Pub Date : 2023-12-17DOI: 10.37538/2224-9494-2023-4(39)-120-131
A. G. Alekseev, P. Sazonov, S. P. Sorokina
Introduction. The drilling method of pile driving represents the most common method of constructing foundations on permafrost soils. In order to reduce the tangential forces of frost heaving, the space between the pile surface and a leader well wall within the layer of seasonal freezing-thawing is filled with non-heaving sandy soil. This technology complicates the process of installing driven precast piles. In this case, a significant simplification involves filling the space between the pile and the soil with a cement-sand mortar (CSM) along the entire height of the pile. However, at present, no method is valid for calculating driven precast piles for the action of frost heaving tangential forces during CSM freezing.Aim. To develop a methodology for calculating driven precast piles for the action of frost heaving tangential forces during CSM freezing.Materials and methods. A set of laboratory tests, modeling the processes in soils during cold and warm pile installation periods, was carried out. Laboratory tests were performed using a method of a single-plane cut along the surface of a CSM freezing with clay soils, as well as with the foundation material at a constant rate in accordance with State Standard R 56726-2015 and statistical data processing according to State Standard 20522-2012.Results. The article presents the results of laboratory studies on effects, caused by frost heaving tangential forces on piles during soil and CSM freezing, taking into account various factors (clay soil liquidity index, test temperature). Based on the obtained data, the authors propose a methodology for calculating the stability of driven precast piles. The method consists in determining the heaving force per unit area by adding the products of the seasonal freezing-thawing fractional depth, obtained by thermal engineering calculations or according to the plots, given in the article, by the tangential forces of frost heaving, obtained in laboratory studies.Conclusions. The developed methodology improves the reliability and accuracy of foundation calculations, enhances the efficiency of base and foundation design solutions, and reduces the labor capacity of driven precast pile installation.
{"title":"Frost soil interaction with the cement-sand mortar of a driven precast pile","authors":"A. G. Alekseev, P. Sazonov, S. P. Sorokina","doi":"10.37538/2224-9494-2023-4(39)-120-131","DOIUrl":"https://doi.org/10.37538/2224-9494-2023-4(39)-120-131","url":null,"abstract":"Introduction. The drilling method of pile driving represents the most common method of constructing foundations on permafrost soils. In order to reduce the tangential forces of frost heaving, the space between the pile surface and a leader well wall within the layer of seasonal freezing-thawing is filled with non-heaving sandy soil. This technology complicates the process of installing driven precast piles. In this case, a significant simplification involves filling the space between the pile and the soil with a cement-sand mortar (CSM) along the entire height of the pile. However, at present, no method is valid for calculating driven precast piles for the action of frost heaving tangential forces during CSM freezing.Aim. To develop a methodology for calculating driven precast piles for the action of frost heaving tangential forces during CSM freezing.Materials and methods. A set of laboratory tests, modeling the processes in soils during cold and warm pile installation periods, was carried out. Laboratory tests were performed using a method of a single-plane cut along the surface of a CSM freezing with clay soils, as well as with the foundation material at a constant rate in accordance with State Standard R 56726-2015 and statistical data processing according to State Standard 20522-2012.Results. The article presents the results of laboratory studies on effects, caused by frost heaving tangential forces on piles during soil and CSM freezing, taking into account various factors (clay soil liquidity index, test temperature). Based on the obtained data, the authors propose a methodology for calculating the stability of driven precast piles. The method consists in determining the heaving force per unit area by adding the products of the seasonal freezing-thawing fractional depth, obtained by thermal engineering calculations or according to the plots, given in the article, by the tangential forces of frost heaving, obtained in laboratory studies.Conclusions. The developed methodology improves the reliability and accuracy of foundation calculations, enhances the efficiency of base and foundation design solutions, and reduces the labor capacity of driven precast pile installation.","PeriodicalId":169749,"journal":{"name":"Bulletin of Science and Research Center of Construction","volume":"9 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138966229","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 : 2023-12-17DOI: 10.37538/2224-9494-2023-4(39)-132-142
B. S. Sokolov, V. A. Titaev, V. A. Neshchadimov
Introduction. For 38 years since the introduction of State Standard 21924.X-84, the regulatory framework for the design and manufacturing of reinforced concrete products has been significantly adjusted and supplemented. In this regard, the authors of the present article have developed an updated interstate standard for reinforced concrete slabs of city road pavements, taking into account amendments in the regulatory literature.Aim. To justify State Standard 21924.X-84 updating and present the updated State Standard 21924-2023 to specialists in the design of city roads and production of reinforced concrete slabs for city roads.Materials and methods. The analysis of existing regulatory documents and materials of contemporary studies in the field of materials science and road slab design was carried out. The authors provided the information on the updated interstate standard State Standard 21924-2023 “Reinforced concrete slabs for pavements of city roads. Specifications”, which specifies the rules and requirements for the design, testing and manufacturing technology of reinforced concrete slabs for city road pavements.Results. The performed revision toughen the requirements for concrete, expanded the range of selecting the steel for the road slab reinforcement in accordance with State Standard 34028, and brought the road slab loads in line with the current State Standard 32960. All four State Standards editions are combined into one document. Reinforcing materials, reinforcement specifications, as well as instructions for the design of reinforcement products were removed from the previous edition. The calculation and design of reinforcement elements is delegated to design organizations, which will develop solutions for the slab reinforcement based on relevant interstate and national regulatory documents.Conclusion. The updated standard specifies the technical requirements and test methods, acceptance rules and monitoring methods, which improves the quality of precast reinforced concrete slabs for city road pavements and significantly increases their durability.
{"title":"On the revision of the “Reinforced concrete slabs for pavements of city roads” interstate standard","authors":"B. S. Sokolov, V. A. Titaev, V. A. Neshchadimov","doi":"10.37538/2224-9494-2023-4(39)-132-142","DOIUrl":"https://doi.org/10.37538/2224-9494-2023-4(39)-132-142","url":null,"abstract":"Introduction. For 38 years since the introduction of State Standard 21924.X-84, the regulatory framework for the design and manufacturing of reinforced concrete products has been significantly adjusted and supplemented. In this regard, the authors of the present article have developed an updated interstate standard for reinforced concrete slabs of city road pavements, taking into account amendments in the regulatory literature.Aim. To justify State Standard 21924.X-84 updating and present the updated State Standard 21924-2023 to specialists in the design of city roads and production of reinforced concrete slabs for city roads.Materials and methods. The analysis of existing regulatory documents and materials of contemporary studies in the field of materials science and road slab design was carried out. The authors provided the information on the updated interstate standard State Standard 21924-2023 “Reinforced concrete slabs for pavements of city roads. Specifications”, which specifies the rules and requirements for the design, testing and manufacturing technology of reinforced concrete slabs for city road pavements.Results. The performed revision toughen the requirements for concrete, expanded the range of selecting the steel for the road slab reinforcement in accordance with State Standard 34028, and brought the road slab loads in line with the current State Standard 32960. All four State Standards editions are combined into one document. Reinforcing materials, reinforcement specifications, as well as instructions for the design of reinforcement products were removed from the previous edition. The calculation and design of reinforcement elements is delegated to design organizations, which will develop solutions for the slab reinforcement based on relevant interstate and national regulatory documents.Conclusion. The updated standard specifies the technical requirements and test methods, acceptance rules and monitoring methods, which improves the quality of precast reinforced concrete slabs for city road pavements and significantly increases their durability.","PeriodicalId":169749,"journal":{"name":"Bulletin of Science and Research Center of Construction","volume":"349 13","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138966687","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 : 2023-12-17DOI: 10.37538/2224-9494-2023-4(39)-68-81
K. Kudyakov, A. Buchkin, E. Yurin, S. K. Khlebnikov, V. A. Pentykhova
Introduction. In contrast to steel reinforcement, high tensile strength and relatively low elasticity modulus of fiber reinforced polymer rebar (FRP) determine the feasibility of its prestressing. However, the issues of its prestressing technology and the design of structures with its application are insufficiently studied. The current regulatory documentation contain no exhaustive scope of provisions and requirements in relation to the conditions and parameters of FRP prestressing and their account in the design and calculation of structures. In this regard, conducting a set of clarifying studies on this topic appears to be relevant and represents a considerable practical interest.Aim. To assess the effect of various FRP prestressing parameters on the stiffness and crack resistance of bending concrete elements.Materials and methods. As a part of the study, an experimental research program was developed and implemented, including the manufacture and bending testing of six concrete sample series with various FRP prestressing parameters.Results. The destructive loads were determined; patterns of deformation, cracking and destruction of bending concrete elements for various FRP prestressing parameters were established. The prerequisites for improving the system of urban planning activities in terms of clarifying and supplementing the existing regulatory documents for the design of FRP-reinforced concrete structures were established.Conclusion. The technology of FRP mechanical tensioning was laboratory successfully tested. Nevertheless, an adaptation of tensioning devices and grippers is required for its implementation at contemporary production enterprises. FRP prestressing was concluded to be an effective way of increasing the crack resistance and stiffness of bending concrete elements. Within the framework of the study, increase in the time of crack formation (relative to structures without prestressing) and a decrease in deflections in the middle of the span of up to 2.25 and 0.5 times, respectively, was recorded.
{"title":"Effects of prestress parameters of fiber reinforced polymer rebar on the stiffness and crack resistance of bending concrete elements. Experimental studies","authors":"K. Kudyakov, A. Buchkin, E. Yurin, S. K. Khlebnikov, V. A. Pentykhova","doi":"10.37538/2224-9494-2023-4(39)-68-81","DOIUrl":"https://doi.org/10.37538/2224-9494-2023-4(39)-68-81","url":null,"abstract":"Introduction. In contrast to steel reinforcement, high tensile strength and relatively low elasticity modulus of fiber reinforced polymer rebar (FRP) determine the feasibility of its prestressing. However, the issues of its prestressing technology and the design of structures with its application are insufficiently studied. The current regulatory documentation contain no exhaustive scope of provisions and requirements in relation to the conditions and parameters of FRP prestressing and their account in the design and calculation of structures. In this regard, conducting a set of clarifying studies on this topic appears to be relevant and represents a considerable practical interest.Aim. To assess the effect of various FRP prestressing parameters on the stiffness and crack resistance of bending concrete elements.Materials and methods. As a part of the study, an experimental research program was developed and implemented, including the manufacture and bending testing of six concrete sample series with various FRP prestressing parameters.Results. The destructive loads were determined; patterns of deformation, cracking and destruction of bending concrete elements for various FRP prestressing parameters were established. The prerequisites for improving the system of urban planning activities in terms of clarifying and supplementing the existing regulatory documents for the design of FRP-reinforced concrete structures were established.Conclusion. The technology of FRP mechanical tensioning was laboratory successfully tested. Nevertheless, an adaptation of tensioning devices and grippers is required for its implementation at contemporary production enterprises. FRP prestressing was concluded to be an effective way of increasing the crack resistance and stiffness of bending concrete elements. Within the framework of the study, increase in the time of crack formation (relative to structures without prestressing) and a decrease in deflections in the middle of the span of up to 2.25 and 0.5 times, respectively, was recorded.","PeriodicalId":169749,"journal":{"name":"Bulletin of Science and Research Center of Construction","volume":"2 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138966479","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 : 2023-12-17DOI: 10.37538/2224-9494-2023-4(39)-28-38
S. A. Zenin, O. V. Kudinov, K. Kudyakov, E. Yurin, S. K. Khlebnikov
Introduction. The current RF regulatory documentation contains only general instructions on the structural requirements for loop reinforcement joints in reinforced concrete structures without accounting their influence on the bearing capacity of normal sections, in particular, eccentrically compressed elements. These circumstances limit designers and may have a negative effect on the reliability of design solutions. In this regard, it seems necessary to investigate various possible structural options of loop joints and experimentally check their effect on the normal section strength of eccentrically compressed elements under static loads.Aim. To conduct experimental studies of the bearing capacity for normal sections of eccentrically compressed reinforced concrete elements with various options of loop reinforcement joints.Materials and methods. Experimental studies were carried out by testing reinforced concrete elements under an eccentrically applied static compressive load, taken into account the requirements of the current regulations. Results. The result of the studies involve experimental data on the normal section strength of eccentrically compressed reinforced concrete elements with various options of loop reinforcement joints, as well as data on their stiffness and crack resistance.Conclusion. According to the results of experimental studies, destructive loads, cracking patterns, and deflections of test samples were determined. For all eccentrically compressed samples with loop joints, the strength of normal sections is lower by 3–12 % than the strength of control samples without reinforcement joints. This reveals a tendency of a bearing capacity to increase as the length of the straight insert at the joint, as well as the area of the transverse reinforcement in the joint area, increases. Further, a more detailed publication of the obtained experimental data is planned.
{"title":"Normal section strength of eccentrically compressed reinforced concrete structures with loop reinforcement joints. Experimental studies","authors":"S. A. Zenin, O. V. Kudinov, K. Kudyakov, E. Yurin, S. K. Khlebnikov","doi":"10.37538/2224-9494-2023-4(39)-28-38","DOIUrl":"https://doi.org/10.37538/2224-9494-2023-4(39)-28-38","url":null,"abstract":"Introduction. The current RF regulatory documentation contains only general instructions on the structural requirements for loop reinforcement joints in reinforced concrete structures without accounting their influence on the bearing capacity of normal sections, in particular, eccentrically compressed elements. These circumstances limit designers and may have a negative effect on the reliability of design solutions. In this regard, it seems necessary to investigate various possible structural options of loop joints and experimentally check their effect on the normal section strength of eccentrically compressed elements under static loads.Aim. To conduct experimental studies of the bearing capacity for normal sections of eccentrically compressed reinforced concrete elements with various options of loop reinforcement joints.Materials and methods. Experimental studies were carried out by testing reinforced concrete elements under an eccentrically applied static compressive load, taken into account the requirements of the current regulations. Results. The result of the studies involve experimental data on the normal section strength of eccentrically compressed reinforced concrete elements with various options of loop reinforcement joints, as well as data on their stiffness and crack resistance.Conclusion. According to the results of experimental studies, destructive loads, cracking patterns, and deflections of test samples were determined. For all eccentrically compressed samples with loop joints, the strength of normal sections is lower by 3–12 % than the strength of control samples without reinforcement joints. This reveals a tendency of a bearing capacity to increase as the length of the straight insert at the joint, as well as the area of the transverse reinforcement in the joint area, increases. Further, a more detailed publication of the obtained experimental data is planned.","PeriodicalId":169749,"journal":{"name":"Bulletin of Science and Research Center of Construction","volume":"26 27","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138966079","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 : 2023-12-17DOI: 10.37538/2224-9494-2023-4(39)-82-94
O. I. Ponomarev, Yu. F. Panchenko, M. A. Mukhin, A. S. Vetkov, A. Y. Dozorova
Introduction. State standards for testing ceramic masonry wall materials of plastic molding establish grinding as the main method of smoothening supporting (loaded) surfaces. Therefore, studies were conducted on the effect of sample dimensions on the compressive strength of tested masonry products. The effect of a scale factor on the measured strength of brick and stone has so far been only partially reflected in the standard for test methods (GOST 8462 “Wall materials. Methods for determining compressive and bending strength”). According to both Russian and foreign specialists, shape factors values, provided in EN 772-1 European standard “Methods of test for masonry units. Part 1. Determination of compressive strength” need to be adjusted as they do not take into account the void ratio of masonry products and the sample material type.Aim. To assess the effects, caused by the geometric dimensions of masonry product samples, as well as the void ratio and other characteristics, on compressive strength according to the results of laboratory tests. Materials and methods. As a result of conducted control tests of ceramic and silicate single and thickened bricks with a void ratio of up to 27 %, measured values of product compression strength were compared to determine the value of transition coefficients.Results. The performed studies confirmed the shape coefficients, adopted in EN 772-1, to require an adjustment. Based on the results of studies, conducted in Russia and abroad, conclusions and recommendations were made to take into account the dimensions of tested samples during strength tests.Conclusion. Performed studies and analysis of experimental results have demonstrated that in order to increase the accuracy of determining the strength of test samples, taking into account their shape and void ratio, it is necessary to have several tables with shape factors. Currently, until reliable data about the void ratio effect of the masonry material on test results are obtained, it is advisable to take into account only the height of the sample (“longitudinal bending”).
{"title":"Effects of sample dimensions in compressive strength tests of masonry wall products","authors":"O. I. Ponomarev, Yu. F. Panchenko, M. A. Mukhin, A. S. Vetkov, A. Y. Dozorova","doi":"10.37538/2224-9494-2023-4(39)-82-94","DOIUrl":"https://doi.org/10.37538/2224-9494-2023-4(39)-82-94","url":null,"abstract":"Introduction. State standards for testing ceramic masonry wall materials of plastic molding establish grinding as the main method of smoothening supporting (loaded) surfaces. Therefore, studies were conducted on the effect of sample dimensions on the compressive strength of tested masonry products. The effect of a scale factor on the measured strength of brick and stone has so far been only partially reflected in the standard for test methods (GOST 8462 “Wall materials. Methods for determining compressive and bending strength”). According to both Russian and foreign specialists, shape factors values, provided in EN 772-1 European standard “Methods of test for masonry units. Part 1. Determination of compressive strength” need to be adjusted as they do not take into account the void ratio of masonry products and the sample material type.Aim. To assess the effects, caused by the geometric dimensions of masonry product samples, as well as the void ratio and other characteristics, on compressive strength according to the results of laboratory tests. Materials and methods. As a result of conducted control tests of ceramic and silicate single and thickened bricks with a void ratio of up to 27 %, measured values of product compression strength were compared to determine the value of transition coefficients.Results. The performed studies confirmed the shape coefficients, adopted in EN 772-1, to require an adjustment. Based on the results of studies, conducted in Russia and abroad, conclusions and recommendations were made to take into account the dimensions of tested samples during strength tests.Conclusion. Performed studies and analysis of experimental results have demonstrated that in order to increase the accuracy of determining the strength of test samples, taking into account their shape and void ratio, it is necessary to have several tables with shape factors. Currently, until reliable data about the void ratio effect of the masonry material on test results are obtained, it is advisable to take into account only the height of the sample (“longitudinal bending”).","PeriodicalId":169749,"journal":{"name":"Bulletin of Science and Research Center of Construction","volume":"10 18","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138966191","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 : 2023-12-17DOI: 10.37538/2224-9494-2023-4(39)-39-52
V. A. Komarov, S. N. Laskov
Introduction. Half-precast frames embodied the positive properties of both precast and cast-in-situ structures. These structural systems are difficult to introduce due to their low level of knowledge, lack of experimental data, and an almost complete absence of a regulatory and technical framework for a design. This stimulates a need to improve and develop new joints with high operational reliability and manufacturability.Aim. To identify the causes of the frame joint destruction.Materials and methods. The frame joint is provided by the hidden cast-in-situ column cantilever in the grooves of crossbars and half-precast floor slab with the installation of additional longitudinal and transverse reinforcement. Precast and cast-in-situ elements interact mainly by reinforcement starter bars. The destruction of frame joints was considered using the example of a half-precast frame with the main spans of 9 and 12 m in a two-storey building according to the results of a full-scale survey during the construction period.Results. At the joints of most crossbars with columns, inclined cracks were detected in the support zones along the lateral surfaces with an opening width of 0.1–5 mm. In addition, cracks were observed along the contact area of the support crossbar groove with the column grouting concrete. An opening revealed them spreading into the body of the groove grouting concrete along the column edge. No adhesion between the walls of a crossbar groove with the joint grouting concrete is observed. The crack formation pattern indicates the determined contour of the floor slab punching above the column.Conclusion. The cause for the destruction of half-precast frame joints involves the insufficient bearing capacity of the section for the action of transverse forces due to the ductility of precast and cast-in-situ elements.
{"title":"Half-precast “crossbar-slab-column” frame joint","authors":"V. A. Komarov, S. N. Laskov","doi":"10.37538/2224-9494-2023-4(39)-39-52","DOIUrl":"https://doi.org/10.37538/2224-9494-2023-4(39)-39-52","url":null,"abstract":"Introduction. Half-precast frames embodied the positive properties of both precast and cast-in-situ structures. These structural systems are difficult to introduce due to their low level of knowledge, lack of experimental data, and an almost complete absence of a regulatory and technical framework for a design. This stimulates a need to improve and develop new joints with high operational reliability and manufacturability.Aim. To identify the causes of the frame joint destruction.Materials and methods. The frame joint is provided by the hidden cast-in-situ column cantilever in the grooves of crossbars and half-precast floor slab with the installation of additional longitudinal and transverse reinforcement. Precast and cast-in-situ elements interact mainly by reinforcement starter bars. The destruction of frame joints was considered using the example of a half-precast frame with the main spans of 9 and 12 m in a two-storey building according to the results of a full-scale survey during the construction period.Results. At the joints of most crossbars with columns, inclined cracks were detected in the support zones along the lateral surfaces with an opening width of 0.1–5 mm. In addition, cracks were observed along the contact area of the support crossbar groove with the column grouting concrete. An opening revealed them spreading into the body of the groove grouting concrete along the column edge. No adhesion between the walls of a crossbar groove with the joint grouting concrete is observed. The crack formation pattern indicates the determined contour of the floor slab punching above the column.Conclusion. The cause for the destruction of half-precast frame joints involves the insufficient bearing capacity of the section for the action of transverse forces due to the ductility of precast and cast-in-situ elements.","PeriodicalId":169749,"journal":{"name":"Bulletin of Science and Research Center of Construction","volume":"26 15","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138965852","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 : 2023-12-17DOI: 10.37538/2224-9494-2023-4(39)-57-67
M. A. Komarova, I. A. Grishin, M. V. Shalabin, A. N. Strekalev, N. O. Melnikov
Introduction. Due to the increasing popularity of timber housing construction, new timber structures with unstudied properties appear provided with no fire safety standards of their use.Aim: to obtain data on fire resistance and fire hazard of combined metal-timber structures, used in floors of residential and public buildings.Materials and methods. In the study, a fragment of a combined metal-timber floor structure with a size of 4300 × 2000 mm and a thickness of 160 mm was tested using the methods for determining fire resistance and fire hazard classes.Results. According to the test results, uncoated samples under a vertical uniformly distributed load of 520 kg/m2 were classified as REI 60, while the Evrika fire retardant, applied to samples from the outside at a consumption of 500 g/m2, has improved their fire resistance to REI 90. The fire hazard class of uncoated samples and coated with fire retardants corresponds to K3(15) and K0(15), respectively.Conclusion. New experimental data will be used in the preparation of amendments to SP 64.13330.2017 “SNiP II-25-80 Timber Structures” for ensuring regulatory fire safety requirements to these structures.
{"title":"Fire resistance and fire hazard study of combined metal-timber structures","authors":"M. A. Komarova, I. A. Grishin, M. V. Shalabin, A. N. Strekalev, N. O. Melnikov","doi":"10.37538/2224-9494-2023-4(39)-57-67","DOIUrl":"https://doi.org/10.37538/2224-9494-2023-4(39)-57-67","url":null,"abstract":"Introduction. Due to the increasing popularity of timber housing construction, new timber structures with unstudied properties appear provided with no fire safety standards of their use.Aim: to obtain data on fire resistance and fire hazard of combined metal-timber structures, used in floors of residential and public buildings.Materials and methods. In the study, a fragment of a combined metal-timber floor structure with a size of 4300 × 2000 mm and a thickness of 160 mm was tested using the methods for determining fire resistance and fire hazard classes.Results. According to the test results, uncoated samples under a vertical uniformly distributed load of 520 kg/m2 were classified as REI 60, while the Evrika fire retardant, applied to samples from the outside at a consumption of 500 g/m2, has improved their fire resistance to REI 90. The fire hazard class of uncoated samples and coated with fire retardants corresponds to K3(15) and K0(15), respectively.Conclusion. New experimental data will be used in the preparation of amendments to SP 64.13330.2017 “SNiP II-25-80 Timber Structures” for ensuring regulatory fire safety requirements to these structures.","PeriodicalId":169749,"journal":{"name":"Bulletin of Science and Research Center of Construction","volume":"2 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138966481","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 : 2023-12-17DOI: 10.37538/2224-9494-2023-4(39)-106-119
M. Farfel, S. V. Gurov, O. V. Glazunov
Introduction. The article presents a new method of reinforcing field welds with defects, impermissible according to the regulation requirements. This method allows reinforcement works to be carried out while maintaining the functional purpose of a building or structure without closing for the repair.Aim. To develop a technology of reinforcing defective welds, which preserves the functional purpose of a structure during repair works without its closure.Materials and methods. Reinforcement is carried out using a sheet of high-strength steel. The reinforcing sheet must be attached to connected field elements, which excludes the defective weld from the operation. Welders are permitted to perform works after testing on control welded joints. Welds, made by a candidate welder, is cut and sent to a specialized laboratory for determining weld strength properties, impact strength of weld macro- and microstructures, as well as the order and dimensions of legs for multi-pass welds. If the obtained weld data meets the standard indicators, the candidate welder is permitted to connect the reinforcement sheets of defective field welds. After making welded joints, they must be checked by visual, instrumental and ultrasonic testing.Results. A method of reinforcing defective welds was developed and implemented. Defects in the welds appeared during the connection of field elements, whose dimensions were less than the transport size, into a single spatial system, for example, the inner contour of a dome cover. This type of reinforcement can be made without closing the building or structure for repair works.Conclusion. The method of weld reinforcement can be used to remedy impermissible derects, detected by visual, instrumental and ultrasonic testing, in any buildings and structures, including unique long-span ones, therefore ensuring their reliable and safe operation after the construction.
{"title":"Method of reinforcing defects in field welds of unique buildings and structures","authors":"M. Farfel, S. V. Gurov, O. V. Glazunov","doi":"10.37538/2224-9494-2023-4(39)-106-119","DOIUrl":"https://doi.org/10.37538/2224-9494-2023-4(39)-106-119","url":null,"abstract":"Introduction. The article presents a new method of reinforcing field welds with defects, impermissible according to the regulation requirements. This method allows reinforcement works to be carried out while maintaining the functional purpose of a building or structure without closing for the repair.Aim. To develop a technology of reinforcing defective welds, which preserves the functional purpose of a structure during repair works without its closure.Materials and methods. Reinforcement is carried out using a sheet of high-strength steel. The reinforcing sheet must be attached to connected field elements, which excludes the defective weld from the operation. Welders are permitted to perform works after testing on control welded joints. Welds, made by a candidate welder, is cut and sent to a specialized laboratory for determining weld strength properties, impact strength of weld macro- and microstructures, as well as the order and dimensions of legs for multi-pass welds. If the obtained weld data meets the standard indicators, the candidate welder is permitted to connect the reinforcement sheets of defective field welds. After making welded joints, they must be checked by visual, instrumental and ultrasonic testing.Results. A method of reinforcing defective welds was developed and implemented. Defects in the welds appeared during the connection of field elements, whose dimensions were less than the transport size, into a single spatial system, for example, the inner contour of a dome cover. This type of reinforcement can be made without closing the building or structure for repair works.Conclusion. The method of weld reinforcement can be used to remedy impermissible derects, detected by visual, instrumental and ultrasonic testing, in any buildings and structures, including unique long-span ones, therefore ensuring their reliable and safe operation after the construction.","PeriodicalId":169749,"journal":{"name":"Bulletin of Science and Research Center of Construction","volume":"5 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138965812","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 : 2023-12-17DOI: 10.37538/2224-9494-2023-4(39)-7-27
I. M. Garanzha, A. Tanasoglo, M. Pisareva
Introduction. Being indisputably relevant, an identification of the features of modeling tower structures can simplify the work of engineers and simultaneously move the design decision-making to a qualitatively new level.Aim. To assess the effect, caused by some particular features of a computational modelling, on the resulting parameter, representing the frequency behavior of a tubular tower for wind-power units.Materials and Methods. Numerical studies were conducted using a domestic SCAD Office programming and computing suite. In computational modeling, 41st, 42nd, 44th and 50th FE types were used. During the assessment of effects, caused by the finite element type, calculations of a cylindrical tower with fixed parameters were performed, taking into account variations in the type and size of the FE. Estimating factors in calculations included: variations in stresses, as well as in the frequency of first-mode natural oscillations. During the comparison of stress values, the plate of the third from the fixed base row was taken as the design one. Turbowind T600-48 and Eviag EV 100 were considered as wind turbines.Results. A sufficient discretization value of the computational model for determining the frequency of natural oscillations equals to nR = 12, since a further increase in the value of nR will lead to variations in the frequency of natural oscillations by less than 1%. The individual frequencies of 0.275 and 0.825 Hz were determined for an Eviag EV 100 wind turbine. For a Turbowind T600-48, the range of resonant frequencies is determined due to the presence of a variable rotor speed: starting and maximum frequency ranges of 0.255–0.765 and 0.383–1.149 Hz, respectively.Conclusions. During the modeling of a tower in the SCAD Office PCS, it is feasible to use the 44th type of finite elements, taking into account the obtained sufficient discretization value. The obtained spectrum of natural and resonant frequencies allows avoiding the appearance of a resonant effect when making design decisions.
导言。确定塔架结构建模的特征无疑具有重要意义，可以简化工程师的工作，同时将设计决策提升到一个新的水平。评估计算建模的某些特定特征对结果参数的影响，这些参数代表了风力发电装置管状塔架的频率行为。数值研究使用国内 SCAD Office 编程和计算套件进行。在计算建模过程中，使用了第 41、42、44 和 50 次 FE 类型。在评估有限元类型造成的影响时，考虑到有限元类型和尺寸的变化，对具有固定参数的圆柱形塔进行了计算。计算中的估算因素包括：应力的变化以及一模自然振荡频率的变化。在比较应力值时，将固定基座排第三块板作为设计板。Turbowind T600-48 和 Eviag EV 100 被视为风力涡轮机。计算模型的离散值足以确定自然振荡频率，即 nR = 12，因为进一步增加 nR 值将导致自然振荡频率的变化小于 1%。Eviag EV 100 风机的单个频率分别为 0.275 和 0.825 Hz。对于 Turbowind T600-48，由于存在可变转子速度，共振频率范围已确定：起始和最大频率范围分别为 0.255-0.765 和 0.383-1.149 Hz。在 SCAD Office PCS 中对塔架进行建模时，考虑到所获得的足够离散值，使用第 44 类有限元是可行的。所获得的固有频率和共振频率频谱可以在设计决策时避免出现共振效应。
{"title":"Features of a finite-element modeling of a tubular tower for a wind-power unit","authors":"I. M. Garanzha, A. Tanasoglo, M. Pisareva","doi":"10.37538/2224-9494-2023-4(39)-7-27","DOIUrl":"https://doi.org/10.37538/2224-9494-2023-4(39)-7-27","url":null,"abstract":"Introduction. Being indisputably relevant, an identification of the features of modeling tower structures can simplify the work of engineers and simultaneously move the design decision-making to a qualitatively new level.Aim. To assess the effect, caused by some particular features of a computational modelling, on the resulting parameter, representing the frequency behavior of a tubular tower for wind-power units.Materials and Methods. Numerical studies were conducted using a domestic SCAD Office programming and computing suite. In computational modeling, 41st, 42nd, 44th and 50th FE types were used. During the assessment of effects, caused by the finite element type, calculations of a cylindrical tower with fixed parameters were performed, taking into account variations in the type and size of the FE. Estimating factors in calculations included: variations in stresses, as well as in the frequency of first-mode natural oscillations. During the comparison of stress values, the plate of the third from the fixed base row was taken as the design one. Turbowind T600-48 and Eviag EV 100 were considered as wind turbines.Results. A sufficient discretization value of the computational model for determining the frequency of natural oscillations equals to nR = 12, since a further increase in the value of nR will lead to variations in the frequency of natural oscillations by less than 1%. The individual frequencies of 0.275 and 0.825 Hz were determined for an Eviag EV 100 wind turbine. For a Turbowind T600-48, the range of resonant frequencies is determined due to the presence of a variable rotor speed: starting and maximum frequency ranges of 0.255–0.765 and 0.383–1.149 Hz, respectively.Conclusions. During the modeling of a tower in the SCAD Office PCS, it is feasible to use the 44th type of finite elements, taking into account the obtained sufficient discretization value. The obtained spectrum of natural and resonant frequencies allows avoiding the appearance of a resonant effect when making design decisions.","PeriodicalId":169749,"journal":{"name":"Bulletin of Science and Research Center of Construction","volume":"17 13","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138965838","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 : 2023-12-17DOI: 10.37538/2224-9494-2023-4(39)-95-105
G. Tonkikh, V. A. Neshchadimov, I. A. Averin
Introduction. Statistical methods in the analysis of experimental data can be applied to identify patterns and test hypotheses, determine the quality of experimental data and draw conclusions based on objective data. In addition, experimental data after non-parametric processing can be used in numerical modeling using contemporary computing suites.Aim. To outline a methodology for non-parametric processing of experimental results using SCAD computing suite tools, certified in the territory of the Russian Federation. In the proposed methodology, experimental test data for spirally reinforced concrete samples of various strengths were used.Results. As a result of non-parametric processing of spirally reinforced concrete samples, empirical coefficients of the Prandtl bilinear diagram were determined according to the proposed method. This diagram is used in the SCAD computing suite to set the physical nonlinearity of the material behavior. A method for processing a small volume of experimental results is proposed for using the available data in SCAD CS numerical studies with an acceptable level of probability.Conclusions. The empirical coefficients, obtained in non-parametric processing for setting the Prandtl bilinear diagram, can be used to perform a numerical modeling of the sample bahavior for planning further experimental studies in order to find more general patterns, taking into account other behavioral factors of real structural elements in load-bearing systems of buildings and structures with spiral reinforcement, including high-intensity dynamic effects. According to experimental and theoretical studies, spiral reinforcement can significantly increase the deformability and energy capacity of reinforced concrete structures, which fundamentally affects the behavioral pattern of structures and supporting framework of buildings and structures as a whole. These behavioral features of spirally reinforced structures can be further taken into account for the computational justification of design solutions in the SCAD CS and other software programs using the Padé approximation of the Prandtl bilinear diagram.
{"title":"Non-parametric data processing in experimental studies of spirally reinforced concrete samples","authors":"G. Tonkikh, V. A. Neshchadimov, I. A. Averin","doi":"10.37538/2224-9494-2023-4(39)-95-105","DOIUrl":"https://doi.org/10.37538/2224-9494-2023-4(39)-95-105","url":null,"abstract":"Introduction. Statistical methods in the analysis of experimental data can be applied to identify patterns and test hypotheses, determine the quality of experimental data and draw conclusions based on objective data. In addition, experimental data after non-parametric processing can be used in numerical modeling using contemporary computing suites.Aim. To outline a methodology for non-parametric processing of experimental results using SCAD computing suite tools, certified in the territory of the Russian Federation. In the proposed methodology, experimental test data for spirally reinforced concrete samples of various strengths were used.Results. As a result of non-parametric processing of spirally reinforced concrete samples, empirical coefficients of the Prandtl bilinear diagram were determined according to the proposed method. This diagram is used in the SCAD computing suite to set the physical nonlinearity of the material behavior. A method for processing a small volume of experimental results is proposed for using the available data in SCAD CS numerical studies with an acceptable level of probability.Conclusions. The empirical coefficients, obtained in non-parametric processing for setting the Prandtl bilinear diagram, can be used to perform a numerical modeling of the sample bahavior for planning further experimental studies in order to find more general patterns, taking into account other behavioral factors of real structural elements in load-bearing systems of buildings and structures with spiral reinforcement, including high-intensity dynamic effects. According to experimental and theoretical studies, spiral reinforcement can significantly increase the deformability and energy capacity of reinforced concrete structures, which fundamentally affects the behavioral pattern of structures and supporting framework of buildings and structures as a whole. These behavioral features of spirally reinforced structures can be further taken into account for the computational justification of design solutions in the SCAD CS and other software programs using the Padé approximation of the Prandtl bilinear diagram.","PeriodicalId":169749,"journal":{"name":"Bulletin of Science and Research Center of Construction","volume":"7 23","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138966083","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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