Pub Date : 2019-03-31DOI: 10.22227/2305-5502.2019.1.4
O. Rubin, A. Antonov, S. Lisichkin, I. Baklykov, Nikolay V. Bekin, K. E. Frolov
Introduction. In connection with the long-term operation of hydraulic structures (HPP), the installation of significant temporary loads, the presence of alternating effects on individual structural elements, it is possible to reduce the carrying capacity and strength of reinforced concrete structures. One of the most crucial elements is the reinforced concrete overlap of the machine hall, the work presents field and design studies, a proposal to strengthen the structures with external reinforcement. Materials and methods. The scientific and technical documentation was analyzed, instrumental studies and visual inspections of the state of the structures were carried out, and a 3D mathematical model was developed based on the finite element method. Multivariate non-linear computational studies of the actual stress-strain state of structures have been carried out. Results. Conducted visual and instrumental examination showed the presence of cracking on the lower edge of the reinforced concrete floor of the machine room. The simulation of the actual state of the structures has been carried out; according to the results of calculations, a schematic diagram of the gain of structures has been proposed. Conclusions. As a result of computational studies of stress-strain state, the occurrence of cracks on the lower edge of reinforced concrete floor of the machine hall was confirmed. When applying temporary technological loads to overlap, it is possible to achieve the yield strength of the reinforcement in certain zones. In order to ensure further safe operation of the structures, a conceptual amplification scheme based on the results of stress-strain state calculations has been proposed.
{"title":"ESTIMATED JUSTIFICATION OF TECHNICAL DECISION ON STRENGTHENING REINFORCED CONCRETE MACHINE HALL FLOOR","authors":"O. Rubin, A. Antonov, S. Lisichkin, I. Baklykov, Nikolay V. Bekin, K. E. Frolov","doi":"10.22227/2305-5502.2019.1.4","DOIUrl":"https://doi.org/10.22227/2305-5502.2019.1.4","url":null,"abstract":"Introduction. In connection with the long-term operation of hydraulic structures (HPP), the installation of significant temporary loads, the presence of alternating effects on individual structural elements, it is possible to reduce the carrying capacity and strength of reinforced concrete structures. One of the most crucial elements is the reinforced concrete overlap of the machine hall, the work presents field and design studies, a proposal to strengthen the structures with external reinforcement. Materials and methods. The scientific and technical documentation was analyzed, instrumental studies and visual inspections of the state of the structures were carried out, and a 3D mathematical model was developed based on the finite element method. Multivariate non-linear computational studies of the actual stress-strain state of structures have been carried out. Results. Conducted visual and instrumental examination showed the presence of cracking on the lower edge of the reinforced concrete floor of the machine room. The simulation of the actual state of the structures has been carried out; according to the results of calculations, a schematic diagram of the gain of structures has been proposed. Conclusions. As a result of computational studies of stress-strain state, the occurrence of cracks on the lower edge of reinforced concrete floor of the machine hall was confirmed. When applying temporary technological loads to overlap, it is possible to achieve the yield strength of the reinforcement in certain zones. In order to ensure further safe operation of the structures, a conceptual amplification scheme based on the results of stress-strain state calculations has been proposed.","PeriodicalId":22024,"journal":{"name":"Stroitel stvo nauka i obrazovanie [Construction Science and Education]","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73631988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-03-31DOI: 10.22227/2305-5502.2019.1.1
M. Kirsanov
Introduction. A scheme is proposed for a planar symmetric statically determinate beam truss with a rectilinear lower belt, struts, multidirectional braces and a polygonal outline of the upper belt. The belts of the truss are rectilinear, the hinges are ideal. The truss belongs to the class of regular trusses having periodic cells. The supporting rods are not deformable. The truss is evenly loaded around the nodes of the lower belt. Materials and methods. The task is to deduce the dependence of the deflection of the truss on the number of panels in the span. The deflection is obtained from the Maxwell-Mora formula under the assumption that all the rods have the same rigidity. Forces in the structural rods from the effective uniform load and from the unit vertical in the middle of the span are determined by the method of cutting the nodes. The matrix of the system of linear equations of node equilibrium is made up of the cosines of the forces with the coordinate axes. To compile a system of equations and solve it, the program of symbolic mathematics Maple is used. To obtain the general formula, a number of problems of trusses with a number of panels from 2 to 29 are solved. Sequences of the coefficients of the deflection formula have common terms for which homogeneous recurrence equations are also compiled using the methods of the Maple system using specialized operators. Results. The solutions of recurrence equations have the form of polynomials with coefficients that depend on the parity of the number of panels and contain trigonometric functions. The graphs of the solutions obtained are constructed and analysed. Sharp changes of deflection characteristic for such truss and their non-monotonic character are noted. It is shown that for a fixed, independent on the number of panels, length of the span and the total load, the relative deflection with increasing number of panels first decreases, then varies little. Conclusions. The asymptotic property of the solution is obtained by the methods of the Maple system: an inclined asymptote is found. The slope is calculated using the analytical capabilities of Maple. A simple formula is derived for the horizontal displacement of the mobile support from the action of the load. The dependence is monotonic. The height of the truss is included in the denominator of the formula.
{"title":"ANALYSIS OF THE DEFLECTION OF A TRUSS WITH A DECORATIVE LATTICE","authors":"M. Kirsanov","doi":"10.22227/2305-5502.2019.1.1","DOIUrl":"https://doi.org/10.22227/2305-5502.2019.1.1","url":null,"abstract":"Introduction. A scheme is proposed for a planar symmetric statically determinate beam truss with a rectilinear lower belt, struts, multidirectional braces and a polygonal outline of the upper belt. The belts of the truss are rectilinear, the hinges are ideal. The truss belongs to the class of regular trusses having periodic cells. The supporting rods are not deformable. The truss is evenly loaded around the nodes of the lower belt.\u0000\u0000Materials and methods. The task is to deduce the dependence of the deflection of the truss on the number of panels in the span. The deflection is obtained from the Maxwell-Mora formula under the assumption that all the rods have the same rigidity. Forces in the structural rods from the effective uniform load and from the unit vertical in the middle of the span are determined by the method of cutting the nodes. The matrix of the system of linear equations of node equilibrium is made up of the cosines of the forces with the coordinate axes. To compile a system of equations and solve it, the program of symbolic mathematics Maple is used. To obtain the general formula, a number of problems of trusses with a number of panels from 2 to 29 are solved. Sequences of the coefficients of the deflection formula have common terms for which homogeneous recurrence equations are also compiled using the methods of the Maple system using specialized operators.\u0000\u0000Results. The solutions of recurrence equations have the form of polynomials with coefficients that depend on the parity of the number of panels and contain trigonometric functions. The graphs of the solutions obtained are constructed and analysed. Sharp changes of deflection characteristic for such truss and their non-monotonic character are noted. It is shown that for a fixed, independent on the number of panels, length of the span and the total load, the relative deflection with increasing number of panels first decreases, then varies little.\u0000\u0000Conclusions. The asymptotic property of the solution is obtained by the methods of the Maple system: an inclined asymptote is found. The slope is calculated using the analytical capabilities of Maple. A simple formula is derived for the horizontal displacement of the mobile support from the action of the load. The dependence is monotonic. The height of the truss is included in the denominator of the formula.","PeriodicalId":22024,"journal":{"name":"Stroitel stvo nauka i obrazovanie [Construction Science and Education]","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76039462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.22227/10.22227/2305-5502.2018.4.5
V. Shevyakov
Introduction. The study presents an approach to the correct selection of the gas flow system in the furnace, the dosed air supply to the furnace, the choice of the sizes of the furnace flues, the length of their channels and their number. Coordination of the furnace with the chimney provides the most efficient design of the furnace. The phenomenon that occurs in any heated vertical channel with respect to the ambient air temperature is called “draft” for the chimney and “flue effect” for the sections of the furnace. The draft or flue effect (vacuum or pressure) is expressed in units of pressure (Pa). This channel can create either a vacuum or a head depending on which end of the channel is connected to the atmosphere. Summarizing the values of flue effect on all areas of the furnace, the total value of flue effect for the entire furnace can be obtained. All channel furnaces according to the hot gas flow scheme are divided into two characteristic groups: direct flows and counter flows. Such a difference in the flow of hot gases has a great influence on the total value of the flue effect of the furnace. Since the total draft of the furnace system affects the process of wood combustion, i.e. the chimney draft and the flue effect of the furnace itself, the study of various schemes of the flow of gases in the furnace, has provided the most rational scheme of the flow of gases in the furnace, which got a patent on a utility model, which provides a more uniform process of wood combustion in the residential furnace and thus increases furnace efficiency. The study is aimed to analyze the various schemes of the flow of hot gases in the furnace and the choice of the most rational scheme. Materials and methods. A detailed examination and study of the effect of various gas flow schemes in a residential furnace on the characteristics of the furnace has been carried out. Results. The results of the study and examination have been used to develop recommendations on the choice of the most rational scheme of gas flow in the furnace and the choice of its design values. Conclusions. The results of the work can be recommended in the development of residential furnaces.
{"title":"THE CHOICE OF THE RATIONAL SCHEME OF GAS FLOW IN RESIDENTIAL FURNACE","authors":"V. Shevyakov","doi":"10.22227/10.22227/2305-5502.2018.4.5","DOIUrl":"https://doi.org/10.22227/10.22227/2305-5502.2018.4.5","url":null,"abstract":"Introduction. The study presents an approach to the correct selection of the gas flow system in the furnace, the dosed air supply to the furnace, the choice of the sizes of the furnace flues, the length of their channels and their number. Coordination of the furnace with the chimney provides the most efficient design of the furnace. The phenomenon that occurs in any heated vertical channel with respect to the ambient air temperature is called “draft” for the chimney and “flue effect” for the sections of the furnace. The draft or flue effect (vacuum or pressure) is expressed in units of pressure (Pa). This channel can create either a vacuum or a head depending on which end of the channel is connected to the atmosphere. Summarizing the values of flue effect on all areas of the furnace, the total value of flue effect for the entire furnace can be obtained. All channel furnaces according to the hot gas flow scheme are divided into two characteristic groups: direct flows and counter flows. Such a difference in the flow of hot gases has a great influence on the total value of the flue effect of the furnace. Since the total draft of the furnace system affects the process of wood combustion, i.e. the chimney draft and the flue effect of the furnace itself, the study of various schemes of the flow of gases in the furnace, has provided the most rational scheme of the flow of gases in the furnace, which got a patent on a utility model, which provides a more uniform process of wood combustion in the residential furnace and thus increases furnace efficiency. The study is aimed to analyze the various schemes of the flow of hot gases in the furnace and the choice of the most rational scheme. Materials and methods. A detailed examination and study of the effect of various gas flow schemes in a residential furnace on the characteristics of the furnace has been carried out. Results. The results of the study and examination have been used to develop recommendations on the choice of the most rational scheme of gas flow in the furnace and the choice of its design values. Conclusions. The results of the work can be recommended in the development of residential furnaces.","PeriodicalId":22024,"journal":{"name":"Stroitel stvo nauka i obrazovanie [Construction Science and Education]","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84003040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.22227/10.22227/2305-5502.2018.4.4
O. Mkrtychev, A. Bunov
Introduction. While designing buildings and constructions with an elastomeric bearing with a lead core as a seismic isolation system, it is necessary to make calculations concerning effectiveness and reasonability of its usage. These demands lead to necessity to construct bearings in a common finite-element model, in order to consider how a bearing and a construction work together. Though a calculator has a lot of different variants of elastomeric bearing’s construction, which are connected to their implemented work model. To prove that obtained calculation results are sufficient and accurate, selection criteria of elastomeric bearings implemented work models are necessary. Materials and methods. To get accurate results we will compare elastomeric bearing’s work diagrams and free periods of motion when there are different variants of their numerical modelling with the help of software packages with factory tests results. Results. The researches have shown that lateral force’s and shear’s limit values are the same for all of the observed cases, although free periods of motion and work diagrams differ. Usage of more accurate bearing work model in software package Ansys/LS-Dyna can explain these differences, it can be seen if compare their work’s diagrams. Conclusions. Analysis of constructions with elastomeric bearings’ work, which function according to the idealized linear model, can be possible only for II level constructions. Idealized nonlinear models should be used for I level constructions.
{"title":"VERIFICATION OF ELASTOMERIC BEARINGS FINITE-ELEMENT MODELS IN CALCULATING SOFTWARE PACKAGES","authors":"O. Mkrtychev, A. Bunov","doi":"10.22227/10.22227/2305-5502.2018.4.4","DOIUrl":"https://doi.org/10.22227/10.22227/2305-5502.2018.4.4","url":null,"abstract":"Introduction. While designing buildings and constructions with an elastomeric bearing with a lead core as a seismic isolation system, it is necessary to make calculations concerning effectiveness and reasonability of its usage. These demands lead to necessity to construct bearings in a common finite-element model, in order to consider how a bearing and a construction work together. Though a calculator has a lot of different variants of elastomeric bearing’s construction, which are connected to their implemented work model. To prove that obtained calculation results are sufficient and accurate, selection criteria of elastomeric bearings implemented work models are necessary. Materials and methods. To get accurate results we will compare elastomeric bearing’s work diagrams and free periods of motion when there are different variants of their numerical modelling with the help of software packages with factory tests results. Results. The researches have shown that lateral force’s and shear’s limit values are the same for all of the observed cases, although free periods of motion and work diagrams differ. Usage of more accurate bearing work model in software package Ansys/LS-Dyna can explain these differences, it can be seen if compare their work’s diagrams. Conclusions. Analysis of constructions with elastomeric bearings’ work, which function according to the idealized linear model, can be possible only for II level constructions. Idealized nonlinear models should be used for I level constructions.","PeriodicalId":22024,"journal":{"name":"Stroitel stvo nauka i obrazovanie [Construction Science and Education]","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73239200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.22227/2305-5502.2018.4.3
M. Kirsanov, D. Tinkov
Introduction. We study the oscillations of a massive load on a planar statically definable symmetric truss of a regular type with parallel belts. Truss weight is not included. Free vertical oscillations are considered. The stiffness of the truss rods is assumed to be the same, the deformations are elastic. Lattice of the truss is double with descending braces and racks. New in the formulation and solution of the problem is the analytical form of the solution, which makes it possible in practice to easily evaluate the frequency characteristics of the structure depending on an arbitrary number of truss panels and the location of the load. Materials and methods. The operators and methods of the system of computer mathematics Maple are used. To determine the forces in the rods, the knotting method is used. The common terms of the sequence of coefficients of solutions for different numbers of panels are obtained from solving linear homogeneous recurrent equations of various order, obtained by special operators of the Maple system. Dependence on two arbitrary natural parameters is revealed in two stages. First, solutions for fixed load positions are found, then these solutions are summarized into one final formula for frequency. Results. By a series of individual solutions to the problem of load oscillation using the double induction method, it was possible to find common members of all sequences. The solution is polynomial in both natural parameters. Graphs constructed for particular cases, showed the adequacy of the approach. The discontinuous non-monotonic nature of the intermittent change depending on the number of truss panels and some other features of the solution are noted. Conclusions. It is shown that the induction method, previously applicable mainly to statics problems with one parameter (number of truss panels), is fully operational to the problems of the oscillations of system with two natural parameters. It should be noted that significant labor costs and a significant increase in the time symbolic transformations in such tasks
{"title":"ANALYTICAL SOLUTION OF THE FREQUENCY OF THE LOAD OSCILLATION AT AN ARBITRARY GIRDER NODE IN THE SYSTEM MAPLE","authors":"M. Kirsanov, D. Tinkov","doi":"10.22227/2305-5502.2018.4.3","DOIUrl":"https://doi.org/10.22227/2305-5502.2018.4.3","url":null,"abstract":"Introduction. We study the oscillations of a massive load on a planar statically definable symmetric truss of a regular type with parallel belts. Truss weight is not included. Free vertical oscillations are considered. The stiffness of the truss rods is assumed to be the same, the deformations are elastic. Lattice of the truss is double with descending braces and racks. New in the formulation and solution of the problem is the analytical form of the solution, which makes it possible in practice to easily evaluate the frequency characteristics of the structure depending on an arbitrary number of truss panels and the location of the load. Materials and methods. The operators and methods of the system of computer mathematics Maple are used. To determine the forces in the rods, the knotting method is used. The common terms of the sequence of coefficients of solutions for different numbers of panels are obtained from solving linear homogeneous recurrent equations of various order, obtained by special operators of the Maple system. Dependence on two arbitrary natural parameters is revealed in two stages. First, solutions for fixed load positions are found, then these solutions are summarized into one final formula for frequency. Results. By a series of individual solutions to the problem of load oscillation using the double induction method, it was possible to find common members of all sequences. The solution is polynomial in both natural parameters. Graphs constructed for particular cases, showed the adequacy of the approach. The discontinuous non-monotonic nature of the intermittent change depending on the number of truss panels and some other features of the solution are noted. Conclusions. It is shown that the induction method, previously applicable mainly to statics problems with one parameter (number of truss panels), is fully operational to the problems of the oscillations of system with two natural parameters. It should be noted that significant labor costs and a significant increase in the time symbolic transformations in such tasks","PeriodicalId":22024,"journal":{"name":"Stroitel stvo nauka i obrazovanie [Construction Science and Education]","volume":"141 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80298862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.22227/10.22227/2305-5502.2018.4.2
Victor A. Esinovsky, M. Sainov, B. A. Zaitsev, Sergey Filippov
Introduction. New building codes provide for a significant increase in the magnitude of seismic loads that should be perceived by hydraulic structures. In this regard, even in areas with low seismic activity, there may be a problem of ensuring the seismic stability of hydraulic structures. This is particularly acute in berthing facilities. As a rule, they are not so massive to withstand seismic loads. The issue of seismic stability of berthing facilities has not yet been properly considered. The results of numerical simulation of the seismic stability of the mooring-dividing wall during a 7-point earthquake are considered. A structure about 24 m high located on a non-rock base was investigated. Materials and methods. The seismic stability of the mooring structure was estimated by calculating its stress-strain state under the action of seismic forces. Calculations were carried out by the finite element method. Seismic loads on the structure were determined in two ways — by linear-spectral theory and by dynamic theory. For the calculation of seismic loads, 30 lower frequencies and the natural mode of the structure were determined together with an array of its base. When calculating according to the dynamic theory, the seismic effect was specified in the form of an accelerogram adopted for similar conditions. The direction of seismic impact was assumed horizontal. Results. According to the dynamic theory, seismic loads turned out to be lower than according to linear-spectral theory. However, the results of the calculation of the stress-strain state of the mooring structure were close. It was found that the seismic forces on the mooring wall will reach about a quarter of the weight of the structure. Under the influence of such forces, the mooring wall will lose its stability. Conclusions. To ensure seismic stability, it is recommended to combine the mooring wall and the base plate into a single monolithic structure, as well as to strengthen the lower part of the structure and facilitate the upper one.
{"title":"SEISMIC STABILITY OF THE MOORING WALL ACCORDING TO THE RESULTS OF NUMERICAL SIMULATION","authors":"Victor A. Esinovsky, M. Sainov, B. A. Zaitsev, Sergey Filippov","doi":"10.22227/10.22227/2305-5502.2018.4.2","DOIUrl":"https://doi.org/10.22227/10.22227/2305-5502.2018.4.2","url":null,"abstract":"Introduction. New building codes provide for a significant increase in the magnitude of seismic loads that should be perceived by hydraulic structures. In this regard, even in areas with low seismic activity, there may be a problem of ensuring the seismic stability of hydraulic structures. This is particularly acute in berthing facilities. As a rule, they are not so massive to withstand seismic loads. The issue of seismic stability of berthing facilities has not yet been properly considered. The results of numerical simulation of the seismic stability of the mooring-dividing wall during a 7-point earthquake are considered. A structure about 24 m high located on a non-rock base was investigated. Materials and methods. The seismic stability of the mooring structure was estimated by calculating its stress-strain state under the action of seismic forces. Calculations were carried out by the finite element method. Seismic loads on the structure were determined in two ways — by linear-spectral theory and by dynamic theory. For the calculation of seismic loads, 30 lower frequencies and the natural mode of the structure were determined together with an array of its base. When calculating according to the dynamic theory, the seismic effect was specified in the form of an accelerogram adopted for similar conditions. The direction of seismic impact was assumed horizontal. Results. According to the dynamic theory, seismic loads turned out to be lower than according to linear-spectral theory. However, the results of the calculation of the stress-strain state of the mooring structure were close. It was found that the seismic forces on the mooring wall will reach about a quarter of the weight of the structure. Under the influence of such forces, the mooring wall will lose its stability. Conclusions. To ensure seismic stability, it is recommended to combine the mooring wall and the base plate into a single monolithic structure, as well as to strengthen the lower part of the structure and facilitate the upper one.","PeriodicalId":22024,"journal":{"name":"Stroitel stvo nauka i obrazovanie [Construction Science and Education]","volume":"420 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82436319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.22227/10.22227/2305-5502.2018.4.1
V. Utkin
Introduction. Friction pile reliability under the action of the central compressing force according to the Set of Rules 24.13330.2011 is calculated from the first group of the limit states — from the bearing capacity (using the pile material strength criteria and the foundation soil bearing capacity criterion) and from the second group of the limit states — from the pile load-deformation behaviour. Materials and methods. A method of calculating the friction pile reliability from the foundation soil bearing capacity is considered. Reliability appears as a quantitative measure of safety of a single pile operation. The foundation soil bearing capacity is accepted as a criterion for the pile operating capacity. The pile reliability analysis is based on the statistical information obtained during the preliminary pile testing with measuring the friction on the surface of the pile placed in the soil layers and the soil stress under the pile foot. The testing methods for obtaining the statistical information were well-known and used earlier to generate the lists of f-values and R-values in the Set of Rules 24.13330.2011. Each random parameter is measured at least three times. Results. The theory of analysis of the preliminary pile reliability in accordance with GOST 27751-2014 “Reliability of building structures and foundations” has been built on this statistical information. Reliability as the calculation result is represented by interval notation. The mathematical model of the limit state of the pile from the foundation soil bearing capacity has been borrowed from the Set of Rules. The connection (formula) between the length of the pile and the value of its reliability as a safety measure for its operation in the foundation soil has been established. Evaluation of the friction pile reliability corresponding to the characteristic value is carried out by calculation (trail-and-error method) from the mechanical properties of the soil and the load on the pile with the indication of the value of the length of the pile or the sum of the soil layers, each of the values in this case shall be not more than 2 m. The reliability analysis is described in the case studies set out in the article. Conclusions. Pile reliability analysis is based on the actual information about the pile operation in the foundation soil according to the current regulations of the Russian Federation, so the proposed method of the friction pile reliability analysis can be transferred into practice. It can also be used in the reliability calculation for other load-bearing elements, in the regulatory literature, and in the academic work of construction universities.
{"title":"FRICTION PILE RELIABILITY ANALYSIS WITH RESPECT TO THE FOUNDATION SOIL BEARING CAPACITY","authors":"V. Utkin","doi":"10.22227/10.22227/2305-5502.2018.4.1","DOIUrl":"https://doi.org/10.22227/10.22227/2305-5502.2018.4.1","url":null,"abstract":"Introduction. Friction pile reliability under the action of the central compressing force according to the Set of Rules 24.13330.2011 is calculated from the first group of the limit states — from the bearing capacity (using the pile material strength criteria and the foundation soil bearing capacity criterion) and from the second group of the limit states — from the pile load-deformation behaviour. Materials and methods. A method of calculating the friction pile reliability from the foundation soil bearing capacity is considered. Reliability appears as a quantitative measure of safety of a single pile operation. The foundation soil bearing capacity is accepted as a criterion for the pile operating capacity. The pile reliability analysis is based on the statistical information obtained during the preliminary pile testing with measuring the friction on the surface of the pile placed in the soil layers and the soil stress under the pile foot. The testing methods for obtaining the statistical information were well-known and used earlier to generate the lists of f-values and R-values in the Set of Rules 24.13330.2011. Each random parameter is measured at least three times. Results. The theory of analysis of the preliminary pile reliability in accordance with GOST 27751-2014 “Reliability of building structures and foundations” has been built on this statistical information. Reliability as the calculation result is represented by interval notation. The mathematical model of the limit state of the pile from the foundation soil bearing capacity has been borrowed from the Set of Rules. The connection (formula) between the length of the pile and the value of its reliability as a safety measure for its operation in the foundation soil has been established. Evaluation of the friction pile reliability corresponding to the characteristic value is carried out by calculation (trail-and-error method) from the mechanical properties of the soil and the load on the pile with the indication of the value of the length of the pile or the sum of the soil layers, each of the values in this case shall be not more than 2 m. The reliability analysis is described in the case studies set out in the article. Conclusions. Pile reliability analysis is based on the actual information about the pile operation in the foundation soil according to the current regulations of the Russian Federation, so the proposed method of the friction pile reliability analysis can be transferred into practice. It can also be used in the reliability calculation for other load-bearing elements, in the regulatory literature, and in the academic work of construction universities.","PeriodicalId":22024,"journal":{"name":"Stroitel stvo nauka i obrazovanie [Construction Science and Education]","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75951389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Rutkauskas, D. Nagrockienė, G. Skripkiūnas, A. Kičaitė, G. Girskas
Abstract The article analyses the reactivity level of aggregates from Lithuanian quarries and their effect on the alkali corrosion in mortars. The reactivity of aggregates was assessed according to Rilem Recommended Test Method: AAR-2. The hardened cement paste and cracked aggregate contact zones were tested by means of optical microscopy. Two gravel aggregates and one sand aggregate from Lithuanian quarries were selected for testing. The tests revealed that according to AAR 2 methodology fine and coarse aggregates from Lithuanian quarries shall be allocated to Group II, i.e. reactive aggregates. The expansion after 14 days exceeds 0.1 % in the case of fine aggregate, the average expansion after 14 days is 0.13 %, and in the case of coarse aggregates the average expansion ranges from 0.11 % to 0.12 %.
{"title":"Identification of Reactivity Level in Aggregates from Lithuanian Gravel Quarry","authors":"A. Rutkauskas, D. Nagrockienė, G. Skripkiūnas, A. Kičaitė, G. Girskas","doi":"10.2478/cons-2017-0008","DOIUrl":"https://doi.org/10.2478/cons-2017-0008","url":null,"abstract":"Abstract The article analyses the reactivity level of aggregates from Lithuanian quarries and their effect on the alkali corrosion in mortars. The reactivity of aggregates was assessed according to Rilem Recommended Test Method: AAR-2. The hardened cement paste and cracked aggregate contact zones were tested by means of optical microscopy. Two gravel aggregates and one sand aggregate from Lithuanian quarries were selected for testing. The tests revealed that according to AAR 2 methodology fine and coarse aggregates from Lithuanian quarries shall be allocated to Group II, i.e. reactive aggregates. The expansion after 14 days exceeds 0.1 % in the case of fine aggregate, the average expansion after 14 days is 0.13 %, and in the case of coarse aggregates the average expansion ranges from 0.11 % to 0.12 %.","PeriodicalId":22024,"journal":{"name":"Stroitel stvo nauka i obrazovanie [Construction Science and Education]","volume":"100 1","pages":"54 - 59"},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73618103","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The article aims to present a research into the impact of dosage and effectiveness of commonly used plasticizing admixtures. More specifically, it focuses on rheological properties of the cement pastes (yield stresses and plastic viscosities) of different testing times (from 0 min to 90 min after mixing). The following materials were used in the study: Portland cement CEM I 42.5 R, plasticizer P (ligno-sulphonates based), superplasticizer SP1 (modified acrylic polymer based), superplasticizer SP2 (polycarboxylate esters based) and water. Experiments were carried out using rotational rheometer Rheotest RN4.1 with coaxial cylinders. It was observed that larger dosage of SP1 (0.6–1.2 %) results in slower increase in plasticizing effects until the 90 min margin. In conclusion, from the start of mixing until the 90 min margin, the best plasticizing effect and its retention are achieved by superplasticizer SP2. Recommended SP2 dosage varies within the range of 0.6 % to 0.8 %.
{"title":"The Influence of Commonly Used Plasticizing Admixtures on the Plasticizing Effect of Cement Paste","authors":"M. Macijauskas, G. Girskas","doi":"10.2478/cons-2017-0004","DOIUrl":"https://doi.org/10.2478/cons-2017-0004","url":null,"abstract":"Abstract The article aims to present a research into the impact of dosage and effectiveness of commonly used plasticizing admixtures. More specifically, it focuses on rheological properties of the cement pastes (yield stresses and plastic viscosities) of different testing times (from 0 min to 90 min after mixing). The following materials were used in the study: Portland cement CEM I 42.5 R, plasticizer P (ligno-sulphonates based), superplasticizer SP1 (modified acrylic polymer based), superplasticizer SP2 (polycarboxylate esters based) and water. Experiments were carried out using rotational rheometer Rheotest RN4.1 with coaxial cylinders. It was observed that larger dosage of SP1 (0.6–1.2 %) results in slower increase in plasticizing effects until the 90 min margin. In conclusion, from the start of mixing until the 90 min margin, the best plasticizing effect and its retention are achieved by superplasticizer SP2. Recommended SP2 dosage varies within the range of 0.6 % to 0.8 %.","PeriodicalId":22024,"journal":{"name":"Stroitel stvo nauka i obrazovanie [Construction Science and Education]","volume":"2 1","pages":"26 - 32"},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88485568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The article presents research results on a thermal insulation material made of low-moor peat. A model based on three components, including peat binder, frame component (wooden aggregate) and additives, was developed in the framework of this study. The conducted research showed that by grinding low-moor peat in water until the particle size is 2–5 mkm increased peat cohesion strength with wooden aggregate 2.5 to 2.7 times as well as increased the compressive strength of peat binder 5.0 to 5.5 times. Optimal parameters of strength and density in the wood peat composition with discontinuous granulometry wooden aggregate were achieved by using two fraction wood filler with fractions 2.5 mm ... 1.25 mm and 0.63 mm ... 0.315 mm in the proportion 50:50 and 60:40. Introducing anionic surfactants and foam forming non-ionic surfactants with neutral reaction against the surface of the peat and wood filler allows to reduce the average density up to 210–220 kg/m3, thus maintaining the required strength, and to reduce the coefficient of thermal conduction to 0.046 W/mK.
{"title":"The Development of Peat and Wood-Based Thermal Insulation Material Production Technology","authors":"T. Vasiljeva, A. Korjakins","doi":"10.2478/cons-2017-0009","DOIUrl":"https://doi.org/10.2478/cons-2017-0009","url":null,"abstract":"Abstract The article presents research results on a thermal insulation material made of low-moor peat. A model based on three components, including peat binder, frame component (wooden aggregate) and additives, was developed in the framework of this study. The conducted research showed that by grinding low-moor peat in water until the particle size is 2–5 mkm increased peat cohesion strength with wooden aggregate 2.5 to 2.7 times as well as increased the compressive strength of peat binder 5.0 to 5.5 times. Optimal parameters of strength and density in the wood peat composition with discontinuous granulometry wooden aggregate were achieved by using two fraction wood filler with fractions 2.5 mm ... 1.25 mm and 0.63 mm ... 0.315 mm in the proportion 50:50 and 60:40. Introducing anionic surfactants and foam forming non-ionic surfactants with neutral reaction against the surface of the peat and wood filler allows to reduce the average density up to 210–220 kg/m3, thus maintaining the required strength, and to reduce the coefficient of thermal conduction to 0.046 W/mK.","PeriodicalId":22024,"journal":{"name":"Stroitel stvo nauka i obrazovanie [Construction Science and Education]","volume":"48 1","pages":"60 - 67"},"PeriodicalIF":0.0,"publicationDate":"2017-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77791832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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