Abstract In the present paper, the acoustic emission (AE) device is used with an innovative approach, based on the calculation of P-wave propagation velocity (vp), to detect the stiffness characteristics and the diffused damage of in-service old concrete structures. The paper presents the result of a recent testing campaign carried out on the slant pillars composing the vertical bearing structures designed by Pier Luigi Nervi in one of his most iconic buildings: the Hall B of Torino Esposizioni. In order to investigate the properties of these inclined pillars, localizations of artificial sources (hammer impacts), by the triangulation procedure, were performed on three different inclined elements characterized by stiffness discrepancies due to different causes: the casting procedures, executed in different stages, and the enlargement of the hall happened a few years later the beginning of the construction. In the present work, the relationship between the velocity of AE signals and the elastic characteristics (principally elastic modulus, E) is evaluated in order to discriminate the stiffness level of the slanted pillars. The procedure presented made it possible to develop an innovative investigation method able to estimate, by means of AE, the state of conservation and the elastic properties and the damage level of the monitored concrete and reinforced concrete structures.
摘要本文采用一种基于纵波传播速度(vp)计算的声发射(AE)装置来检测在役老旧混凝土结构的刚度特征和扩散损伤。本文介绍了最近对Pier Luigi Nervi在其最具代表性的建筑之一:都灵Esposizioni大厅B中设计的垂直承重结构的斜柱进行测试的结果。为了研究这些倾斜柱子的特性，通过三角测量程序，对三个不同的倾斜元素进行了人工源(锤击)的定位，这些元素由于不同的原因而具有刚度差异:浇铸过程，在不同阶段执行，大厅的扩建发生在施工开始的几年后。在本工作中，为了区分斜柱的刚度水平，评估了声发射信号的速度与弹性特性(主要是弹性模量，E)之间的关系。所提出的程序使开发一种创新的调查方法成为可能，该方法能够通过声发射来估计受监测的混凝土和钢筋混凝土结构的保存状态、弹性特性和损伤水平。
{"title":"AE propagation velocity calculation for stiffness estimation in Pier Luigi Nervi’s concrete structures","authors":"E. Lenticchia, A. Bertetto, R. Ceravolo","doi":"10.1515/cls-2021-0010","DOIUrl":"https://doi.org/10.1515/cls-2021-0010","url":null,"abstract":"Abstract In the present paper, the acoustic emission (AE) device is used with an innovative approach, based on the calculation of P-wave propagation velocity (vp), to detect the stiffness characteristics and the diffused damage of in-service old concrete structures. The paper presents the result of a recent testing campaign carried out on the slant pillars composing the vertical bearing structures designed by Pier Luigi Nervi in one of his most iconic buildings: the Hall B of Torino Esposizioni. In order to investigate the properties of these inclined pillars, localizations of artificial sources (hammer impacts), by the triangulation procedure, were performed on three different inclined elements characterized by stiffness discrepancies due to different causes: the casting procedures, executed in different stages, and the enlargement of the hall happened a few years later the beginning of the construction. In the present work, the relationship between the velocity of AE signals and the elastic characteristics (principally elastic modulus, E) is evaluated in order to discriminate the stiffness level of the slanted pillars. The procedure presented made it possible to develop an innovative investigation method able to estimate, by means of AE, the state of conservation and the elastic properties and the damage level of the monitored concrete and reinforced concrete structures.","PeriodicalId":44435,"journal":{"name":"Curved and Layered Structures","volume":"8 1","pages":"109 - 118"},"PeriodicalIF":1.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/cls-2021-0010","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44712923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Ary, Yuwana Sanjaya, A. Prabowo, F. Imaduddin, N. Nordin, Iwan Istanto, J. Cho
Abstract Shell Eco-Marathon (SEM) is an international competition among university students that involves designing, building, and driving energy-efficient cars. The car frame is the most crucial aspect influencing the strength of the car. This research aims to obtain maximum torsional strength with variations in the material and thickness of the frame. Calculation and testing are done using the simulation method to obtain a strong car frame. This simulation method is calculated by a series of finite element analyses. Then, data from the simulation method are obtained in the form of deformation and safety factors. By comparing the moment received with its deformation, torsional stiffness is then obtained. Furthermore, the torsional stiffness is divided by the weight to produce a value ratio. It is known that the factor which has the most significant influence on the difference in torsional stiffness of each variation is the shear modulus of the material used. In contrast, the weight of the chassis is influenced by the density of the material and the thickness of the chassis. Additionally, the safety factor of each variation is strongly influenced by the strength of the chassis structure itself. The results of this study will demonstrate the car frame design with the best performance.
{"title":"Numerical estimation of the torsional stiffness characteristics on urban Shell Eco-Marathon (SEM) vehicle design","authors":"A. Ary, Yuwana Sanjaya, A. Prabowo, F. Imaduddin, N. Nordin, Iwan Istanto, J. Cho","doi":"10.1515/cls-2021-0016","DOIUrl":"https://doi.org/10.1515/cls-2021-0016","url":null,"abstract":"Abstract Shell Eco-Marathon (SEM) is an international competition among university students that involves designing, building, and driving energy-efficient cars. The car frame is the most crucial aspect influencing the strength of the car. This research aims to obtain maximum torsional strength with variations in the material and thickness of the frame. Calculation and testing are done using the simulation method to obtain a strong car frame. This simulation method is calculated by a series of finite element analyses. Then, data from the simulation method are obtained in the form of deformation and safety factors. By comparing the moment received with its deformation, torsional stiffness is then obtained. Furthermore, the torsional stiffness is divided by the weight to produce a value ratio. It is known that the factor which has the most significant influence on the difference in torsional stiffness of each variation is the shear modulus of the material used. In contrast, the weight of the chassis is influenced by the density of the material and the thickness of the chassis. Additionally, the safety factor of each variation is strongly influenced by the strength of the chassis structure itself. The results of this study will demonstrate the car frame design with the best performance.","PeriodicalId":44435,"journal":{"name":"Curved and Layered Structures","volume":"8 1","pages":"167 - 180"},"PeriodicalIF":1.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/cls-2021-0016","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43337127","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}
D. Abruzzese, Davide Bracale, Damiano Forconi, Gianmarco Grizzi, A. Micheletti, Daniele Paradisi, A. Tiero, Sreymom Vuth
Abstract Recently, structural monitoring technology invested in methodologies that give direct information on structures’ stress state. Optic fibers, strain gauges, pressure cells give real-time data on the stress condition of a structural element, often determining the area where peak stresses have been reached, with a clear advantage over other less direct monitoring methodologies, such as, e.g., the use of accelerometers and inverse analysis to estimate internal forces. In addition, stresses can be recorded in a data log for analysis after a loading event, as well as for taking into account the lifelong stress state of the structure. Beams and columns of a reinforced concrete frame can be effectively monitored for flexural loads. Differently, thin shells are most of their lifespan under membrane regime, and, when properly designed, they rarely move to the bending regime. Our proposal is to monitor the stress in thin structures by small-sized low-cost devices able to record the stress history at key locations, sending alerts when necessary, with the aim of ensuring safety against the risk of collapse, or simply to perform maintenance/repairing activities. Such devices are realized with cheap off-the-shelf electronics and traditional strain gauges. The application examples are given as laboratory tests performed on a reinforced concrete plate, a masonry panel, and a steel beam. Results shows that the permanent monitoring control of stresses can be conveniently carried out on new structures using low-cost devices of the type we designed and realized in-house.
{"title":"Permanent monitoring of thin structures with low-cost devices","authors":"D. Abruzzese, Davide Bracale, Damiano Forconi, Gianmarco Grizzi, A. Micheletti, Daniele Paradisi, A. Tiero, Sreymom Vuth","doi":"10.1515/cls-2021-0018","DOIUrl":"https://doi.org/10.1515/cls-2021-0018","url":null,"abstract":"Abstract Recently, structural monitoring technology invested in methodologies that give direct information on structures’ stress state. Optic fibers, strain gauges, pressure cells give real-time data on the stress condition of a structural element, often determining the area where peak stresses have been reached, with a clear advantage over other less direct monitoring methodologies, such as, e.g., the use of accelerometers and inverse analysis to estimate internal forces. In addition, stresses can be recorded in a data log for analysis after a loading event, as well as for taking into account the lifelong stress state of the structure. Beams and columns of a reinforced concrete frame can be effectively monitored for flexural loads. Differently, thin shells are most of their lifespan under membrane regime, and, when properly designed, they rarely move to the bending regime. Our proposal is to monitor the stress in thin structures by small-sized low-cost devices able to record the stress history at key locations, sending alerts when necessary, with the aim of ensuring safety against the risk of collapse, or simply to perform maintenance/repairing activities. Such devices are realized with cheap off-the-shelf electronics and traditional strain gauges. The application examples are given as laboratory tests performed on a reinforced concrete plate, a masonry panel, and a steel beam. Results shows that the permanent monitoring control of stresses can be conveniently carried out on new structures using low-cost devices of the type we designed and realized in-house.","PeriodicalId":44435,"journal":{"name":"Curved and Layered Structures","volume":"8 1","pages":"188 - 195"},"PeriodicalIF":1.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/cls-2021-0018","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42275525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract At the time of completion in 1961, the roof of St. Charles Church became the largest unbalanced hyperbolic paraboloid structure in the United States and the only shell structure in Spokane, WA. Situated on an 8-acre site on the north side of the city, St. Charles is a modernist structure designed through partnership of Funk, Molander & Johnson engineers, architect William C. James and in consultation with Professor T.Y. Lin of the Structural Engineering Laboratory at the University of California, Berkeley. This asymmetric structure spans over 33.5 m (110 ft) and utilizes folded edge beams that taper from 1067 mm (42 in) at the base to a 76.2 mm (3 in) thickness at the topmost edge using regular strength reinforcing steel and concrete load carrying components. The novelty of the pre-stressed shell structure serves both architectural and structural design criteria by delivering a large, uninterrupted interior sanctuary space in materially and economically efficient manner. This structural assessment summarizes the roof’s historic design and construction according to the original construction documents, newspaper reports and historic photographs. The FEA is completed using UBC 1955 design loads and ACI 334 Concrete Shell Structures provisions.
{"title":"Structural assessment of St. Charles hyperbolic paraboloid roof","authors":"J. Schultz, Viktoria Henriksson","doi":"10.1515/cls-2021-0015","DOIUrl":"https://doi.org/10.1515/cls-2021-0015","url":null,"abstract":"Abstract At the time of completion in 1961, the roof of St. Charles Church became the largest unbalanced hyperbolic paraboloid structure in the United States and the only shell structure in Spokane, WA. Situated on an 8-acre site on the north side of the city, St. Charles is a modernist structure designed through partnership of Funk, Molander & Johnson engineers, architect William C. James and in consultation with Professor T.Y. Lin of the Structural Engineering Laboratory at the University of California, Berkeley. This asymmetric structure spans over 33.5 m (110 ft) and utilizes folded edge beams that taper from 1067 mm (42 in) at the base to a 76.2 mm (3 in) thickness at the topmost edge using regular strength reinforcing steel and concrete load carrying components. The novelty of the pre-stressed shell structure serves both architectural and structural design criteria by delivering a large, uninterrupted interior sanctuary space in materially and economically efficient manner. This structural assessment summarizes the roof’s historic design and construction according to the original construction documents, newspaper reports and historic photographs. The FEA is completed using UBC 1955 design loads and ACI 334 Concrete Shell Structures provisions.","PeriodicalId":44435,"journal":{"name":"Curved and Layered Structures","volume":"8 1","pages":"157 - 166"},"PeriodicalIF":1.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/cls-2021-0015","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44212951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The form-finding analysis is a crucial step for determining the stable self-equilibrated states for tensegrity structures, in the absence of external loads. This form-finding problem leads to the evaluation of both the self-stress in the elements and the shape of the tensegrity structure. This paper presents a novel method for determining feasible integral self-stress states for tensegrity structures, that is self-equilibrated states consistent with the unilateral behaviour of the elements, struts in compression and cables in tension, and with the symmetry properties of the structure. In particular, once defined the connectivity between the elements and the nodal coordinates, the feasible self-stress states are determined by suitably investigating the Distributed Static Indeterminacy (DSI). The proposed method allows for obtaining feasible integral self-stress solutions by a unique Singular Value Decomposition (SVD) of the equilibrium matrix, whereas other approaches in the literature require two SVD. Moreover, the proposed approach allows for effectively determining the Force Denstiy matrix, whose properties are strictly related to the super-stability of the tensegrity structures. Three tensegrity structures were studied in order to assess and discuss the efficiency and accuracy of the proposed innovative method.
{"title":"A novel method for determining the feasible integral self-stress states for tensegrity structures","authors":"A. Fraddosio, Gaetano Pavone, M. Piccioni","doi":"10.1515/cls-2021-0007","DOIUrl":"https://doi.org/10.1515/cls-2021-0007","url":null,"abstract":"Abstract The form-finding analysis is a crucial step for determining the stable self-equilibrated states for tensegrity structures, in the absence of external loads. This form-finding problem leads to the evaluation of both the self-stress in the elements and the shape of the tensegrity structure. This paper presents a novel method for determining feasible integral self-stress states for tensegrity structures, that is self-equilibrated states consistent with the unilateral behaviour of the elements, struts in compression and cables in tension, and with the symmetry properties of the structure. In particular, once defined the connectivity between the elements and the nodal coordinates, the feasible self-stress states are determined by suitably investigating the Distributed Static Indeterminacy (DSI). The proposed method allows for obtaining feasible integral self-stress solutions by a unique Singular Value Decomposition (SVD) of the equilibrium matrix, whereas other approaches in the literature require two SVD. Moreover, the proposed approach allows for effectively determining the Force Denstiy matrix, whose properties are strictly related to the super-stability of the tensegrity structures. Three tensegrity structures were studied in order to assess and discuss the efficiency and accuracy of the proposed innovative method.","PeriodicalId":44435,"journal":{"name":"Curved and Layered Structures","volume":"8 1","pages":"70 - 88"},"PeriodicalIF":1.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/cls-2021-0007","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43745112","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}
B. W. Lenggana, A. Prabowo, U. Ubaidillah, F. Imaduddin, E. Surojo, H. Nubli, R. Adiputra
Abstract A research subject in structural engineering is the problem of vibration under a loading object. The two-dimensional (2D) model of a structure under loading is an example. In general, this case uses an object that is given a random frequency, which then causes various changes in shape depending on the frequency model. To determine the difference in performance by looking at the different forms of each mode, modal analysis with ANSYS was used. The samples to be simulated were metal plates with three variations of the model, namely, a virgin metal plate without any holes or stiffness, plates with given holes, and metal plates with stiffness on one side. The model was simulated with modal analysis, so that 20 natural frequencies were recorded. The sample also used different materials: low-carbon steel materials (AISI 304), marine materials (AISI 1090), and ice-class materials (AR 235). Several random-frequency models proved the deformation of different objects. Variations of sheet-metal designs were applied, such as pure sheet metal, giving holes to the sides, and stiffening the simulated metal sheet.
{"title":"Effects of mechanical vibration on designed steel-based plate geometries: behavioral estimation subjected to applied material classes using finite-element method","authors":"B. W. Lenggana, A. Prabowo, U. Ubaidillah, F. Imaduddin, E. Surojo, H. Nubli, R. Adiputra","doi":"10.1515/cls-2021-0021","DOIUrl":"https://doi.org/10.1515/cls-2021-0021","url":null,"abstract":"Abstract A research subject in structural engineering is the problem of vibration under a loading object. The two-dimensional (2D) model of a structure under loading is an example. In general, this case uses an object that is given a random frequency, which then causes various changes in shape depending on the frequency model. To determine the difference in performance by looking at the different forms of each mode, modal analysis with ANSYS was used. The samples to be simulated were metal plates with three variations of the model, namely, a virgin metal plate without any holes or stiffness, plates with given holes, and metal plates with stiffness on one side. The model was simulated with modal analysis, so that 20 natural frequencies were recorded. The sample also used different materials: low-carbon steel materials (AISI 304), marine materials (AISI 1090), and ice-class materials (AR 235). Several random-frequency models proved the deformation of different objects. Variations of sheet-metal designs were applied, such as pure sheet metal, giving holes to the sides, and stiffening the simulated metal sheet.","PeriodicalId":44435,"journal":{"name":"Curved and Layered Structures","volume":"8 1","pages":"225 - 240"},"PeriodicalIF":1.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/cls-2021-0021","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43037518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract An historical overview is presented concerning the theory of shell structures and thin domes. Early conjectures proposed, among others, by French, German, and Russian Authors are discussed. Static and kinematic matrix operator equations are formulated explicitly in the case of shells of revolution and thin domes. It is realized how the static and kinematic matrix operators are one the ad-joint of the other, and, on the other hand, it can be rigorously demonstrated through the definition of stiffness matrix and the application of virtual work principle. In this context, any possible omission present in the previous approaches becomes evident. As regards thin shells of revolution (thin domes), the elastic problem results to be internally statically-determinate, in analogy to the case of curved beams, being characterized by a system of two equilibrium equations in two unknowns. Thus, the elastic solution can be obtained just based on the equilibrium equations and independently of the shape of the membrane itself. The same cannot be affirmed for the unidimensional elements without ‚exural stiffness (ropes). Generally speaking, the static problem of elastic domes is governed by two parameters, the constraint reactions being assumed to be tangential to meridians at the dome edges: the shallowness ratio and the thickness of the dome. On the other hand, when the dome thickness tends to zero, the funicularity emerges and prevails, independently of the shallowness ratio or the shape of the dome. When the thickness is finite, an optimal shape is demonstrated to exist, which minimizes the flexural regime if compared to the membrane one.
{"title":"Funicularity in elastic domes: Coupled effects of shape and thickness","authors":"F. Accornero, A. Carpinteri","doi":"10.1515/cls-2021-0017","DOIUrl":"https://doi.org/10.1515/cls-2021-0017","url":null,"abstract":"Abstract An historical overview is presented concerning the theory of shell structures and thin domes. Early conjectures proposed, among others, by French, German, and Russian Authors are discussed. Static and kinematic matrix operator equations are formulated explicitly in the case of shells of revolution and thin domes. It is realized how the static and kinematic matrix operators are one the ad-joint of the other, and, on the other hand, it can be rigorously demonstrated through the definition of stiffness matrix and the application of virtual work principle. In this context, any possible omission present in the previous approaches becomes evident. As regards thin shells of revolution (thin domes), the elastic problem results to be internally statically-determinate, in analogy to the case of curved beams, being characterized by a system of two equilibrium equations in two unknowns. Thus, the elastic solution can be obtained just based on the equilibrium equations and independently of the shape of the membrane itself. The same cannot be affirmed for the unidimensional elements without ‚exural stiffness (ropes). Generally speaking, the static problem of elastic domes is governed by two parameters, the constraint reactions being assumed to be tangential to meridians at the dome edges: the shallowness ratio and the thickness of the dome. On the other hand, when the dome thickness tends to zero, the funicularity emerges and prevails, independently of the shallowness ratio or the shape of the dome. When the thickness is finite, an optimal shape is demonstrated to exist, which minimizes the flexural regime if compared to the membrane one.","PeriodicalId":44435,"journal":{"name":"Curved and Layered Structures","volume":"8 1","pages":"181 - 187"},"PeriodicalIF":1.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/cls-2021-0017","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49082361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract According to Heyman’s safe theorem of the limit analysis of masonry structures, the safety of masonry arches can be verified by finding at least one line of thrust entirely laying within the masonry and in equilibrium with external loads. If such a solution does exist, two extreme configurations of the thrust line can be determined, respectively referred to as solutions of minimum and maximum thrust. In this paper it is presented a numerical procedure for determining both these solutions with reference to masonry arches of general shape, subjected to both vertical and horizontal loads. The algorithm takes advantage of a simplification of the equations underlying the Thrust Network Analysis. Actually, for the case of planar lines of thrust, the horizontal components of the reference thrusts can be computed in closed form at each iteration and for any arbitrary loading condition. The heights of the points of the thrust line are then computed by solving a constrained linear optimization problem by means of the Dual-Simplex algorithm. The MATLAB implementation of presented algorithm is described in detail and made freely available to interested users (https://bit.ly/3krlVxH). Two numerical examples regarding a pointed and a lowered circular arch are presented in order to show the performance of the method.
{"title":"ArchLab: a MATLAB tool for the Thrust Line Analysis of masonry arches","authors":"F. Marmo","doi":"10.1515/cls-2021-0003","DOIUrl":"https://doi.org/10.1515/cls-2021-0003","url":null,"abstract":"Abstract According to Heyman’s safe theorem of the limit analysis of masonry structures, the safety of masonry arches can be verified by finding at least one line of thrust entirely laying within the masonry and in equilibrium with external loads. If such a solution does exist, two extreme configurations of the thrust line can be determined, respectively referred to as solutions of minimum and maximum thrust. In this paper it is presented a numerical procedure for determining both these solutions with reference to masonry arches of general shape, subjected to both vertical and horizontal loads. The algorithm takes advantage of a simplification of the equations underlying the Thrust Network Analysis. Actually, for the case of planar lines of thrust, the horizontal components of the reference thrusts can be computed in closed form at each iteration and for any arbitrary loading condition. The heights of the points of the thrust line are then computed by solving a constrained linear optimization problem by means of the Dual-Simplex algorithm. The MATLAB implementation of presented algorithm is described in detail and made freely available to interested users (https://bit.ly/3krlVxH). Two numerical examples regarding a pointed and a lowered circular arch are presented in order to show the performance of the method.","PeriodicalId":44435,"journal":{"name":"Curved and Layered Structures","volume":"8 1","pages":"26 - 35"},"PeriodicalIF":1.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/cls-2021-0003","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45721131","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}
O. Mareeva, V. Ermilov, V. Snezhko, D. Benin, A. Bakshtanin
Abstract This paper is an experimental study of the quasi-static mechanical compressive properties of the reinforced closed-cell aluminum alloy foams with different cell orientations at different strain rates. The reinforced foam samples were obtained via the powder metallurgical route. The results of the compression tests revealed that the deformation behavior and mechanical properties of foamed aluminum composites are highly dependent on the orientation of the reinforcing mesh. Differences in the deformation behavior of foams appear to be influenced by the mechanical properties of the matrix material, by foam deformation mechanisms, and by the mechanical properties of the reinforcement. The yield stress, plateau stress, densification stress, and energy absorption capacity of unreinforced foam samples improved linearly with increasing strain rate due to dynamic recrystallization and softening of the foam matrix material. The reinforced foam samples exhibit nonlinear deformation behavior. It was also found that the mechanical properties reduction of transverse reinforced foams was slightly lower compared to foams with longitudinal reinforcement at varying strain rates because of the large contribution of the mechanical properties of the reinforcement. The results of the present study can be employed to modelling and obtain impact-resistant fillers for complex structures in transport construction.
{"title":"Impact of the reinforced metal structure on the mechanical properties foamed aluminium composites at the load","authors":"O. Mareeva, V. Ermilov, V. Snezhko, D. Benin, A. Bakshtanin","doi":"10.1515/cls-2021-0026","DOIUrl":"https://doi.org/10.1515/cls-2021-0026","url":null,"abstract":"Abstract This paper is an experimental study of the quasi-static mechanical compressive properties of the reinforced closed-cell aluminum alloy foams with different cell orientations at different strain rates. The reinforced foam samples were obtained via the powder metallurgical route. The results of the compression tests revealed that the deformation behavior and mechanical properties of foamed aluminum composites are highly dependent on the orientation of the reinforcing mesh. Differences in the deformation behavior of foams appear to be influenced by the mechanical properties of the matrix material, by foam deformation mechanisms, and by the mechanical properties of the reinforcement. The yield stress, plateau stress, densification stress, and energy absorption capacity of unreinforced foam samples improved linearly with increasing strain rate due to dynamic recrystallization and softening of the foam matrix material. The reinforced foam samples exhibit nonlinear deformation behavior. It was also found that the mechanical properties reduction of transverse reinforced foams was slightly lower compared to foams with longitudinal reinforcement at varying strain rates because of the large contribution of the mechanical properties of the reinforcement. The results of the present study can be employed to modelling and obtain impact-resistant fillers for complex structures in transport construction.","PeriodicalId":44435,"journal":{"name":"Curved and Layered Structures","volume":"8 1","pages":"318 - 326"},"PeriodicalIF":1.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47845100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract This paper deals with the use of the shells in the architecture of concert halls through research on the historical development of the concert building’s space. These elements are widely applied in civil engineering and architecture due to the good operational qualities, very rich spectrum of forms, the simplicity of production and its technical efficiency. The article considers two types of shells: conoid and truncated cone to choose the most optimal form for covering the concert hall.
{"title":"The use of shells in the architecture of the concert halls","authors":"E. Ermakova, Marina I. Rynkovskaya","doi":"10.1515/cls-2021-0006","DOIUrl":"https://doi.org/10.1515/cls-2021-0006","url":null,"abstract":"Abstract This paper deals with the use of the shells in the architecture of concert halls through research on the historical development of the concert building’s space. These elements are widely applied in civil engineering and architecture due to the good operational qualities, very rich spectrum of forms, the simplicity of production and its technical efficiency. The article considers two types of shells: conoid and truncated cone to choose the most optimal form for covering the concert hall.","PeriodicalId":44435,"journal":{"name":"Curved and Layered Structures","volume":"8 1","pages":"61 - 69"},"PeriodicalIF":1.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1515/cls-2021-0006","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49127212","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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