage on the mechanical and physical properties of concrete with NA and RA was analyzed and optimized using full-factorial design methodology. The results obtained from the present study show acceptable mechanical, compressive, and flexural strengths of concrete based on recycled aggregates by using Superplasticizer and 5% of silica fume, compared to those with natural aggregates. The results of the water absorption as well as the UPV confirm the positive effect of the use of superplasticizer and silica fume on the physical and mechanical behavior of concrete with recycled aggregates. Factorial design analysis shows that the developed mathematical models can be used to predict the physical and mechanical properties of concrete with RAC, superplasticizer, and silica fume. Doi: 10.28991/CEJ-2022-08-02-04 Full Text: PDF
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Gallyamova, Tat’yana R. "Probabilistic Model of the Reflectivity of Construction Materials of the Agroindustrial Complex." Elektrotekhnologii i elektrooborudovanie v APK 3, no. 44 (September 2021): 111–15. http://dx.doi.org/10.22314/2658-4859-2021-68-3-111-115.
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When developing modern lighting technologies for objects of the agro-industrial complex, the problem arises of assessing the contribution of reflected light to the normalized illumination. The reflective properties of the surfaces of materials are characterized by a reflection coefficient ρ, which reaches a value of 0.7. This allows us to consider the reflective surfaces as an additional light source and the possibility of reducing energy consumption costs. (Research purpose) The research purpose is in developing a mathematical model that allows us to estimate the spectral reflection coefficient ρ(λ) of materials of construction technologies of the agro-industrial complex in the ultraviolet and visible spectral regions. (Materials and methods) That the disadvantage of various models is the lack of an analytical method for calculating the reflection coefficient in a wide range of wavelengths. We used a probabilistic method to overcome this disadvantage. (Results and discussion) The developed mathematical model makes it possible to estimate the reflection coefficient of the rough surface of materials in a wide range of the spectrum. For concrete, the area of agreement between theory and experiment is in the wavelength range from 250 to 1000 nm. The saturation mode predicted by the theory (the independence of the reflection coefficient from the wavelength) at a reflection coefficient of 0.4 is consistent with the experimental values in the visible range of the spectrum for construction materials of the agro-industrial complex, in particular, gray textured concrete, gray facade paint, light wood, gray silicate brick, new plaster without whitewash. (Conclusions) In the case of normal light incidence, the developed mathematical model allows us to theoretically estimate the reflection coefficient of the rough surfaces of construction technologies of the agro-industrial complex. The proposed model can be used in the development and design of a system of technological lighting of large-area premises (for example, when keeping birds on the floor), as well as for developing recommendations for reducing the energy consumption of existing lighting systems.
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Aniskin, Nikolai A., and Alexey M. Shaytanov. "A full-scale study on the thermal emissivity of concrete and application of its findings to verify ANSYS software package." Vestnik MGSU, no. 6 (June 2022): 727–37. http://dx.doi.org/10.22227/1997-0935.2022.6.727-737.
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Introduction. One of the most popular and complex areas in the design of massive concrete structures is the analysis of their thermal behaviour and thermal stress state. Hence, we can identify tasks related to the phased construction of massive concrete structures, such as gravity dams, massive foundations, bridge supports, etc. A large number of factors, influencing the thermal process, varying over time and depending, among other things, on temperature, determine the complexity of such tasks. The main factor, determining the thermal behaviour of mass concrete in the process of construction, is the exothermic heating of concrete, depending on the type and amount of cement used, as well as several process specifications. Today, such problems can be best solved using the numerical finite element method, implemented in numerous software products. One of them is ANSYS software package, which is widely used to analyze constructions and structures in respect of a full range of actual loadings and impacts. This paper presents the results of the field studies conducted to obtain the initial parameters and verify the precision of results obtained using mathematical modeling techniques of the ANSYS software package.
Materials and methods. The authors describe a full-scale experiment that entails the concreting of a concrete testing block. During concrete placing and curing, temperature sensors time tested a temperature change inside the block and in the outside air. Also, studies were conducted using the numerical finite element method employed by the ANSYS software package.
Results. The findings of a full-scale experiment were compared with the thermal behaviour analysis made by the ANSYS software package. The comparison has proven highly precise results. The maximum temperature difference at the selected points of the full-scale and numerical models does not exceed 0.6 %.
Conclusions. The ANSYS software package solves complex tasks with high accuracy; it determines the thermal behaviour of massive concrete structures, taking into account the thermal emissivity during cement hydration.
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Gour, Chandra Prakash, Priyanka Dhurvey, and Nagaraju Shaik. "Optimization and Prediction of Concrete with Recycled Coarse Aggregate and Bone China Fine Aggregate Using Response Surface Methodology." Journal of Nanomaterials 2022 (October 7, 2022): 1–11. http://dx.doi.org/10.1155/2022/2264457.
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Construction recycled material is crucial for protecting natural resources and promoting sustainable human development in a rapidly industrializing world. Many administrations worldwide accepted that it is beneficial to use demolition waste in the concrete building industry to reduce manufacturing costs and minimize the use of virgin aggregates. However, control measures should be done as their mechanical properties are poorer than traditional aggregates. To overcome this problem, pozzolanic materials like bone chine can be incorporated, providing extra CSH gel, which improves mechanical strength. Therefore, this research is aimed at producing eco-friendly concrete, which can be used for medium-grade strength, using recycled construction waste (RCA) as coarse and bone china fine aggregate (BCA) as fine aggregate. Workability, density, compressive, split tensile, and flexural strength are used to compare the fresh and hardened properties of the concrete. Experimental and statistical research is employed in the current study to evaluate the impact of RCA and BCA on the performance of concrete. To simulate all measurable responses, including workability, density, compressive, flexural, and split strength, RSM (response surface methodology) was utilized. The CCD (Central Composite Design) approach in RSM was used to create and analyze mixes in an experiment. Based on the experiment’s results, mathematical models were designed and assessed using the analysis of variance test (ANOVA). The analysis of variance results demonstrated the statistical significance of each constructed model. Three-dimensional response surface plots created using established regression models were used to investigate the interaction between the respective variables and to optimize the mixing ratio. The results indicate that the optimum utilization of RCA is up to 40% and BCA up to 60% as coarse and fine aggregate replacement in concrete, respectively, which not only helps to reduce costs but also offers sustainability. Finally, it was concluded that the generated models might be employed by obtaining the maximum tested features of concrete to assure a quick mix design approach. To conduct the microstructure study, thin section techniques were used to observe a strong aggregate-matrix interaction.
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Legatiuk, Dmitrii. "Mathematical Modelling by Help of Category Theory: Models and Relations between Them." Mathematics 9, no. 16 (August 15, 2021): 1946. http://dx.doi.org/10.3390/math9161946.
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The growing complexity of modern practical problems puts high demand on mathematical modelling. Given that various models can be used for modelling one physical phenomenon, the role of model comparison and model choice is becoming particularly important. Methods for model comparison and model choice typically used in practical applications nowadays are computation-based, and thus time consuming and computationally costly. Therefore, it is necessary to develop other approaches to working abstractly, i.e., without computations, with mathematical models. An abstract description of mathematical models can be achieved by the help of abstract mathematics, implying formalisation of models and relations between them. In this paper, a category theory-based approach to mathematical modelling is proposed. In this way, mathematical models are formalised in the language of categories, relations between the models are formally defined and several practically relevant properties are introduced on the level of categories. Finally, an illustrative example is presented, underlying how the category-theory based approach can be used in practice. Further, all constructions presented in this paper are also discussed from a modelling point of view by making explicit the link to concrete modelling scenarios.
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Belostotsky, Alexander M., Pavel A. Akimov, Andrey A. Aul, Dmitry S. Dmitriev, Yulia N. Dyadchenko, Alexander I. Nagibovich, Konstantin I. Ostrovsky, and Andrey S. Pavlov. "Analysis of Mechanical Safety of Stadiums for the World Cup 2018." Scientific journal “ACADEMIA. ARCHITECTURE AND CONSTRUCTION”, no. 3 (September 27, 2018): 118–29. http://dx.doi.org/10.22337/2077-9038-2018-3-118-129.
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It is obvious that contemporary design and construction of unique buildings and structures is unthinkable without mathematical (numerical) and computer modelling and advanced analysis ofload-bearing structures under various kinds ofloads and impacts. One of the most ambitious and important construction projects is the uniquelarge-span structures. These are, in particular, stadiums, sports palaces and water parks, shopping malls, pedestrian, road and railway bridges of various design solutions. The distinctive paper is devoted to theoretical foundations and results of mathematical (numerical) modeling of the state (in terms of the analysis of stress-strain state, strength and stability) of football stadiums built for the 2018 FIFA World Cup in Russia. Finite element method is used for approximation and high-precision numerical solution of corresponding boundary problems of structural mechanics. It is the most universal and powerful numerical method of mechanics. The paper, in particular, describes some features of development of finite element models and the main results of the analysis of the mechanical (structural) safety of three- dimensionallarge-span systems "soil foundation - reinforced concrete structures of foundations and stands - steel structures of the coating and facades" of these football stadiums with the basic and specialload combinations. In addition, the key procedures of scientific support during the corresponding expertise and assessments are outlined. Generally, socially significant and knowledge-intensive problem of providing mechanical (constructive) safety of unique combined objects of construction (three-dimensional systems "foundation - reinforced concrete structures of foundations and stands - steel structures of coating and facades") has been solved at a new level as a result of the performed complex of research works.
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Meruane, Viviana, Sergio J. Yanez, Leonel Quinteros, and Erick I. Saavedra Flores. "Damage Detection in Steel–Concrete Composite Structures by Impact Hammer Modal Testing and Experimental Validation." Sensors 22, no. 10 (May 20, 2022): 3874. http://dx.doi.org/10.3390/s22103874.
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Steel–concrete composite systems are an efficient alternative to mid- and high-rise building structures because of their high strength-to-weight ratio when compared to traditional concrete or steel constructive systems. Nevertheless, composite structural systems are susceptible to damage due to, for example, deficient construction processes, errors in design and detailing, steel corrosion, and the drying shrinkage of concrete. As a consequence, the overall strength of the structure may be significantly decreased. In view of the relevance of this subject, the present paper addresses the damage detection problem in a steel–concrete composite structure with an impact-hammer-based modal testing procedure. The mathematical formulation adopted in this work allows for the identification of regions where stiffness varies with respect to an initial virgin state without the need for theoretical models of the undamaged structure (such as finite element models). Since mode shape curvatures change due to the loss of stiffness at the presence of cracks, a change in curvature was adopted as a criterion to quantify stiffness reduction. A stiffness variability index based on two-dimensional mode shape curvatures is generated for several points on the structure, resulting in a damage distribution pattern. Our numerical predictions were compared with experimentally measured data in a full-scale steel–concrete composite beam subjected to bending and were successfully validated. The present damage detection strategy provides further insight into the failure mechanisms of steel–concrete composite structures, and promotes the future development of safer and more reliable infrastructures.
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Ksaibati, Khaled, Menglan Zeng, Fane R. Sellers, and Charles W. Dolan. "Air Change in Hydraulic Concrete Due to Pumping." Transportation Research Record: Journal of the Transportation Research Board 1834, no. 1 (January 2003): 85–92. http://dx.doi.org/10.3141/1834-11.
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The air content of concrete plays an important role in the durability of concrete. Excess air may reduce the strength of the concrete, while inadequate air will result in premature deterioration of the concrete due to scaling caused by freeze–thaw cycles and deicing chemicals. Pumping of hydraulic concrete has been a common practice for placing concrete. Although the air content before pumping is relatively easy to control, the air change during pumping has not been well understood. The purpose of this study was to investigate the change in air content of hydraulic concrete caused by pumping. Air content and other properties of concrete before and after pumping were measured at 36 construction projects in two phases. Analysis on data from 31 projects in Phase I indicated that most concrete experiences air loss because of pumping. Many factors could be behind this air loss. Analysis on data from five control projects in Phase II indicated that sampling methods had a moderate effect on the air change. Errors in measurement were minimal for certified testers and calibrated pots. The air change of concrete was significantly affected by the configuration of the boom, in addition to the air content before pumping. Attachments to the boom played key roles in reducing the air loss. Two mathematical models were developed for the prediction of air loss.
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Lisienkova, Liubov, Tatiana Shindina, Nina Orlova, and Liudmila Komarova. "Optimization of the Concrete Composition Mix at the Design Stage." Civil Engineering Journal 7, no. 8 (August 1, 2021): 1389–405. http://dx.doi.org/10.28991/cej-2021-03091732.
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The problem of the composition optimization of concrete mixes seems to be quite urgent as errors at the composition design stage can lead to problems of concrete at the stage of exploitation such as delamination, cracking etc. Reasonable selection of concrete mix components guarantees the required strength of concrete and reinforced concrete structures in the future. This paper investigates the influence of the concrete mix composition on the strength of concrete. Firstly, typical risks that can occur on the composition design stage have been identified through the experts' interviews. Secondly, this risks were associated with indicators and characteristics that can be tested experimentally. Running of several mathematical models has allowed to outline concrete mix parameters of highest importance and formulate an empirical equation for the dependence of the strength of the concrete mixture on the values of the coarse aggregate quality factor, the fine aggregate fraction and the consumption of the Portland cement has been proposed. As a result, a methodology for controlling the quality of concrete at the stage of the composition design has been formulated. Doi: 10.28991/cej-2021-03091732 Full Text: PDF
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ZHARNITSKY, V. YA, and P. A. КОRNIENKO. "EXPERIMENTAL RESEARCH OF THE NON-VIBRATING METHOD OF LAYING CONCRETE MIXTURE IN CANAL CLADDING." Prirodoobustrojstvo, no. 3 (2021): 88–94. http://dx.doi.org/10.26897/1997-6011-2021-3-88-94.
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The results of experimental studies are presented which make it possible to correct the technological parameters of laying the concrete mixture in the cladding of newly erected or reconstructed water supply canals. The studies were carried out on an experimental stand simulating the cannel profi le with a variable slope angle from 15° to 90°. The stand slope is covered with a conditional soil model in the form of a rough surface. To determine the relationship between the speed of the vibromold movement, the parameters of the concrete mixture, the profi le of the canal and the parameters of the concrete paver, mathematical models of the technological process have been developed. The analysis of the obtained results shows that accelerating additives signifi cantly reduce the duration of the concrete reaching its critical strength, in other words, it reduces the duration of the curing of the concrete under the formwork. The study of the obtained surface of the cladding on the stand shows that it contains some irregularities due to the absence of a smoothing strip. Therefore, under production conditions, concrete pavers must be equipped with smoothing devices, and the concrete mixture must be placed through a special hopper that regulates the height of the concrete mixture supply. For the construction of concrete linings on mobile concrete mixtures, it is recommended to use accelerating additives or their preliminary heating to a temperature of 50 … 60°C.
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Khed, Veerendrakumar C., Vyshnavi Pesaralanka, Musa Adamu, Yasser E. Ibrahim, Marc Azab, Achyutha Kumar Reddy, Ahmad Hakamy, and Ahmed Farouk Deifalla. "Optimization of Graphene Oxide Incorporated in Fly Ash-Based Self-Compacting Concrete." Buildings 12, no. 11 (November 17, 2022): 2002. http://dx.doi.org/10.3390/buildings12112002.
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Self-compacting concrete (SCC) was developed to overcome the challenges of concrete placement in dense or congested reinforcement structure, where the concrete can flow under its own weight to fill the densely reinforced structure. However, production of SCC mostly involves the use of high cement to achieve the desired strength. Therefore, to reduce the needed amount of cement, pozzolanic materials such as fly ash can be used to partially replace cement. However, fly ash has been reported to decrease the strengths of concrete especially at early ages. In this study, a self-compacting concrete (SCC) was developed with fly ash as a basic replacement material considering the efficiency of fly ash and incorporating graphene oxide (GO) as a cement additive to counteract the negative effect of fly ash. Response surface methodology (RSM) was utilized for designing the experiments, investigating the effects of fly ash and GO on SCC properties, and developing mathematical models for predicting mechanical properties of SCC. The ranges of fly ash and graphene oxide were 16.67 to 35% and zero to 0.05%, respectively. Statistical analysis was performed by using Design Expert software (version 11.0, Stat Ease Inc., Minneapolis, MS, USA). The results showed that fly ash had a positive effect while GO had a negative effect on the workability of SCC. The incorporation of fly ash alone decreased the compressive strength (CS), splitting tensile strength (STS) and flexural strength (FS), and additionally, increased the porosity of SCC. The addition of GO to fly ash-based SCC reduced its porosity and enhanced its mechanical strengths which was more pronounced at early ages. The developed models for predicting the mechanical strengths of fly ash-based SCC containing GO have a very high degree of correlation. Therefore, the models can predicts the strengths of SCC using fly ash and GO as the variables with a high level of accuracy. The findings show that based on the EFNARC guidelines, up to 35% of fly ash can be used to replace cement in SCC to achieve a mix with satisfactory flowability and deformability properties
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Utami, Lintang Fitra, Ikrar Pramudya, and Isnandar Slamet. "Students' Mathematical Communication Skills in Terms of Concrete and Abstract Sequential Thinking Styles." Al-Jabar : Jurnal Pendidikan Matematika 11, no. 2 (December 19, 2020): 371–81. http://dx.doi.org/10.24042/ajpm.v11i2.7486.
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This study aimed to analyze and describe the eleventh-grade senior high school students' mathematical communication skills on linear program material in terms of concrete and abstract sequential thinking styles. This study employed a qualitative descriptive approach with the case study method. The sampling technique used was the purposive sampling technique. The mathematical communication skills test and thinking style questionnaires were employed as the data collecting technique. The analysis revealed that subjects in the AS category could make generalizations based on good reasoning in the written text aspect. On the other hand, subjects in the CS category were having a hard time constructing abstract assumptions. In the drawing aspect, subjects in the AS category showed good theories and concept understanding. In contrast, subjects in the CS category were only able to apply some of the information to draw graphs. In mathematical expressions, subjects in the AS category could process the information implied by the problem to make mathematical models correctly. Meanwhile, subjects in the CS category needed additional information or direction to understand the information to avoid mistakes.
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Mohammed, Ahmed Salih, Wael Emad, Warzer Sarwar Qadir, Rawaz Kurda, Kawan Ghafor, and Raed Kadhim Faris. "Modeling the Impact of Liquid Polymers on Concrete Stability in Terms of a Slump and Compressive Strength." Applied Sciences 13, no. 2 (January 16, 2023): 1208. http://dx.doi.org/10.3390/app13021208.
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It is generally known that the two most crucial elements of concrete that depend on the slump value of the mixture are workability and compressive strength. In addition, slump retention is more delicate than the commonly used slump value since it reflects the concrete mixture’s durability for usage in civil engineering applications. In this study, the effect of three water-reducer additives was tested on concrete’s workability and compressive strength from 1 day to 28 days of curing. The slump of the concrete was measured at the time of adding water to the mix and after 30 min of adding water. This study employed 0–1.5% (%wt) water-reducer additives. The original ratio between water and cement (wc) was 0.65, 0.6, and 0.56 for mixtures incorporating 300, 350, and 400 kg of cement. It was lowered to 0.3 by adding water-reducer additives based on the additives type and cement content. Depending on the kind and amount of water-reducer additives, w/c, gravel content, sand content, crushed content, and curing age, adding water-reducer additives to the concrete increased its compressive strength by 8% to 186%. When polymers were added to the concrete, they formed a fiber net (netting) that reduced the space between the cement particles. As a result, joining the cement particles quickly enhanced the fresh concrete’s viscosity and the hardened concrete’s compressive strength. The study aims to establish mathematical models (nonlinear and M5P models) to predict the concrete compressive strength when containing water-reducer additives for construction projects without theoretical restrictions and investigate the impact of mix proportion on concrete compressive strength. A total of 483 concrete samples modified with 3 water-reducer additives were examined, evaluated, and modeled for this study.
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Kuznetsov, A. A., A. S. Bryukhova, and N. V. Volkova. "Application of Experiment Planning Methods in Researching of Reinforced Concrete Constructions Corrosion Process." Materials Science Forum 992 (May 2020): 857–62. http://dx.doi.org/10.4028/www.scientific.net/msf.992.857.
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The article discusses statistical methods of experiment planning for determining the significance of influencing factors on the course of the corrosion process. The application of the proposed method in conjunction with spectral monitoring methods is shown. Mathematical models are presented that allow to investigate the corrosion process with various combinations of influencing factors. The response surface of the dependent variable on the most significant factors is constructed. The conclusion is made that spectral methods can be used to determine the corrosion state of reinforced concrete structures.
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ZHARNITSKIY, V. YA, and A. P. SMIRNOV. "MATHEMATICAL MODEL OF MATERIALS OF STRUCTURES AND ELEMENTS OF RESTORED SOIL DAMS FOR NUMERICAL CALCULATIONS." Prirodoobustrojstvo, no. 4 (2021): 46–51. http://dx.doi.org/10.26897/1997-6011-2021-4-46-51.
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Identified in the process of analyzing the operation of the structure, in the conditions of its operation, allow to assess the actual reserves of the bearing capacity of the structure and take effective measures to restore the operational parameters. The main criteria influencing the choice of mathematical models of materials for structures and elements of soil dams are more consistent with the model of the equation of state connecting the components of stress and strain tensors, as well as the rate of their change, which are obtained and tested for numerical calculations and have a full set of constants for materials used in the calculations of earth dams, the choice of their structures (concrete,reinforced concrete, soils, etc.). Reliable operation of soil dams is possible only if all proper conditions are met. The causes of dam accidents and their damage must be known not only to eliminate errors at the design and construction stages, but also during their operation. In order to exclude the negative impact of operational factors on the safety of soil HTS, it is necessary not only to strictly observe the rules of technical operation and take measures to exclude the possibility of an emergency situation during technological operations at facilities, but also to have methods for predictive justification of the restoration of strength and operational indicators of structures and elements of soil dams.
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Xing, Feng, Xiang Yong Guo, Fa Guang Leng, Kun He Fang, and Ren Yu Zhang. "Study on Distribution Feature of Fracture Toughness of Interface between Coarse Aggregate and Hardened Cement Mortar in Concrete." Key Engineering Materials 302-303 (January 2006): 514–20. http://dx.doi.org/10.4028/www.scientific.net/kem.302-303.514.
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Based on available test data and fracture criterion, by using probability fracture mechanics and mathematical statistical method, the distribution feature of fracture toughness, IC K , of interface between coarse aggregate and hardened cement mortar is analyzed, and a method of defining the least number of specimens for testing fracture toughness is provided. Weibull distribution or lognormal distribution is often used to analyze lifetime problem, so the two models are preferentially considered. The analysis shows that the fracture toughness conforms to lognormal distribution with degree of confidence g =0.9, relative deviation d =0.05 and the least number of specimens of 13. The study results can be used in the probability fracture analysis and construction quality control of interface between coarse aggregate and hardened cement mortar.
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Krus, Yurii. "CONNECTION BETWEEN STRESSES AND STRAINS OF CONCRETE UNDER DIFFERENT FORCE MODES OF SHORT-TERM AXIAL COMPRESSION." Technical Sciences and Technologies, no. 1(27) (2022): 184–98. http://dx.doi.org/10.25140/2411-5363-2022-1(27)-184-198.
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Modern design of bended reinforced concrete constructions uses analytical methods of calculation involving deformative models, the main tool of which is the actual diagram of concrete state, which establishes the connection between its stressesband relative strains bin compressed and tensile zones of the cross-section. Currently, there is no a unified methodics of establishing such a diagram, and researchers obtain it by indirect methods that differ from each other. That is why the graph-analytical building and mathematical description of the functional dependence of the diagram of concrete state based on clearand accurate physical representations we consider as an important and urgent problem.The lackof a unifiedmethodics for obtaining a diagram of concrete state cast doubt the reliability of the results of the calculations carried out, does not allow to compare, explain and link into a unifiedwhole the many experimental and theoret-ical data accumulated by generations of researchers.In a number of scientific publications, an opinion is expressed that a diagram of concrete state can be obtained by simultaneous using of diagrams of concrete deforming under different force modes of short-term axial compression –«soft» and «rigid», testing standard concrete specimens to failure at a constant rate of stress and strains growth respectively. If the «soft» force mode without unnecessary difficulties can be realized on traditional hydraulic presses, the creation of «rigid» mode requires the manufacture of different from standard special presses or auxiliary devices, capable of taking efforts and unloading concrete after reaching the maximum of compressive stresses. The lack of a unified approach to obtaining diagrams of deforming under rigid-mode loadings leads to contradictory results.Insufficiently investigated in the general problem are the issues of theoretical justification, development and approbation of diagram of concrete rigid-mode deforming bb~, complex application of which simultaneously with the diagram of de-forming bb~in conditions of «soft»force mode will allow to obtain a reliable and convincing diagram of concrete state.The main purpose of the research is a graph-analytical building and mathematical description of the dependence bb~, based on clear and accurate physical representations, which experimental obtaining causes serious technical difficulties and eco-nomic costs, and the accuracy of measurements made and the reliability of the results obtained causes big doubts.The article develops the criteria to which the dependence bb~should correspond, based on modern ideas about the nature of strength and deforming and following from the essence of physical and mechanical processes in concrete; the ade-quate structure of the functional connection has been established; the boundary conditions have been drawn up and constant coefficients have been determined; a comparative analysis of the calculation results using the proposed dependence with the corresponding experimental data was performed.As a result, an easy-to-use and mathematical processing of an approximate function of the diagram of deforming is proposed, which reflects the dependence between stresses and strains of concrete under the «rigid» mode of homogeneous compression. Its simultaneous use with the previously obtained diagram for soft-mode loading makes it possible to graphically build and mathematically describe a stable and free from excessive influencing factors the diagram of concrete state, suitable for based on the deformative model of cross-sections of modern calculations of bended reinforced concrete constructions for all groups of limiting states and assessment of the heterogeneous stress-strain state of constructional cross-sections at any stage of loading up to fracture.
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Ponce-Farfán, Cristian, David Santillán, and Miguel Á. Toledo. "Thermal Simulation of Rolled Concrete Dams: Influence of the Hydration Model and the Environmental Actions on the Thermal Field." Water 12, no. 3 (March 19, 2020): 858. http://dx.doi.org/10.3390/w12030858.
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Mathematical models for the simulation of the thermal evolution of roller-compacted concrete (RCC) dams during construction constitute an important tool for preventing excessive temperature rise, which may lead to cracking and losses of functionality. Here, we present a framework for the simulation of the thermal process. We define the boundary conditions of the problem using a careful description that incorporates the main heat exchange mechanisms. We adopt both a non-adiabatic and an adiabatic heat generation model for the simulation of the cement hydration. Our numerical framework lets us study the effect of the adopted heat generation model on the thermal field. Moreover, we study the influence of the weather conditions on the evolution of the hydration, and on the starting date of construction. Our simulations have shown that the hydration model has an important influence over the temperature field during the construction and the heat generation rate. Moreover, the hydration process and the temperature evolution are driven by the weather conditions. Once the next lift is cast, its thermal insulation effect makes the hydration take place under quasi-adiabatic conditions. As expected, dams built in cold months are prone to dissipate more heat than those built in warm seasons.
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Semina, Yuliya Anatol'evna. "THE STRENGTH OF REINFORCED CONCRETE BEAM ELEMENTS UNDER CYCLIC ALTERNATING LOADING AND LOW CYCLE LOAD OF CONSTANT SIGN." Vestnik MGSU, no. 9 (September 2015): 36–50. http://dx.doi.org/10.22227/1997-0935.2015.9.36-50.
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The behavior of reinforced concrete elements under some types of cyclic loads is described in the paper. The main aim of the investigations is research of the stress-strain state and strength of the inclined sections of reinforced concrete beam elements in conditions of systemic impact of constructive factors and the factor of external influence. To spotlight the problem of cyclic loadings three series of tests were conducted by the author. Firstly, the analysis of the tests showed that especially cyclic alternating loading reduces the bearing capacity of reinforced concrete beams and their crack resistance by 20 % due to the fatigue of concrete and reinforcement. Thus the change of load sign creates serious changes of stress-strain state of reinforced concrete beam elements. Low cycle loads of constant sign effect the behavior of the constructions not so adversely. Secondly, based on the experimental data mathematical models of elements’ strength were obtained. These models allow evaluating the impact of each factor on the output parameter not only separately, but also in interaction with each other. Furthermore, the material spotlighted by the author describes stress-strain state of the investigated elements, cracking mechanism, changes of deflection values, the influence of mode cyclic loading during the tests. Since the data on the subject are useful and important to building practice, the ultimate aim of the tests will be working out for improvement of nonlinear calculation models of span reinforced concrete constructions taking into account the impact of these loads, and also there will be the development of engineering calculation techniques of their strength, crack resistance and deformability.
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Yankelevsky, DZ, VR Feldgun, and YS Karinski. "Rigid projectile penetration into a concrete medium: A new model." International Journal of Protective Structures 8, no. 3 (August 4, 2017): 473–99. http://dx.doi.org/10.1177/2041419617721542.
Full textAbstract:
A new simplified model to analyze the penetration of a rigid projectile into a concrete thick medium is presented. The concrete medium is modeled by a set of discs, responding in the radial direction under plain strain conditions. A convenient mathematical formulation is derived based on some simplifying assumptions. A major new feature of the present model is that it hybridizes two different analytical and numerical approaches that have been developed by the authors. In the present model, the Riemann problem exact solution is applied to the interaction of the projectile nose tip with the target. It is assumed that when the nose tip meets a new undisturbed disc, loading occurs during its interaction with the concrete, and therefore the unloading branch of the equation of state is not required in the Riemann problem. The other discs that maintain contact with the projectile nose and had been loaded in earlier time steps undergo unloading, and a special approach has been developed to compute their contact stresses. This entirely new formulation has not been proposed earlier. The present model enables calculations of the projectile motion time history (i.e. deceleration, velocity, and depth). Comparison of the present model results with experimental data shows very good agreement. Contrary to many other simplified models, the present approach does not require any empirical constants or any preliminary assumptions concerning the contact pressures acting on the penetrating projectile nose, as other models do. Computer time of less than 1 min is needed for a complete analysis.
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Fan, Ching-Lung, and Yu-Jen Chung. "Supervised Machine Learning–Based Detection of Concrete Efflorescence." Symmetry 14, no. 11 (November 11, 2022): 2384. http://dx.doi.org/10.3390/sym14112384.
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The development of automated systems for detecting defects in and damage to buildings is ongoing in the construction industry. Remaining aware of the surface conditions of buildings and making timely decisions regarding maintenance are crucial. In recent years, machine learning has emerged as a key technique in image classification methods. It can quickly handle large amounts of symmetry and asymmetry in images. In this study, three supervised machine learning models were trained and tested on images of efflorescence, and the performance of the models was compared. The results indicated that the support vector machine (SVM) model achieved the highest accuracy in classifying efflorescence (90.2%). The accuracy rates of the maximum likelihood (ML) and random forest (RF) models were 89.8% and 87.0%, respectively. This study examined the influence of different light sources and illumination intensity on classification models. The results indicated that light source conditions cause errors in image detection, and the machine learning field must prioritize resolving this problem.
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Петренко, Александр, Aleksandr Petrenko, Александр Суворов, Aleksandr Suvorov, Евгения Плотникова, and Evgeniya Plotnikova. "The Influence of False Alarms of Threats Technical Detection Means on the Security System Construction." Safety in Technosphere 7, no. 2 (January 23, 2019): 22–28. http://dx.doi.org/10.12737/article_5c35dbd0a862c5.88839524.
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Some theoretical aspects for determining the required number of mobile groups involved in objects security assurance from the impact of various negative factors have been considered. A mathematical model, that allow substantiate the required number of groups for timely response to negative factors has been developed. The total number of response teams has been determined and corrected with account for probability of false alarm related to several technical detection means. The influence of placement for technical detection means, and response teams, as well as of negative factors’ characteristics on the catch line tailoring has been shown. The negative factor’s catch line sizes in dependence to the detection means’ concrete location have been calculated. A certainty increase for operation of technical detection means is carried out by determining the regularity of triggering moments, taking into account the appearance of false alarms. An inspection for received signals’ certainty is carried out by guard personnel from response teams. The developed model will allow increase the security system’s response time to the negative factor. The specified models will allow develop the software for modeling of real situations.
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Serbenyuk, Symon. "On Some Aspects of the Examination in Econometrics." Journal of Vasyl Stefanyk Precarpathian National University 8, no. 3 (November 3, 2021): 7–16. http://dx.doi.org/10.15330/jpnu.8.3.7-16.
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Teaching econometrics has been studied by a number of researchers, however, there is little information available on the quality of examination and on simplification of tests for demonstration the high-quality knowledge by students in concrete topics of econometrics or mathematical economics.One can note the following main goals of studying the basics of mathematical economics or econometrics by students: forming the notions of mathematical model and of modeling economic processes and phenomena; understanding a role of using mathematical models for economics research and obtaining scientific results; formatting skills for constructing mathematical models in economics, for solving economics problems by mathematical modeling.The main goal of this paper is to simplify test tasks, is to help to students to demonstrate the high-quality knowledge in certain areas of mathematical economics, and also is to construct a system of testing tasks, in which the emphasis was placed on the knowledge and understanding of an algorithm of solving the problem.In the present paper, to quality examine the student knowledge in the basics of mathematical economics, a certain system of tests was constructed and is considered. The main attention is also given to algorithms and techniques of solving some tasks (problems) of mathematical economics. The following topics of mathematical economics are viewed: constructing mathematical models of linear programming, the input-output model, the Monge-Kantorovich transportation problem, the simplex method of linear programming, the graphic method of linear and nonlinear programming, the method of Lagrange multipliers in mathematical optimization. Some primary basic results of studying linear programming, nonlinear programming, and the input-output model are noted.A new system of tests that satisfies the aim of this paper is modeled. The described tests require less time for solving than usual tasks. Here we do not focus on the repetition of auxiliary mathematical knowledge and arithmetic skills. These tests are simplified versions of standard tasks and help students to demonstrate knowledge in the mentioned topics of mathematical economics. The tasks are focused only on the knowledge of basic formulas, techniques, and connections between mathematical objects, economic systems, and their elements.
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Kabanov, Vadim. "Information model for choosing a design solution for providing construction with mortar." E3S Web of Conferences 281 (2021): 04001. http://dx.doi.org/10.1051/e3sconf/202128104001.
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Building materials are usually classified according to the criterion of the possibility of creating a stock at the construction site. Mortars and concrete mixtures have a limited time during which they must be used in the construction of building structures. There are technologies for the use of dry components of mortars from which the mixture is prepared at the construction site. However, the technology of manufacturing mortars at specialized plants is widely used, followed by transportation of the finished cement-sand mixture to the construction site. The problem under consideration raises issues related to the volume of supply of mortars and the intensity of this building material consumption. Within the framework of the research, the tasks of analytical description of the construction and installation work intensity influence on the technological processes of cement-sand mortars delivery to the construction site have been solved, a block diagram of the selection of an economically feasible design solution for providing the production process with a building mixture has been developed. On the basis of the presented results in the form of mathematical dependencies and a block diagram, the conclusions about the influence of a design solution for providing construction with a cement-sand mixture on the duration and construction and installation work cost have been formulated. A graphic representation of the procedure for making a decision on the supply of a construction with a cement-sand mixture is supposed to be used for the development of software that provides a description of the construction processes functioning in space and time, including for 3D models.
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Mailyan, Levon R., Alexey N. Beskopylny, Besarion Meskhi, Sergey A. Stel’makh, Evgenii M. Shcherban, and Oxana Ananova. "Optimization of Composition and Technological Factors for the Lightweight Fiber-Reinforced Concrete Production on a Combined Aggregate with an Increased Coefficient of Structural Quality." Applied Sciences 11, no. 16 (August 8, 2021): 7284. http://dx.doi.org/10.3390/app11167284.
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In recent years, developing lightweight concrete with both the necessary and sufficient strength characteristics is essential in the construction industry. This article studies the influence of the volumetric composition of lightweight fiber-reinforced concrete (LFRC) and the method of its distribution during the preparation of the fiber–concrete mixture on the strength and deformation characteristics of LFRC on a combined aggregate. The optimal grain size of the porous filler was calculated by the mathematical planning method of the experiment. Regression models of the strength and deformation characteristics on the volumetric content of fiber and its distribution method were obtained. The most effective combination of these factors has been determined. The model shows that the increase in compressive strength was 12%, the value of the prismatic strength increased by 25%, the bending tensile strength increased by 34%, and the axial tensile strength increased by 11%. The ultimate strains during axial compression decreased by 10%, axial tension decreased by 12%, and the elasticity modulus increased by 11% compared to the test results of the control composition samples without fiber and pumice. The coefficient of constructive quality (CCQ) of the LFRC on a combined aggregate compared to concrete with the control composition without fiber and pumice showed an increase of more than 32%. It was also found that fiber reinforcement with basalt fibers with a combination of heavy and porous aggregates achieves a synergistic effect together.
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Abdulameer, Abdulameer Layth Saeed, and Nazira T. Dzhumagulova. "Feasibility study of the cost of transporting wastewater for irrigation purposes in the administrative district of Karbala, Iraq." Stroitel'stvo: nauka i obrazovanie [Construction: Science and Education] 11, no. 3 (September 30, 2021): 151–65. http://dx.doi.org/10.22227/2305-5502.2021.3.9.
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Introduction. The study presents an assessment of the economic feasibility of different pipe materials used to transport treated wastewater. The choice was made between pipes made of ductile iron, glass-fiber reinforced polyester (GRP), concrete, and plastic. Hydraulic calculations of operation of an irrigation water supply and distribution system were made using WaterCAD V8i software. Two options of the system operation, that entail different flow rates and diameters, are considered: if the flow rate is equal to 1.16 m3/s and pipe diameters vary from 800 mm to 1,200 mm, and if the flow rate is equal to 4.63 m3/s, and pipe diameters vary from 1,600 to 2,000 mm. Materials and methods. The article analyzes the legal and regulatory documentation on design and construction, urban planning solutions for residential areas, architectural and structural solutions for apartment buildings, statistical and analytical reports on housing construction in Russia, presented on the Internet. Results. Irrigation water represents treated wastewater fed by the wastewater treatment facilities in the city of Karbala, Iraq. Two hydraulic models were designed with account for the above-mentioned costs. Head losses were estimated for each model with regard for all studied materials and pipe diameters using the WaterCAD V8i software and a mathematical model for the purpose of selecting the optimal pipe diameter. Conclusions. A mathematical model was developed to calculate the cost of transporting wastewater in pipes having different diameters and made of four different materials. The ratio of costs to the diameter of pipes, made of four different materials, was identified by developing an empirical equation. The co-authors used the Darcy – Weisbach technique and the Hazen – Williams method to calculate the operating costs with regard for variable diameters, flow rates for the two models, head losses due to friction, annual operation time, annual cost of electric energy, and the energy efficiency of the unit. Thus, a mathematical model was obtained, that can be applied to select the most optimal pipe diameter.