Pub Date : 2024-09-03DOI: 10.1016/j.istruc.2024.107180
S.S. Zhang, D.D. Zhang, X.F. Nie, J.P. Ye
The principle of strong column and weak beam (SCWB) is often adopted in the design of reinforced concrete (RC) frames to ensure their optimum seismic performance. However, insufficient consideration of the SCWB hierarchy has resulted in numerous existing RC frames violating such a hierarchy. Consequently, a novel seismic retrofitting technique (section reduction technique) was proposed for RC frames that violate the SCWB hierarchy. The section reduction (SR) technique involves creating a locally reduced cross-sections (i.e., a gap) in the bottom region of the beam (i.e., the compression region of the beam under negative bending) adjacent to the beam-to-column joint and applying a fiber-reinforced polymer (FRP) strengthening system, which reduces the negative bending capacity of the beam while improving the shear capacity of the gap region. Nine full-size RC beams were fabricated and three-point negative bending experiments were conducted to demonstrate the validity of the SR technique. Based on the test results, it was found that a gap of appropriate size can effectively reduce the negative bending capacity of a T-shaped RC beam. In addition, the ductility of the beams can be ensured if the occurrence of FRP U-jacket debonding can be effectively prevented when applying the FRP strengthening system.
钢筋混凝土（RC）框架的设计通常采用强柱弱梁（SCWB）原则，以确保其达到最佳抗震性能。然而，由于没有充分考虑强柱弱梁的层次结构，导致许多现有的 RC 框架违反了这一层次结构。因此，针对违反 SCWB 层次结构的 RC 框架，提出了一种新的抗震改造技术（截面缩小技术）。截面减小（SR）技术包括在梁与柱连接处附近的梁底部区域（即负弯下梁的压缩区域）创建局部减小的截面（即间隙），并应用纤维增强聚合物（FRP）加固系统，从而减小梁的负弯承载力，同时提高间隙区域的抗剪承载力。为了证明 SR 技术的有效性，我们制作了九个全尺寸 RC 梁，并进行了三点负弯曲实验。测试结果表明，适当大小的间隙可有效降低 T 型 RC 梁的负弯曲能力。此外，在应用玻璃钢加固系统时，如果能有效防止玻璃钢 U 型夹层脱粘，则可确保梁的延展性。
{"title":"Experimental study on T-shaped reinforced concrete beams with locally reduced cross-sections","authors":"S.S. Zhang, D.D. Zhang, X.F. Nie, J.P. Ye","doi":"10.1016/j.istruc.2024.107180","DOIUrl":"https://doi.org/10.1016/j.istruc.2024.107180","url":null,"abstract":"The principle of strong column and weak beam (SCWB) is often adopted in the design of reinforced concrete (RC) frames to ensure their optimum seismic performance. However, insufficient consideration of the SCWB hierarchy has resulted in numerous existing RC frames violating such a hierarchy. Consequently, a novel seismic retrofitting technique (section reduction technique) was proposed for RC frames that violate the SCWB hierarchy. The section reduction (SR) technique involves creating a locally reduced cross-sections (i.e., a gap) in the bottom region of the beam (i.e., the compression region of the beam under negative bending) adjacent to the beam-to-column joint and applying a fiber-reinforced polymer (FRP) strengthening system, which reduces the negative bending capacity of the beam while improving the shear capacity of the gap region. Nine full-size RC beams were fabricated and three-point negative bending experiments were conducted to demonstrate the validity of the SR technique. Based on the test results, it was found that a gap of appropriate size can effectively reduce the negative bending capacity of a T-shaped RC beam. In addition, the ductility of the beams can be ensured if the occurrence of FRP U-jacket debonding can be effectively prevented when applying the FRP strengthening system.","PeriodicalId":48642,"journal":{"name":"Structures","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Beams and columns serve as foundational components within structures, bridges, and industrial machinery. Detecting even minor defects in these crucial elements before they escalate into more significant damage holds paramount importance. Employing an innovative methodology grounded in the two-dimensional discrete wavelet transform alongside curvature analysis, this study scrutinizes the one-dimensional mode shape signals extended to two-dimensional. More precisely, it introduces the Wavelet Expansion Index (WEI) and the Normalized Wavelet Discontinuity Index (NWDI) to effectively pinpoint various damage locations. Numerical and laboratory investigations demonstrate that fractures and discontinuities in the WEI graph and peaks arising from irregularities in the NWDI graph are generated. Consequently, damage locations are identified, such that using NWDI, damaged areas can be detected with an error of less than 4%.
{"title":"Vibration-based health monitoring and damage detection in beam-like structures with innovative approaches based on signal processing: A numerical and experimental study","authors":"Mohtasham Khanahmadi, Borhan Mirzaei, Behzad Dezhkam, Omid Rezaifar, Majid Gholhaki, Gholamreza Ghodrati Amiri","doi":"10.1016/j.istruc.2024.107211","DOIUrl":"https://doi.org/10.1016/j.istruc.2024.107211","url":null,"abstract":"Beams and columns serve as foundational components within structures, bridges, and industrial machinery. Detecting even minor defects in these crucial elements before they escalate into more significant damage holds paramount importance. Employing an innovative methodology grounded in the two-dimensional discrete wavelet transform alongside curvature analysis, this study scrutinizes the one-dimensional mode shape signals extended to two-dimensional. More precisely, it introduces the Wavelet Expansion Index (WEI) and the Normalized Wavelet Discontinuity Index (NWDI) to effectively pinpoint various damage locations. Numerical and laboratory investigations demonstrate that fractures and discontinuities in the WEI graph and peaks arising from irregularities in the NWDI graph are generated. Consequently, damage locations are identified, such that using NWDI, damaged areas can be detected with an error of less than 4%.","PeriodicalId":48642,"journal":{"name":"Structures","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-03DOI: 10.1016/j.istruc.2024.107190
Jakub Gašpárek, Peter Paulík, Denis Kopásek
During 2019 and 2020, several segmental post-tensioned bridges or footbridges collapsed in the Slovak Republic. As a result of this sequence of bridge collapses, an inspection of a large number of segmental post-tensioned structures has been carried out since 2022 in order to determine their condition and risk rating. The inspections were carried out by Slovak universities and private companies. The findings obtained from the targeted bridge diagnostics carried out by the Department of Concrete Structures and Bridges of the Slovak University of Technology in Bratislava are presented in this paper in the context of published international findings and reports. One of the main objectives was to investigate the post-tensioned tendons and to determine the possible absence of grouting, which has an impact on the determination of the risk rating of the bridges. The data obtained so far from Slovak bridges show that half of the inspected old post-tensioned bridges (built in the 1960s, 70 s and 80 s) have some percentage of tendons, which are only partially or, in some cases, completely ungrouted. As a result of these findings, in some cases, it was necessary to reduce the number of traffic lanes or the maximum permitted load of vehicles on the bridge. Even before the late stage of corrosion, visible phenomena on the concrete surface have been observed, showing the possibility of ungrouted and corroded tendons in the bridge. This paper summarises some of the problems of post-tensioned bridges and the state-of-the-art in prestress control. Following the brittle collapses of bridges that have occurred in Slovakia, the article complements some of the knowledge gained during the targeted diagnosis of post-tensioned segmental bridges also in the context of demolitions of some high-risk bridges that have been carried out.
{"title":"Findings from in-situ survey of post-tensioned precast and segmental post-tensioned bridges","authors":"Jakub Gašpárek, Peter Paulík, Denis Kopásek","doi":"10.1016/j.istruc.2024.107190","DOIUrl":"https://doi.org/10.1016/j.istruc.2024.107190","url":null,"abstract":"During 2019 and 2020, several segmental post-tensioned bridges or footbridges collapsed in the Slovak Republic. As a result of this sequence of bridge collapses, an inspection of a large number of segmental post-tensioned structures has been carried out since 2022 in order to determine their condition and risk rating. The inspections were carried out by Slovak universities and private companies. The findings obtained from the targeted bridge diagnostics carried out by the Department of Concrete Structures and Bridges of the Slovak University of Technology in Bratislava are presented in this paper in the context of published international findings and reports. One of the main objectives was to investigate the post-tensioned tendons and to determine the possible absence of grouting, which has an impact on the determination of the risk rating of the bridges. The data obtained so far from Slovak bridges show that half of the inspected old post-tensioned bridges (built in the 1960s, 70 s and 80 s) have some percentage of tendons, which are only partially or, in some cases, completely ungrouted. As a result of these findings, in some cases, it was necessary to reduce the number of traffic lanes or the maximum permitted load of vehicles on the bridge. Even before the late stage of corrosion, visible phenomena on the concrete surface have been observed, showing the possibility of ungrouted and corroded tendons in the bridge. This paper summarises some of the problems of post-tensioned bridges and the state-of-the-art in prestress control. Following the brittle collapses of bridges that have occurred in Slovakia, the article complements some of the knowledge gained during the targeted diagnosis of post-tensioned segmental bridges also in the context of demolitions of some high-risk bridges that have been carried out.","PeriodicalId":48642,"journal":{"name":"Structures","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Due to the low flexural strength of rammed earth, it is prone to flexural cracks under horizontal loads, necessitating the development of novel structural measures to enhance its flexural capacity. This study introduced the reinforcement of rammed earth structures with embedded steel reinforcement to improve their flexural performance. A series of two-point loading tests were conducted on 12 rammed earth beams to investigate the effects of polypropylene fiber content and steel reinforcement ratio on the deflection, cracking load, ultimate load, flexural toughness, and failure modes of the beams. Based on the assumption of the plane section, a design formula for the flexural capacity of reinforced rammed earth beams was proposed and validated against experimental results. The findings indicate that the addition of polypropylene fibers increased the cracking load, deformation capacity, and flexural toughness of the rammed earth beams by 14.8 %, 44.2 %, and 105.6 %, respectively. In contrast, the inclusion of steel reinforcement significantly enhanced the ultimate load, deformation capacity, and flexural toughness by 596.3 %, 607.0 %, and 4543.2 %, respectively, transforming the failure mode from brittle fracture to ductile flexural failure. The proposed formula was validated and can be effectively used to calculate the flexural capacity of reinforced rammed earth beams.
{"title":"Flexural capacity and failure trend of fiber and steel reinforcement reinforced cement stabilized rammed earth beams","authors":"Liangyi Zhang, Tiegang Zhou, Junhai Lu, Wei Tan, Zengfei Liang","doi":"10.1016/j.istruc.2024.107170","DOIUrl":"https://doi.org/10.1016/j.istruc.2024.107170","url":null,"abstract":"Due to the low flexural strength of rammed earth, it is prone to flexural cracks under horizontal loads, necessitating the development of novel structural measures to enhance its flexural capacity. This study introduced the reinforcement of rammed earth structures with embedded steel reinforcement to improve their flexural performance. A series of two-point loading tests were conducted on 12 rammed earth beams to investigate the effects of polypropylene fiber content and steel reinforcement ratio on the deflection, cracking load, ultimate load, flexural toughness, and failure modes of the beams. Based on the assumption of the plane section, a design formula for the flexural capacity of reinforced rammed earth beams was proposed and validated against experimental results. The findings indicate that the addition of polypropylene fibers increased the cracking load, deformation capacity, and flexural toughness of the rammed earth beams by 14.8 %, 44.2 %, and 105.6 %, respectively. In contrast, the inclusion of steel reinforcement significantly enhanced the ultimate load, deformation capacity, and flexural toughness by 596.3 %, 607.0 %, and 4543.2 %, respectively, transforming the failure mode from brittle fracture to ductile flexural failure. The proposed formula was validated and can be effectively used to calculate the flexural capacity of reinforced rammed earth beams.","PeriodicalId":48642,"journal":{"name":"Structures","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-02DOI: 10.1016/j.istruc.2024.107188
Onur Araz
Tuned mass damper is one of the effective methods used to reduce dynamic loads in structures under the influence of environmental loads such as earthquakes, wind, and traffic loads. In the current TMD design, the fixed base approach is mostly considered when determining the dynamic properties of the structure. However, in cases where the structure-soil interaction (SSI) is important, the frequency values of the structure are significantly different from those obtained for the fixed foundation approach. This situation negatively affects the performance of TMD operating in a narrow frequency range. Therefore, using a control system consisting of multiple TMDs connected in parallel (MTMD) instead of a single TMD may be a promising solution for the control of structural vibrations. In this study, a parameter design and efficiency assessment of MTMD for reducing the seismic responses of the structure considering SSI is studied. The particle swarm optimization (PSO) algorithm is adopted to obtain the optimum parameters (i.e., damping ratio, frequency ratio, and frequency bandwidth) of the MTMD. The effects of different support conditions, number of TMD units, and peak ground velocity (PGV) / peak ground acceleration (PGA) ratio on the performance of MTMD are also evaluated comprehensively. The dynamic responses of the structure are obtained under 42 near -fault ground motions from the time history analysis. The results reveal that ground motions with low PGV/PGA ratio can significantly increase the responses of the structure for both with and without SSI cases. Moreover, it has been observed that optimized TMDs placed parallel to the top floor of the structure are effective in reducing the seismic responses of a ten-story building considering SSI.
{"title":"Effect of PGV/PGA ratio on seismic-induced vibrations of structures equipped with parallel tuned mass dampers considering SSI","authors":"Onur Araz","doi":"10.1016/j.istruc.2024.107188","DOIUrl":"https://doi.org/10.1016/j.istruc.2024.107188","url":null,"abstract":"Tuned mass damper is one of the effective methods used to reduce dynamic loads in structures under the influence of environmental loads such as earthquakes, wind, and traffic loads. In the current TMD design, the fixed base approach is mostly considered when determining the dynamic properties of the structure. However, in cases where the structure-soil interaction (SSI) is important, the frequency values of the structure are significantly different from those obtained for the fixed foundation approach. This situation negatively affects the performance of TMD operating in a narrow frequency range. Therefore, using a control system consisting of multiple TMDs connected in parallel (MTMD) instead of a single TMD may be a promising solution for the control of structural vibrations. In this study, a parameter design and efficiency assessment of MTMD for reducing the seismic responses of the structure considering SSI is studied. The particle swarm optimization (PSO) algorithm is adopted to obtain the optimum parameters (i.e., damping ratio, frequency ratio, and frequency bandwidth) of the MTMD. The effects of different support conditions, number of TMD units, and peak ground velocity (PGV) / peak ground acceleration (PGA) ratio on the performance of MTMD are also evaluated comprehensively. The dynamic responses of the structure are obtained under 42 near -fault ground motions from the time history analysis. The results reveal that ground motions with low PGV/PGA ratio can significantly increase the responses of the structure for both with and without SSI cases. Moreover, it has been observed that optimized TMDs placed parallel to the top floor of the structure are effective in reducing the seismic responses of a ten-story building considering SSI.","PeriodicalId":48642,"journal":{"name":"Structures","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-02DOI: 10.1016/j.istruc.2024.107203
Le-Hung Tran, Tuan-Manh Duong, Tien Hoang, Gilles Foret, Denis Duhamel
The railway track consists of two rails which are solicited the loads from passing trains. Due to the dynamic nature of these loads, the total forces applied to each rail are unequal and asymmetric. However, analytical models that simplify the track as a single beam cannot accurately describe the track responses. In this paper, we calculate the forced vertical vibration of a ballasted railway track subjected to dynamic loading with dual rails. Each rail is modelled as a uniform Euler–Bernoulli beam of infinite length, positioned on a system of periodic and identical supports. The forced vibration of the rail is determined using Floquet’s theorem. Additionally, a model of a beam on a continuous foundation is employed to describe the dynamic behaviour of each support. In the frequency domain, each support is represented as a spring with an equivalent stiffness. By combining these two developed models, we analytically obtain the forced vibrations of two rails in the frequency domain. In the symmetric configuration, our results show a similarity of the rail responses with an existing model, particularly at the pin-pin resonance. The differing peak resonances at low-band frequencies are attributed to the different types of support. Subsequently, we apply this new model to investigate the forced vibrations of two rails in a non-symmetric configuration. The numerical tool visually illustrates the influence of load positions on rail responses and reaction forces in the time domain. This analytical model proves valuable for studying the rail noise and vibration of ballasted railway tracks.
{"title":"An analytical model to calculate the forced vertical vibrations of two rails subjected to the dynamic loads of ballasted railway track","authors":"Le-Hung Tran, Tuan-Manh Duong, Tien Hoang, Gilles Foret, Denis Duhamel","doi":"10.1016/j.istruc.2024.107203","DOIUrl":"https://doi.org/10.1016/j.istruc.2024.107203","url":null,"abstract":"The railway track consists of two rails which are solicited the loads from passing trains. Due to the dynamic nature of these loads, the total forces applied to each rail are unequal and asymmetric. However, analytical models that simplify the track as a single beam cannot accurately describe the track responses. In this paper, we calculate the forced vertical vibration of a ballasted railway track subjected to dynamic loading with dual rails. Each rail is modelled as a uniform Euler–Bernoulli beam of infinite length, positioned on a system of periodic and identical supports. The forced vibration of the rail is determined using Floquet’s theorem. Additionally, a model of a beam on a continuous foundation is employed to describe the dynamic behaviour of each support. In the frequency domain, each support is represented as a spring with an equivalent stiffness. By combining these two developed models, we analytically obtain the forced vibrations of two rails in the frequency domain. In the symmetric configuration, our results show a similarity of the rail responses with an existing model, particularly at the pin-pin resonance. The differing peak resonances at low-band frequencies are attributed to the different types of support. Subsequently, we apply this new model to investigate the forced vibrations of two rails in a non-symmetric configuration. The numerical tool visually illustrates the influence of load positions on rail responses and reaction forces in the time domain. This analytical model proves valuable for studying the rail noise and vibration of ballasted railway tracks.","PeriodicalId":48642,"journal":{"name":"Structures","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The performances of gridshells depend on the grid topology but also the geometry of the underlying surface. In optimal design, such as funicular shapes, topology and geometry are linked. When lifting a grid, the resulting shape depends on the provided topology. Topology generation is thus a tool for structural design. This paper shows its practical application for engineers. The topology generation method described in Boutillier et al. (2024b) is employed and provides grids adapted to the support conditions of the project. Grids are then lifted and evaluated in two case studies: the spatial forms result from an optimisation process balancing surface funicularity with panel planarity. In the first case, the mechanical performances are then evaluated according to different criteria. A non-intuitive result shows that a large variety of topologies is situated on the Pareto front, legitimating a posteriori the topology generation method. In the second case, the method’s applicability is evaluated through the fabrication of a wooden pavilion with a funicular structure and flat quadrilateral panels, making it possible to reconcile topology with manufacturing and project constraints.
{"title":"Coupling grid topology generation and form-finding for the design of architectural meshes","authors":"Romane Boutillier, Cyril Douthe, Laurent Hauswirth, Olivier Baverel","doi":"10.1016/j.istruc.2024.107119","DOIUrl":"https://doi.org/10.1016/j.istruc.2024.107119","url":null,"abstract":"The performances of gridshells depend on the grid topology but also the geometry of the underlying surface. In optimal design, such as funicular shapes, topology and geometry are linked. When lifting a grid, the resulting shape depends on the provided topology. Topology generation is thus a tool for structural design. This paper shows its practical application for engineers. The topology generation method described in Boutillier et al. (2024b) is employed and provides grids adapted to the support conditions of the project. Grids are then lifted and evaluated in two case studies: the spatial forms result from an optimisation process balancing surface funicularity with panel planarity. In the first case, the mechanical performances are then evaluated according to different criteria. A non-intuitive result shows that a large variety of topologies is situated on the Pareto front, legitimating a posteriori the topology generation method. In the second case, the method’s applicability is evaluated through the fabrication of a wooden pavilion with a funicular structure and flat quadrilateral panels, making it possible to reconcile topology with manufacturing and project constraints.","PeriodicalId":48642,"journal":{"name":"Structures","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-02DOI: 10.1016/j.istruc.2024.107151
Chenyang Wei, Changyong Liu, Qing Hu, Daiyu Wang, Yuyin Wang
In order to address corrosion issues in concrete-filled steel tubular (CFST) arches, the fiber reinforced polymer (FRP) confined concrete-filled steel tubular (CCFST) arch, consisting of an FRP-steel composite tube and a core concrete, are proposed in this paper. To investigate the in-plane behaviors of CCFST parabolic arches, one bare CFST arch and five CCFST arches with a span of 6 m were tested and analyzed under the mid-span concentrated load. The main parameters considered in the test included various FRP wrapping methods (spiral winding, longitudinal and spiral winding, and braided shell) and different rise-to-span ratios (1/8, 1/6 and 1/4). The failure patterns and mechanisms were studied, and the confining effect of FRP-steel composite tube to the concrete at failure was investigated. The test results showed that the CCFST arch with spiral winding exhibited symmetric instability failure, akin to CFST arches; whereas CCFST arches with longitudinal winding failed due to the sudden rupture of longitudinally wrapped FRP strips. In addition, the finite element model of CCFST arches was established with solid element and verified based on test results. The parametric analysis indicated that the in-plane bearing capacity of CCFST arches under mid-span concentrated loads increased with the increase of the FRP layers, the rise-to-span ratio and the steel ratio, but decreases with the increase of the slenderness ratio.
{"title":"In-plane behaviors of FRP confined concrete-filled steel tubular arches under mid-span concentrated loads","authors":"Chenyang Wei, Changyong Liu, Qing Hu, Daiyu Wang, Yuyin Wang","doi":"10.1016/j.istruc.2024.107151","DOIUrl":"https://doi.org/10.1016/j.istruc.2024.107151","url":null,"abstract":"In order to address corrosion issues in concrete-filled steel tubular (CFST) arches, the fiber reinforced polymer (FRP) confined concrete-filled steel tubular (CCFST) arch, consisting of an FRP-steel composite tube and a core concrete, are proposed in this paper. To investigate the in-plane behaviors of CCFST parabolic arches, one bare CFST arch and five CCFST arches with a span of 6 m were tested and analyzed under the mid-span concentrated load. The main parameters considered in the test included various FRP wrapping methods (spiral winding, longitudinal and spiral winding, and braided shell) and different rise-to-span ratios (1/8, 1/6 and 1/4). The failure patterns and mechanisms were studied, and the confining effect of FRP-steel composite tube to the concrete at failure was investigated. The test results showed that the CCFST arch with spiral winding exhibited symmetric instability failure, akin to CFST arches; whereas CCFST arches with longitudinal winding failed due to the sudden rupture of longitudinally wrapped FRP strips. In addition, the finite element model of CCFST arches was established with solid element and verified based on test results. The parametric analysis indicated that the in-plane bearing capacity of CCFST arches under mid-span concentrated loads increased with the increase of the FRP layers, the rise-to-span ratio and the steel ratio, but decreases with the increase of the slenderness ratio.","PeriodicalId":48642,"journal":{"name":"Structures","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-02DOI: 10.1016/j.istruc.2024.107191
Jiulin Bai, Weichao Xu, Jing He, Huiming Chen
Seismic damage-controllable components and design approaches are crucial for achieving the seismic resilience and post-earthquake recovery of building structures. To improve the seismic resilience of reinforced concrete (RC) frame structures, this study proposed a novel assembled replaceable rocking column foot joint. The column foot joint is composed of a concrete foundation, short steel-tube concrete column in the center, and four new buckling-restrained steel plates (BRSPs) on the periphery. A detailed design method for the BRSPs was developed, and six BRSP specimens were designed with different core weakening forms and thicknesses. The specimens were cyclically tested and the failure mode and hysteresis behavior were examined. The test results confirmed that the proposed BRSPs exhibit satisfactory energy-dissipation capacity and achieve damage control. The refined numerical models were developed using ABAQUS and verified using the test results. Parametric analyses were conducted for the BRSPs to examine the influence of core plate thickness, gap size, and restraint plate thickness. A numerical analysis model of the column foot joint was established, and the influence of the axial compression ratio and BRSP bearing capacity on the seismic performance of the column foot was investigated. This study provides a reference for the construction of resilient RC frame structures.
{"title":"Seismic performance investigation of new buckling-restrained steel plate for resilient rocking column foot joint","authors":"Jiulin Bai, Weichao Xu, Jing He, Huiming Chen","doi":"10.1016/j.istruc.2024.107191","DOIUrl":"https://doi.org/10.1016/j.istruc.2024.107191","url":null,"abstract":"Seismic damage-controllable components and design approaches are crucial for achieving the seismic resilience and post-earthquake recovery of building structures. To improve the seismic resilience of reinforced concrete (RC) frame structures, this study proposed a novel assembled replaceable rocking column foot joint. The column foot joint is composed of a concrete foundation, short steel-tube concrete column in the center, and four new buckling-restrained steel plates (BRSPs) on the periphery. A detailed design method for the BRSPs was developed, and six BRSP specimens were designed with different core weakening forms and thicknesses. The specimens were cyclically tested and the failure mode and hysteresis behavior were examined. The test results confirmed that the proposed BRSPs exhibit satisfactory energy-dissipation capacity and achieve damage control. The refined numerical models were developed using ABAQUS and verified using the test results. Parametric analyses were conducted for the BRSPs to examine the influence of core plate thickness, gap size, and restraint plate thickness. A numerical analysis model of the column foot joint was established, and the influence of the axial compression ratio and BRSP bearing capacity on the seismic performance of the column foot was investigated. This study provides a reference for the construction of resilient RC frame structures.","PeriodicalId":48642,"journal":{"name":"Structures","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-02DOI: 10.1016/j.istruc.2024.107183
Yulin Xiong, Hongjia Lu, Yi Min Xie
Utilising topology optimisation to generate diverse and competitive structures enables designers to create elegant and efficient designs according to their aesthetic intuition and functional needs. This study proposes load and support perturbation approaches based on the bi-directional evolutionary structural optimisation (BESO) method to achieve diverse designs. During the optimisation process, noise is introduced to the sensitivity calculations by randomly perturbing the load angles or material properties near the supports, leading to a variety of local optima. Numerical results demonstrate that the proposed approaches are capable of creating designs with similar stiffness but distinct geometries. In addition, the diversity of the obtained solutions can be controlled by utilising different perturbation functions. This work is of significant practical importance in both architecture and engineering, where multiple design options of high structural performance are in demand.
{"title":"Perturbation approaches to achieving diverse and competitive designs in topology optimisation","authors":"Yulin Xiong, Hongjia Lu, Yi Min Xie","doi":"10.1016/j.istruc.2024.107183","DOIUrl":"https://doi.org/10.1016/j.istruc.2024.107183","url":null,"abstract":"Utilising topology optimisation to generate diverse and competitive structures enables designers to create elegant and efficient designs according to their aesthetic intuition and functional needs. This study proposes load and support perturbation approaches based on the bi-directional evolutionary structural optimisation (BESO) method to achieve diverse designs. During the optimisation process, noise is introduced to the sensitivity calculations by randomly perturbing the load angles or material properties near the supports, leading to a variety of local optima. Numerical results demonstrate that the proposed approaches are capable of creating designs with similar stiffness but distinct geometries. In addition, the diversity of the obtained solutions can be controlled by utilising different perturbation functions. This work is of significant practical importance in both architecture and engineering, where multiple design options of high structural performance are in demand.","PeriodicalId":48642,"journal":{"name":"Structures","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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