Pub Date : 2023-07-01DOI: 10.31650/2707-3068-2023-27-59-66
Petro Homon
An undeniable disadvantage of wood when using it in construction is its excessive flexibility. One of the ways to increase the stiffness of wooden elements is to use prestressing and reinforcement with stiffer elements. The manufacturing process of pre-stressed bending elements proposed by us is simple. However, determining the necessary effort, the necessary bending of the beam to ensure reliable operation, preventing the destruction of the element is quite difficult. One of the methods of prestressing is described, namely, the method by which the beam receives internal stresses due to the release of the bending element after the action of the external load by gluing reinforced elements. The principle of such tension can be described in the following sequence: 1. We create a bend in the bending element by applying an external load to the element. 2. We reinforce the lower zone of the bending element. At the same time, we need to know under which stress-strained state the reinforced element was installed, so that its operation can be predicted. 3. We remove the applied force with which we created the bend in the flexible wooden element, while the element wants to acquire its original shape, but this will be prevented by the armature, which will absorb part of the load and leave a small bend. It was established that the level of prestressing, namely the curvature acquired by the bending element after prestressing, depends on the initial curvature of the wooden element, as well as on the area and physical and mechanical characteristics of the materials reinforcing the beam zones. To determine the prestress, it is necessary to establish the stress-deformed states of the bending element, which occur after gluing and release of the external force. At the same time, 3 levels of the stress-strain state can be distinguished. 1. At the first stage, the compressed zone is more than the stretched zone. The relative deformations of the compressed lower zone, where the material is to be attached, is the initial start for the work of the reinforced element. 2. At the second stage, the external bending moment decreases, the internal redistribution of forces takes place, in addition to the moment perceived by the compressed and stretched zone, a moment also occurs in the stretched reinforced element. 3. The third stage is characterized by the absence of an external load, and this causes a balance between the internal forces of the bending prestressed element. The equilibrium equation for three stages was obtained. When using the element as a load-bearing structure, the cross-section in the element can be with both positive and negative curvature. The peculiarities of these two stress-strain states are manifested in the change in the position of the compressed and stretched zones. In the first case, the compressed zone is located in the lower part of the element and the upper part is occupied by the stretched zone. After the curvature changes its sign from negati
{"title":"SIMULATION OF WORK OF A REINFORCED PRE-STRESSED WOODEN ELEMENT","authors":"Petro Homon","doi":"10.31650/2707-3068-2023-27-59-66","DOIUrl":"https://doi.org/10.31650/2707-3068-2023-27-59-66","url":null,"abstract":"An undeniable disadvantage of wood when using it in construction is its excessive flexibility. One of the ways to increase the stiffness of wooden elements is to use prestressing and reinforcement with stiffer elements. The manufacturing process of pre-stressed bending elements proposed by us is simple. However, determining the necessary effort, the necessary bending of the beam to ensure reliable operation, preventing the destruction of the element is quite difficult. One of the methods of prestressing is described, namely, the method by which the beam receives internal stresses due to the release of the bending element after the action of the external load by gluing reinforced elements. The principle of such tension can be described in the following sequence: 1. We create a bend in the bending element by applying an external load to the element. 2. We reinforce the lower zone of the bending element. At the same time, we need to know under which stress-strained state the reinforced element was installed, so that its operation can be predicted. 3. We remove the applied force with which we created the bend in the flexible wooden element, while the element wants to acquire its original shape, but this will be prevented by the armature, which will absorb part of the load and leave a small bend. It was established that the level of prestressing, namely the curvature acquired by the bending element after prestressing, depends on the initial curvature of the wooden element, as well as on the area and physical and mechanical characteristics of the materials reinforcing the beam zones. To determine the prestress, it is necessary to establish the stress-deformed states of the bending element, which occur after gluing and release of the external force. At the same time, 3 levels of the stress-strain state can be distinguished. 1. At the first stage, the compressed zone is more than the stretched zone. The relative deformations of the compressed lower zone, where the material is to be attached, is the initial start for the work of the reinforced element. 2. At the second stage, the external bending moment decreases, the internal redistribution of forces takes place, in addition to the moment perceived by the compressed and stretched zone, a moment also occurs in the stretched reinforced element. 3. The third stage is characterized by the absence of an external load, and this causes a balance between the internal forces of the bending prestressed element. The equilibrium equation for three stages was obtained. When using the element as a load-bearing structure, the cross-section in the element can be with both positive and negative curvature. The peculiarities of these two stress-strain states are manifested in the change in the position of the compressed and stretched zones. In the first case, the compressed zone is located in the lower part of the element and the upper part is occupied by the stretched zone. After the curvature changes its sign from negati","PeriodicalId":365885,"journal":{"name":"Modern structures of metal and wood","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128270637","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 : 2023-07-01DOI: 10.31650/2707-3068-2023-27-41-51
A. Wojnar, K. Marszałek, O. Chernieva, L. Ślęczka
The bolted joints in the leg and the bracing members of the lattice transmission towers are always subjected to predominant axial forces, which will cause joint slip that greatly affects the global be-haviour of the whole structure. The paper shows the results of the numerical modelling of the re-sponse of the steel lattice communication tower, with height h = 40.5 m located in Rzeszów. A comparison was made of five tower models, differing in the characteristics of the joint force-elongation relationship, including stiffness of the components and also joint slippage, coming from Category A joints. The paper presents the difference in displacements and rotations of chosen tower panels, internal forces in leg members, as well as in the fundamental flexural frequency obtained without considering the force-displacement characteristic and with four different ways of modelling of joints behaviour
{"title":"INFLUENCE OF BOLTED SPLICE CONNECTIONS ON THE GLOBAL BEHAVIOUR OF STEEL LATTICE TELECOMMUNICATION TOWERS","authors":"A. Wojnar, K. Marszałek, O. Chernieva, L. Ślęczka","doi":"10.31650/2707-3068-2023-27-41-51","DOIUrl":"https://doi.org/10.31650/2707-3068-2023-27-41-51","url":null,"abstract":"The bolted joints in the leg and the bracing members of the lattice transmission towers are always subjected to predominant axial forces, which will cause joint slip that greatly affects the global be-haviour of the whole structure. The paper shows the results of the numerical modelling of the re-sponse of the steel lattice communication tower, with height h = 40.5 m located in Rzeszów. A comparison was made of five tower models, differing in the characteristics of the joint force-elongation relationship, including stiffness of the components and also joint slippage, coming from Category A joints. The paper presents the difference in displacements and rotations of chosen tower panels, internal forces in leg members, as well as in the fundamental flexural frequency obtained without considering the force-displacement characteristic and with four different ways of modelling of joints behaviour","PeriodicalId":365885,"journal":{"name":"Modern structures of metal and wood","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125974575","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 : 2023-07-01DOI: 10.31650/2707-3068-2023-27-28-34
S. Shekhorkina, O. Zinkevych, Т.А. Kovtun-Horbachova, Y.V. Zhuk
The article presents the results of theoretical studies on embodied carbon for load-bearing wall structures prevailing in low-rise buildings consturction practice in order to reveal the potential of timber structures in decarbonization of the construction sector. Seven types of wall structures were considered in the study. CO2 emissions were determined using the environmental product declarations for relevant materials considering sequential life-cycle stages (raw material supply, production and transportation of building products, construction process, building waste transportation and disposal) with regard to recycling benefits. A lightweight timber framed wall panel was shown to have minimum carbon emissions at each life-cycle stage leading to lowest total carbon embodied
{"title":"REVEALING TIMBER STRUCTURES POTENTIAL IN DECARBONIZATION OF LOW-RISE RESIDENTIAL BUILDINGS","authors":"S. Shekhorkina, O. Zinkevych, Т.А. Kovtun-Horbachova, Y.V. Zhuk","doi":"10.31650/2707-3068-2023-27-28-34","DOIUrl":"https://doi.org/10.31650/2707-3068-2023-27-28-34","url":null,"abstract":"The article presents the results of theoretical studies on embodied carbon for load-bearing wall structures prevailing in low-rise buildings consturction practice in order to reveal the potential of timber structures in decarbonization of the construction sector. Seven types of wall structures were considered in the study. CO2 emissions were determined using the environmental product declarations for relevant materials considering sequential life-cycle stages (raw material supply, production and transportation of building products, construction process, building waste transportation and disposal) with regard to recycling benefits. A lightweight timber framed wall panel was shown to have minimum carbon emissions at each life-cycle stage leading to lowest total carbon embodied","PeriodicalId":365885,"journal":{"name":"Modern structures of metal and wood","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132426489","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 : 2023-07-01DOI: 10.31650/2707-3068-2023-27-94-103
S. Pichugin, V. V. Shulhin, K.O. Oksenenko
In the context of martial law, Ukraine's agricultural sector is suffering significant losses. By May 2022. Ukraine has already lost almost 13 million tonnes of elevator capacity, some of the grain warehouses have been completely destroyed, and some are in the occupied territories. In this regard, there is a need for elevator capacities, namely, prefabricated, cost-efficient storage capacities. Such structures are exemplified by silos. There are many design solutions for metal silos. However, the rising cost of materials is causing a need to reduce the material intensity of the structure, which is encouraging cylindrical silo manufacturers to search for new types of shell construction. An innovative design of lightweight, industrial silos is a metal spiral-fold silo. The article describes the design of steel spiral-fold silos. The specifics of the spiral-fold silo design, which affects their stress-strain state, are analysed. The characteristics of the silo that was used as a source of samples for the experiment are given. The samples and equipment for the experimental study of a wall of a metal spiral-fold silo are considered. The stages of the experiment are described. The loading of the samples was performed by a central bending load applied in a static mode in the range from 0 kN to 5.5 kN. To determine the relative strains, the structure was unloaded after each loading stage. The analysis of the sample's relative strains which were measured by AVD-4 is made. The character of interaction and deformation of the wall with the folding lock is revealed. The degree of the folding lock opening was estimated. The character of work of the wall and the folding lock in the limit and non-limit states is obtained. A comparison of experimental results with finite element analysis in the LIRA-SAPR software package was performed. The conclusion about the reliable operation of the wall of a spiral-fold silo under operational and increased loads is substantiated
{"title":"EXPERIMENTAL STUDY OF WALL STRESS-STRAIN STATE OF A STEEL SPIRAL-FOLD SILOS","authors":"S. Pichugin, V. V. Shulhin, K.O. Oksenenko","doi":"10.31650/2707-3068-2023-27-94-103","DOIUrl":"https://doi.org/10.31650/2707-3068-2023-27-94-103","url":null,"abstract":"In the context of martial law, Ukraine's agricultural sector is suffering significant losses. By May 2022. Ukraine has already lost almost 13 million tonnes of elevator capacity, some of the grain warehouses have been completely destroyed, and some are in the occupied territories. In this regard, there is a need for elevator capacities, namely, prefabricated, cost-efficient storage capacities. Such structures are exemplified by silos. There are many design solutions for metal silos. However, the rising cost of materials is causing a need to reduce the material intensity of the structure, which is encouraging cylindrical silo manufacturers to search for new types of shell construction. An innovative design of lightweight, industrial silos is a metal spiral-fold silo. The article describes the design of steel spiral-fold silos. The specifics of the spiral-fold silo design, which affects their stress-strain state, are analysed. The characteristics of the silo that was used as a source of samples for the experiment are given. The samples and equipment for the experimental study of a wall of a metal spiral-fold silo are considered. The stages of the experiment are described. The loading of the samples was performed by a central bending load applied in a static mode in the range from 0 kN to 5.5 kN. To determine the relative strains, the structure was unloaded after each loading stage. The analysis of the sample's relative strains which were measured by AVD-4 is made. The character of interaction and deformation of the wall with the folding lock is revealed. The degree of the folding lock opening was estimated. The character of work of the wall and the folding lock in the limit and non-limit states is obtained. A comparison of experimental results with finite element analysis in the LIRA-SAPR software package was performed. The conclusion about the reliable operation of the wall of a spiral-fold silo under operational and increased loads is substantiated","PeriodicalId":365885,"journal":{"name":"Modern structures of metal and wood","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131129574","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 : 2023-07-01DOI: 10.31650/2707-3068-2023-27-52-58
O. Gibalenko, N. Chyzhenko, G.О. Melnik
Expansion of functional possibilities of the use of combined designs in the construction, improvement of architectural expressiveness of buildings and structures determine the need for improved requirements to ensure the quality and reliability of means and methods of corrosion protection. Currently, the development of computational methods to assess the reliability and structural safety associated with the construction of in-formation-analytical database key parameters of corrosion condition of metal construction. Methodology. This way creates the basis for setting and implementing management tasks operational life of buildings and structures in corrosive environments by improving the quality and reliability of primary and secondary protection of steel structures based on the level of corrosion hazard. Results. When using the principles of the process approach is the formulation and implementation of tasks of management of operational service life in corrosive environments. The principles of ensuring safety in terms of corrosion risk include the rationale for the sequence of steps to evaluate the survivability of building structures based on the principles of robust design, improvement and control measures the primary and secondary corrosion protection. Scientific novelty. The implementation of protection measures against corrosion according to the corrosion risk criterion helps to ensure the requirements of reliability of building structures in accordance with the design provisions of limit state method and to solve the problems of control of technological security for the rated life of construction projects. objects. Practical significance. The proposed generalized indicators of the actual structures’ corrosion state determine the structure’s operability as a whole. The functional dependencies between the operability of the main and auxiliary structures are established. The relationship between the values of corrosion resistance indicators and metal structures durability are determined. Actual technical condition control consists of checking that the values of these indicators are within acceptable limits. Taking into account the degree of operating environment aggressiveness is one of the determining factors in order to ensure the secondary protection effectiveness against corrosion. This procedure is the basis for the rational specifications appointment for anti-corrosion protection systems with subsequent display in the design and technological documentation
{"title":"THE DECREASE IN THE LEVEL OF CORROSION HAZARD IN THE RATIONAL DESIGN OF METAL STRUCTURES","authors":"O. Gibalenko, N. Chyzhenko, G.О. Melnik","doi":"10.31650/2707-3068-2023-27-52-58","DOIUrl":"https://doi.org/10.31650/2707-3068-2023-27-52-58","url":null,"abstract":"Expansion of functional possibilities of the use of combined designs in the construction, improvement of architectural expressiveness of buildings and structures determine the need for improved requirements to ensure the quality and reliability of means and methods of corrosion protection. Currently, the development of computational methods to assess the reliability and structural safety associated with the construction of in-formation-analytical database key parameters of corrosion condition of metal construction. Methodology. This way creates the basis for setting and implementing management tasks operational life of buildings and structures in corrosive environments by improving the quality and reliability of primary and secondary protection of steel structures based on the level of corrosion hazard. Results. When using the principles of the process approach is the formulation and implementation of tasks of management of operational service life in corrosive environments. The principles of ensuring safety in terms of corrosion risk include the rationale for the sequence of steps to evaluate the survivability of building structures based on the principles of robust design, improvement and control measures the primary and secondary corrosion protection. Scientific novelty. The implementation of protection measures against corrosion according to the corrosion risk criterion helps to ensure the requirements of reliability of building structures in accordance with the design provisions of limit state method and to solve the problems of control of technological security for the rated life of construction projects. objects. Practical significance. The proposed generalized indicators of the actual structures’ corrosion state determine the structure’s operability as a whole. The functional dependencies between the operability of the main and auxiliary structures are established. The relationship between the values of corrosion resistance indicators and metal structures durability are determined. Actual technical condition control consists of checking that the values of these indicators are within acceptable limits. Taking into account the degree of operating environment aggressiveness is one of the determining factors in order to ensure the secondary protection effectiveness against corrosion. This procedure is the basis for the rational specifications appointment for anti-corrosion protection systems with subsequent display in the design and technological documentation","PeriodicalId":365885,"journal":{"name":"Modern structures of metal and wood","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124532718","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 : 2023-07-01DOI: 10.31650/2707-3068-2023-27-13-18
A. Gilodo, A.M. Arsiriy, Yuliia Somina, I.S. Oliynyk
To study the stress-strain state of the mesh dome model with the diameter 4 m, the series of glulam rods were prepared for the central compression test. The tests were carried out in the laboratory of the Department of Metal, Wooden and Plastic Structures. The stresses at the distinguished points of the elements were determined through the deformations using the resistance strain sensors. The feature of prismatic samples was the presence of stress concentrators in the support zones in the form of the holes for the location of universal connectors [3]. The significant sizes of the model made it possible to minimize the influence of the scaling factor on the obtained results. The general conclusion of the study should be considered high bearing capacity of the tested samples. The destruction of the samples took place in the support zone due to the crushing of the wood. The next tasks of the research will be the optimization of the elements sizes and testing of the dome model. The cross-section of the elements, in addition to providing the load-bearing capacity, is affected by the need to obtain certain thermotechnical characteristics of the enclosure, i.e. the elements of the dome must have the dimensions that allow placing a layer of effective insulation in their plane. A separate task is the selection of the roof, which can be considered exclusively as a part of the permanent load on the supporting system, or as a continuous shell that unfastens the frame
{"title":"EXPERIMENTAL ANALYSIS OF MESH ELEMENTS GLULAM DOME","authors":"A. Gilodo, A.M. Arsiriy, Yuliia Somina, I.S. Oliynyk","doi":"10.31650/2707-3068-2023-27-13-18","DOIUrl":"https://doi.org/10.31650/2707-3068-2023-27-13-18","url":null,"abstract":"To study the stress-strain state of the mesh dome model with the diameter 4 m, the series of glulam rods were prepared for the central compression test. The tests were carried out in the laboratory of the Department of Metal, Wooden and Plastic Structures. The stresses at the distinguished points of the elements were determined through the deformations using the resistance strain sensors. The feature of prismatic samples was the presence of stress concentrators in the support zones in the form of the holes for the location of universal connectors [3]. The significant sizes of the model made it possible to minimize the influence of the scaling factor on the obtained results. The general conclusion of the study should be considered high bearing capacity of the tested samples. The destruction of the samples took place in the support zone due to the crushing of the wood. The next tasks of the research will be the optimization of the elements sizes and testing of the dome model. The cross-section of the elements, in addition to providing the load-bearing capacity, is affected by the need to obtain certain thermotechnical characteristics of the enclosure, i.e. the elements of the dome must have the dimensions that allow placing a layer of effective insulation in their plane. A separate task is the selection of the roof, which can be considered exclusively as a part of the permanent load on the supporting system, or as a continuous shell that unfastens the frame","PeriodicalId":365885,"journal":{"name":"Modern structures of metal and wood","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130659334","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 : 2023-07-01DOI: 10.31650/2707-3068-2023-27-67-74
S. Gomon, S. Homon, A. Pavluk, Y.V. Puhash
The most common use of wood in construction is for bending elements. The calculation of bending members made of glued laminated timber requires the use of the section modulus of this member and the calculated values of the bending strength of the timber. The design bending strength of wood is determined based on the characteristic values obtained from the laws of elastic material under load. However, this statement completely contradicts the anisotropy of wood in its tensile and compressive behavior. If it is known that wood works 90-95% to failure in longitudinal tension, it is then it can be assumed that it is elastic at all. However, in longitudinal deformation, there is non-linear behavior with increasing elastic and plastic strains. Furthermore, the longitudinal tensile strength of wood is almost twice that of longitudinal compression. Therefore, even if the relative deformations in the wood are the same different compressive and tensile stresses arise in the bending element, i.e. . Many authors who have carried out experimental and theoretical studies on the performance of timber beams have pointed out that the neutral force line in the cross-section of the element in direct transverse bending, with increasing levels of single load, shifts towards the tensile zone. Therefore, using the moment of resistance of the cross section in the wooden element to determine the section modulus is incorrect. The moment of resistance of a section of a timber member is only determined if the centre of gravity of the section coincides with the centre of force line. Usually, the failure of long wooden beams ( ) in transverse bending usually occurs due to the fracture of the most stressed outer layers of wood in the of the tensile area and is brittle in nature. It is on such elements that the the temporary bending strength. It is on such elements that the bending strength is crucial. However, the values of , usually determined in the outermost wood layers of the tensile zone, based on the condition, only reach values of 70-75% of the longitudinal tensile strength of wood . It is not possible to determine the tensile strength of wood at this stress level. Therefore, the results of determining the bending strength of wood using the moment of resistance of the cross-section of a timber element determined in the limiting condition are erroneous due to the impossibility of establishing values
{"title":"REGARDING THE IMPROVEMENT OF CURRENT NORMATIVE DOCUMENTS FOR THE CALCULATION OF BENDING WOODEN ELEMENTS AND STRUCTURES","authors":"S. Gomon, S. Homon, A. Pavluk, Y.V. Puhash","doi":"10.31650/2707-3068-2023-27-67-74","DOIUrl":"https://doi.org/10.31650/2707-3068-2023-27-67-74","url":null,"abstract":"The most common use of wood in construction is for bending elements. The calculation of bending members made of glued laminated timber requires the use of the section modulus of this member and the calculated values of the bending strength of the timber. The design bending strength of wood is determined based on the characteristic values obtained from the laws of elastic material under load. However, this statement completely contradicts the anisotropy of wood in its tensile and compressive behavior. If it is known that wood works 90-95% to failure in longitudinal tension, it is then it can be assumed that it is elastic at all. However, in longitudinal deformation, there is non-linear behavior with increasing elastic and plastic strains. Furthermore, the longitudinal tensile strength of wood is almost twice that of longitudinal compression. Therefore, even if the relative deformations in the wood are the same different compressive and tensile stresses arise in the bending element, i.e. . Many authors who have carried out experimental and theoretical studies on the performance of timber beams have pointed out that the neutral force line in the cross-section of the element in direct transverse bending, with increasing levels of single load, shifts towards the tensile zone. Therefore, using the moment of resistance of the cross section in the wooden element to determine the section modulus is incorrect. The moment of resistance of a section of a timber member is only determined if the centre of gravity of the section coincides with the centre of force line. Usually, the failure of long wooden beams ( ) in transverse bending usually occurs due to the fracture of the most stressed outer layers of wood in the of the tensile area and is brittle in nature. It is on such elements that the the temporary bending strength. It is on such elements that the bending strength is crucial. However, the values of , usually determined in the outermost wood layers of the tensile zone, based on the condition, only reach values of 70-75% of the longitudinal tensile strength of wood . It is not possible to determine the tensile strength of wood at this stress level. Therefore, the results of determining the bending strength of wood using the moment of resistance of the cross-section of a timber element determined in the limiting condition are erroneous due to the impossibility of establishing values","PeriodicalId":365885,"journal":{"name":"Modern structures of metal and wood","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124092940","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 : 2023-07-01DOI: 10.31650/2707-3068-2023-27-5-12
A. Gilodo, A.M. Arsiriy
Strengthening methods of reinforced concrete roofs are known and developed in sufficient detail. They are classified according to the constructions: strengthening of simply supported and continuous beams, cantilever beams, panels, girders, trusses, arches, etc. But all the proposed ways have common disadvantages – they require open space for work, provide for preliminary unloading, and under certain circumstances, partial dismantling of significantly damaged structures, and cannot consider the features of a specific technical situation naturally. We offer the strengthening method of not a single beam, but the entire roof block, with limited time period and the need to restart the production process in the shortest possible time, which has got critical damage, during the situation that excludes temporary unloading, and the dismantling of damaged areas or structures is impossible. The additional technical problem is that the supporting vertical structures of the emergency shutdown – the columns are also in a critical technical condition. Therefore, the attempt to dismantle any load-bearing element will lead to the complete destruction of a large part of the industrial building and the cessation of production for a considerable time period. The use of a spatial steel frame simplifies the strengthening work, speeds up the return to production and does not increase the material costs
{"title":"STRENGTHENING OF REINFORCED CONCRETE ROOF WITH STEEL FRAME","authors":"A. Gilodo, A.M. Arsiriy","doi":"10.31650/2707-3068-2023-27-5-12","DOIUrl":"https://doi.org/10.31650/2707-3068-2023-27-5-12","url":null,"abstract":"Strengthening methods of reinforced concrete roofs are known and developed in sufficient detail. They are classified according to the constructions: strengthening of simply supported and continuous beams, cantilever beams, panels, girders, trusses, arches, etc. But all the proposed ways have common disadvantages – they require open space for work, provide for preliminary unloading, and under certain circumstances, partial dismantling of significantly damaged structures, and cannot consider the features of a specific technical situation naturally. We offer the strengthening method of not a single beam, but the entire roof block, with limited time period and the need to restart the production process in the shortest possible time, which has got critical damage, during the situation that excludes temporary unloading, and the dismantling of damaged areas or structures is impossible. The additional technical problem is that the supporting vertical structures of the emergency shutdown – the columns are also in a critical technical condition. Therefore, the attempt to dismantle any load-bearing element will lead to the complete destruction of a large part of the industrial building and the cessation of production for a considerable time period. The use of a spatial steel frame simplifies the strengthening work, speeds up the return to production and does not increase the material costs","PeriodicalId":365885,"journal":{"name":"Modern structures of metal and wood","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131422171","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 : 2023-07-01DOI: 10.31650/2707-3068-2023-27-84-93
E. Klimenko, A. Popadenko, S. Kolesnichenko
The article presents the results of a study of the features of the use of thermographic flaw detection for steel building structures, taking into account their actual state under operating conditions. Since these structures are subjected to significant loads, they are subject to failure, including cracking, corrosion, rupture, and other damage. Compliance with the safe operation of steel structures is essential to ensure the safety of personnel and the normal production process. Compliance with safety rules should be regular and systematic, including periodic inspections and diagnosing the condition of steel structures. Thermographic flaw detection methods consists in measuring the surface temperature of a structure using infrared cameras and detecting temperature anomalies that may indicate the presence of defects. The objective of the study is to increase the efficiency of using the active thermography method for examining operated steel structures. Identify possible difficulties that will arise in the application of this method, and develop recommendations to overcome the identified problems. The most significant aspect that can affect the quality of thermographic flaw detection is a characteristic of infrared emission of the investigated structure’s part. The low value of this indicator leads to an increase in the amount of false data, which in turn reduces the reliability of the obtained results. Another equally important part of the work of an engineer in thermographic flaw detection is the choice of the method and place of heating the structure, which depends on specific cases and inspection tasks. Eventually, active thermography may be useful and effective method for flaw detection of steel building structures. However, its application must be carried out in the context of all factors that may affect the accuracy and efficiency of the equipment concerned
{"title":"PECULIARITIES OF THE APPLICATION OF THERMOGRAPHIC DEFECTOSCOPY FOR STEEL BUILDING STRUCTURES TAKING INTO ACCOUNT THEIR REAL STATE UNDER OPERATION CONDITIONS","authors":"E. Klimenko, A. Popadenko, S. Kolesnichenko","doi":"10.31650/2707-3068-2023-27-84-93","DOIUrl":"https://doi.org/10.31650/2707-3068-2023-27-84-93","url":null,"abstract":"The article presents the results of a study of the features of the use of thermographic flaw detection for steel building structures, taking into account their actual state under operating conditions. Since these structures are subjected to significant loads, they are subject to failure, including cracking, corrosion, rupture, and other damage. Compliance with the safe operation of steel structures is essential to ensure the safety of personnel and the normal production process. Compliance with safety rules should be regular and systematic, including periodic inspections and diagnosing the condition of steel structures. Thermographic flaw detection methods consists in measuring the surface temperature of a structure using infrared cameras and detecting temperature anomalies that may indicate the presence of defects. The objective of the study is to increase the efficiency of using the active thermography method for examining operated steel structures. Identify possible difficulties that will arise in the application of this method, and develop recommendations to overcome the identified problems. The most significant aspect that can affect the quality of thermographic flaw detection is a characteristic of infrared emission of the investigated structure’s part. The low value of this indicator leads to an increase in the amount of false data, which in turn reduces the reliability of the obtained results. Another equally important part of the work of an engineer in thermographic flaw detection is the choice of the method and place of heating the structure, which depends on specific cases and inspection tasks. Eventually, active thermography may be useful and effective method for flaw detection of steel building structures. However, its application must be carried out in the context of all factors that may affect the accuracy and efficiency of the equipment concerned","PeriodicalId":365885,"journal":{"name":"Modern structures of metal and wood","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129550621","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 : 2023-07-01DOI: 10.31650/2707-3068-2023-27-35-40
Yuliia Somina, I. Karpiuk, D. Antonova
In the article are presented the main results of experimental studies of deformability of the reinforcement of common damaged and brought, in the course of the previous tests, to the critical state by the 1st group r.c. beams reinforced with carbon fibre (CFRP) sheet in the lower tensioned zone and on the support area. Namely, according to the results of the experiment, using the COMPEX program, adequate mathematical models of the deformations of steel reinforcement of CFRP-strengthened reinforced concrete specimens-beams under the action of low-cycle sign-constant loading were derived, that reflect the influence of these factors both individually and in interaction with each other. Analyzing these models, the features of the development of tensile reinforcement in the specified conditions, were established. In particular, the factors that have the greatest influence on deformations are the relative shear span and the level of low-cycle loading. As compared with the series of tests of ordinary r.c. samples, presence of the external CFRP strengthening reduced deformation of the tensioned steel reinforcement by 1.65 times on the average. There occurs a re-distribution of the tension forces between them
{"title":"DEFORMABILITY OF STEEL REINFORCEMENT OF DAMAGED CFRP-STRENGTHENED BEAMS UNDER THE ACTION OF CYCLIC LOADING","authors":"Yuliia Somina, I. Karpiuk, D. Antonova","doi":"10.31650/2707-3068-2023-27-35-40","DOIUrl":"https://doi.org/10.31650/2707-3068-2023-27-35-40","url":null,"abstract":"In the article are presented the main results of experimental studies of deformability of the reinforcement of common damaged and brought, in the course of the previous tests, to the critical state by the 1st group r.c. beams reinforced with carbon fibre (CFRP) sheet in the lower tensioned zone and on the support area. Namely, according to the results of the experiment, using the COMPEX program, adequate mathematical models of the deformations of steel reinforcement of CFRP-strengthened reinforced concrete specimens-beams under the action of low-cycle sign-constant loading were derived, that reflect the influence of these factors both individually and in interaction with each other. Analyzing these models, the features of the development of tensile reinforcement in the specified conditions, were established. In particular, the factors that have the greatest influence on deformations are the relative shear span and the level of low-cycle loading. As compared with the series of tests of ordinary r.c. samples, presence of the external CFRP strengthening reduced deformation of the tensioned steel reinforcement by 1.65 times on the average. There occurs a re-distribution of the tension forces between them","PeriodicalId":365885,"journal":{"name":"Modern structures of metal and wood","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132598689","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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