@article{MTMT:35509937, title = {Probabilistic failure assessment of steel eyebars by considering multi-phase nonlinear corrosion model}, url = {https://m2.mtmt.hu/api/publication/35509937}, author = {Kövesdi, Balázs Géza and Kollár, Dénes and Szabó, B. and Dunai, László}, doi = {10.1016/j.jcsr.2024.109127}, journal-iso = {J CONSTR STEEL RES}, journal = {JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH}, volume = {224}, unique-id = {35509937}, issn = {0143-974X}, year = {2025}, eissn = {1873-5983}, orcid-numbers = {Kövesdi, Balázs Géza/0000-0002-0370-2820; Kollár, Dénes/0000-0002-0048-3327; Dunai, László/0000-0002-1018-2413} } @article{MTMT:35667978, title = {Investigation of Separating Temperature-Induced Structural Strain Using Improved Blind Source Separation (BSS) Technique}, url = {https://m2.mtmt.hu/api/publication/35667978}, author = {Gu, Hao’an and Zhang, Xin and Sumarac, Dragoslav and Peng, Jiayi and Dunai, László and Zhang, Yufeng}, doi = {10.3390/s24248015}, journal-iso = {SENSORS-BASEL}, journal = {SENSORS}, volume = {24}, unique-id = {35667978}, abstract = {The strain data acquired from structural health monitoring (SHM) systems of large-span bridges are often contaminated by a mixture of temperature-induced and vehicle-induced strain components, thereby complicating the assessment of bridge health. Existing approaches for isolating temperature-induced strains predominantly rely on statistical temperature–strain models, which can be significantly influenced by arbitrarily chosen parameters, thereby undermining the accuracy of the results. Additionally, signal processing techniques, including empirical mode decomposition (EMD) and others, frequently yield unstable outcomes when confronted with nonlinear strain signals. In response to these challenges, this study proposes a novel temperature-induced strain separation technique based on improved blind source separation (BSS), termed the Temperature-Separate Second-Order Blind Identification (TS-SOBI) method. Numerical verification using a finite element (FE) bridge model that considers both temperature loads and vehicle loads confirms the effectiveness of TS-SOBI in accurately separating temperature-induced strain components. Furthermore, real strain data from the SHM system of a long-span bridge are utilized to validate the application of TS-SOBI in practical engineering scenarios. By evaluating the remaining strain components after applying the TS-SOBI method, a clearer understanding of changes in the bridge’s loading conditions is achieved. The investigation of TS-SOBI introduces a novel perspective for mitigating temperature effects in SHM applications for bridges. © 2024 by the authors.}, keywords = {temperature effect; FOUNDATIONS; health monitoring; Building materials; Blind source separation; Blind source separation; Separation techniques; Temperature-induced; EMPIRICAL MODE DECOMPOSITION; structural health monitoring; Structural health; strain gauges; Strain components; Second-order blind identification; Strain-gages; Induced strain; bridge strain separation; temperature-induced strain; Bridge components; Bridge strain separation; Second order blind identifications; Temperature-induced strain}, year = {2024}, eissn = {1424-8220}, orcid-numbers = {Dunai, László/0000-0002-1018-2413} } @article{MTMT:35593680, title = {Improvement of Stockbridge Damper Design for Cable-Stayed Bridges}, url = {https://m2.mtmt.hu/api/publication/35593680}, author = {Olosz, Adél and Kövesdi, Balázs Géza and Hegyi, Péter and Dunai, László}, doi = {10.3390/applmech5040046}, journal-iso = {APPLI MECH}, journal = {APPLIED MECHANICS}, volume = {5}, unique-id = {35593680}, abstract = {Stockbridge dampers are widely used to mitigate the vibrations of cable-stayed bridges and of many other cable-suspended or cable structures exposed to the action of pedestrians, traffic or wind load. Within the current research work, one of the most effective and likely used damper types, the Stockbridge damper, was investigated to support its design and application within the daily engineering praxis. The Stockbridge damper has a relatively simple structural layout, which ensures its modular design allows it to easily adapt the damper to cables having different dynamic properties (eigenfrequencies, mass, etc.). This paper focuses on two main research areas: (i) to understand the static and dynamic behaviour of the damper and the stay cable interaction to investigate the effectiveness of its damping; (ii) to study the sensitivity of the natural frequencies of the damper to the design parameters. The final aim of the research is to develop a simple design method that is easy to apply in engineering practice and allows the efficient adaptation of the Stockbridge damper to different cable-stayed bridges. Key findings include the recommendation to position the damper at approximately 20% of the cable length for optimal attenuation, the importance of detuning to maintain effectiveness under varying cable forces, and the observation that increasing the damper mass improves efficiency, particularly for detuned elements.}, year = {2024}, eissn = {2673-3161}, pages = {818-838}, orcid-numbers = {Olosz, Adél/0009-0000-2820-1347; Kövesdi, Balázs Géza/0000-0002-0370-2820; Hegyi, Péter/0000-0002-7230-5968; Dunai, László/0000-0002-1018-2413} } @inproceedings{MTMT:35172394, title = {Risk assessment of the K-bridge over the Danube}, url = {https://m2.mtmt.hu/api/publication/35172394}, author = {Kövesdi, Balázs Géza and Kollár, Dénes and Dunai, László and Hodik, Z.}, booktitle = {Bridge Maintenance, Safety, Management, Digitalization and Sustainability}, doi = {10.1201/9781003483755-383}, unique-id = {35172394}, abstract = {The K-bridge spans over the Danube between Buda and the Hajógyári Island in Budapest, Hungary. The originally railway, recently mixed road and pedestrian bridge have a more than 70-year-old steel truss main girder with a span of 98.04 m and a steel-concrete deck system. It plays an important role in Budapest city life and is heavily used during the Sziget festival, one of the biggest festivals in Europe. In 2022, during the regular bridge inspection, heavy corrosion and material loss were found by the experts in the bridge deck system and on the steel cantilever beams under the pedestrian walkways. The Budapest University of Technology and Economics (BME), Department of Structural Engineering together with design and maintenance experts investigated the condition of the structure and made a probabilistic analysis to verify the resistance of the corroded structure and made the risk assessment before the organization of the Sziget festival. The main aim of the analysis was the assessment of the load-bearing capacity of the corroded structure and determination of its risk against possible failure, based on the survey results of the current corrosion condition. Detailed inspection, on-site geometrical and corrosion measurements and partial loading tests were executed on the structure, which results served as input data of the probabilistic analysis. Advanced numerical models are developed to accurately calculate the load-bearing capacity of the heavily damaged structural details of the bridge by using stochastic analysis combining geometrical and material nonlinear analysis using imperfections (GMNIA). Based on the investigations, the necessary short-term and long-term maintenance tasks could be identified to be carried out on the bridge to ensure safe operation of the structure during the Sziget festival and to prolong the service lifetime of the bridge. © 2024 The Author(s).}, keywords = {Hungary; risk assessment; Budapest; Structural design; Stochastic models; stochastic systems; Nonlinear analysis; Probabilistic analysis; Loads (forces); Bearing capacity; Load-bearing capacity; Steel corrosion; Bridge decks; condition; footbridges; steel truss; Risks assessments; Bridge spans; Corroded structures; Steel concrete}, year = {2024}, pages = {3231-3239}, orcid-numbers = {Kövesdi, Balázs Géza/0000-0002-0370-2820; Kollár, Dénes/0000-0002-0048-3327; Dunai, László/0000-0002-1018-2413} } @article{MTMT:35172374, title = {Push-out tests of demountable shear connectors for sustainable composite structures}, url = {https://m2.mtmt.hu/api/publication/35172374}, author = {Király, Krisztián and Dunai, László and Calado, Luis and Kocsis, András Balázs}, doi = {10.1002/stco.202300044}, journal-iso = {STEEL CONSTR DES RES}, journal = {STEEL CONSTRUCTION-DESIGN AND RESEARCH}, volume = {17}, unique-id = {35172374}, issn = {1867-0520}, abstract = {The demountable shear connector is the most important component of sustainable composite structures, as it allows the elements to be reused. The ongoing research and development project – in the cooperation of the Budapest University of Technology and Economics and KÉSZ Group, bim.GROUP Ltd., Hungary – aims to design a new demountable steel-concrete composite structural system. In the current research, bolted shear connectors with embedded bolts and threaded rods, which can fit the applied technology of the industrial partner, are being developed and studied. One of the main aspects of this connection is to consider the bolt hole clearance – to decrease initial slip and stiffness reduction – and also to provide the proper strength and ductility features. A push-out experimental programme was designed and completed to study the behaviour of the developed shear connections. It is observed that the examined shear connectors have proper structural behaviour with adequate resistance and ductility, which is applicable according to the Eurocode 4 standard and fits the objectives of the current research project. This paper presents the developed structural details, the observations and the evaluation of the push-out experimental results with the conclusions and statements. © 2024 The Authors. Published by Ernst & Sohn GmbH.}, keywords = {Hungary; DUCTILITY; Economics; Structure (composition); shear flow; Architectural design; Industrial research; Research and development projects; Composite structures; Budapest University; Bolts; push-out test; 'current; Shear Connector; Shear Connector; Push-out tests; Composites structures; sustainable structure; sustainable structure; demountable composite structure; demountable composite structure; Pushouts}, year = {2024}, eissn = {1867-0539}, pages = {200-211}, orcid-numbers = {Dunai, László/0000-0002-1018-2413} } @article{MTMT:35166747, title = {Formulation of dynamic damage features sensitive to local fatigue cracks in steel bridges: Numerical study}, url = {https://m2.mtmt.hu/api/publication/35166747}, author = {Wei, Qingyang and Kövesdi, Balázs Géza and Dunai, László and Cao, Maosen}, doi = {10.1016/j.istruc.2024.107049}, journal-iso = {STRUCTURES}, journal = {STRUCTURES}, volume = {67}, unique-id = {35166747}, issn = {2352-0124}, year = {2024}, eissn = {2352-0124}, orcid-numbers = {Kövesdi, Balázs Géza/0000-0002-0370-2820; Dunai, László/0000-0002-1018-2413} } @article{MTMT:35092889, title = {Quantitative evaluation on the effects of the spatial variability in concrete materials on seismic damage of concrete gravity dams}, url = {https://m2.mtmt.hu/api/publication/35092889}, author = {Wei, Qingyang and Shen, Lei and Dunai, László and Kövesdi, Balázs Géza and Elqudah, Sara and Cao, Maosen}, doi = {10.1016/j.engfracmech.2024.110287}, journal-iso = {ENG FRACT MECH}, journal = {ENGINEERING FRACTURE MECHANICS}, volume = {307}, unique-id = {35092889}, issn = {0013-7944}, year = {2024}, eissn = {1873-7315}, orcid-numbers = {Dunai, László/0000-0002-1018-2413; Kövesdi, Balázs Géza/0000-0002-0370-2820; Cao, Maosen/0000-0003-3268-3646} } @{MTMT:35080955, title = {Javított tulajdonságú rezgéscsillapító egység feszített kábelekhez, különösen hídkábelekhez}, url = {https://m2.mtmt.hu/api/publication/35080955}, author = {Csohány, András and Medveczki, István and Dunai, László and Pál, Gábor and Gosztola, Dániel and Hegyi, Péter and Kemenczés, András and Kollár, László Péter and Kövesdi, Balázs Géza}, unique-id = {35080955}, year = {2024}, orcid-numbers = {Dunai, László/0000-0002-1018-2413; Hegyi, Péter/0000-0002-7230-5968; Kollár, László Péter/0000-0001-9313-2296; Kövesdi, Balázs Géza/0000-0002-0370-2820} } @article{MTMT:34839813, title = {Analysis of dynamic features on local fatigue cracks in steel bridges}, url = {https://m2.mtmt.hu/api/publication/34839813}, author = {Wei, Qingyang and Kövesdi, Balázs Géza and Cao, Maosen and Dunai, László}, doi = {10.1016/j.prostr.2024.03.028}, journal-iso = {PROCEDIA STRUCT INTEGRITY}, journal = {PROCEDIA STRUCTURAL INTEGRITY}, volume = {57}, unique-id = {34839813}, issn = {2452-3216}, abstract = {In steel bridges with orthotropic decks, a common and important engineering structure, fatigue cracks can appear under long-term operation. Existing artificial detection is the main approach to detecting fatigue cracks in steel bridges, in addition to some non-destructive testing or image processing methods, and unmanned aerial vehicle are applied to improve accuracy and efficiency. However, the detection of fatigue cracks in steel bridges based on the variation of dynamic responses or dynamic parameters is another attractive idea, which is still rarely mentioned and investigated in the international literature. The reason is that local cracks usually have negligible effect on the global dynamic characteristics of steel bridges, resulting in the insensitivity to dynamic indexes to fatigue cracks. On this occasion, this study numerically explores and establishes two sensitive damage features to local damage, i.e., the crack in the vertical rib, based on the fatigue cracks found on the Türr Istvan bridge over the Danube River in Hungary. The local vibrations of the bridge are excited through the local impact on the structural details, i.e., the vertical rib, and then the high-order frequencies of the entire bridge are examined. The obtained high-order frequencies are proved to be more sensitive to the fatigue cracks on vertical ribs and increased with the crack depths. On the other hand, the correlation of the stress curves on opposite sides of the crack is sensitive to the depth of the crack. If fatigue cracks are found, the development degree of the fatigue cracks can be monitored more accurately by focusing on the correlation of local stresses near the crack. These two damage features are numerically proven to have feasibility and are expected to break through the insensitivity of the existing dynamic detection methods. © 2024 The Authors. Published by Elsevier B.V.}, year = {2024}, pages = {262-270}, orcid-numbers = {Kövesdi, Balázs Géza/0000-0002-0370-2820; Dunai, László/0000-0002-1018-2413} } @article{MTMT:34727225, title = {Experimental Study of Novel Demountable Shear Connectors for Steel-concrete Composite Buildings}, url = {https://m2.mtmt.hu/api/publication/34727225}, author = {Király, Krisztián and Dunai, László}, doi = {10.3311/PPci.22732}, journal-iso = {PERIOD POLYTECH CIV ENG}, journal = {PERIODICA POLYTECHNICA-CIVIL ENGINEERING}, volume = {68}, unique-id = {34727225}, issn = {0553-6626}, abstract = {Sustainable composite structures in building construction are assembled using demountable structural elements that can be reused in the circular economy. The current research and development project, in cooperation with Budapest University of Technology and Economics and KeSZ Group, bim.GROUP Ltd., Hungary, aims to design a novel demountable steel-concrete composite slab and frame system for buildings. The key component of this construction is the demountable shear connector. In the current research, novel bolted shear connectors with embedded bolts and threaded rods are developed and studied that can fit the applied technology of the industrial partner. One of the leading aspects of this connection is the consideration of bolt hole clearance, since it occurs initial slip and stiffness reduction of the composite beam. In the first phase of the research program, demountable and economical structural details were developed, which can reduce the stiffness reduction with the proper resistance and ductility features. To study the behavior of these shear connections, a push-out experimental program was designed and completed in March and April 2023. It is observed that novel shear connectors have a proper behavior with sufficient resistance and ductility, which is applicable according to the Eurocode 4 standard and fits the objectives of the research and development project. In the paper, the developed structural details and the push-out experimental program are presented with general results and statements besides a detailed evaluation of a specified specimen type.}, keywords = {Shear Connector; sustainable structure; demountable composite structure}, year = {2024}, eissn = {1587-3773}, pages = {647-656}, orcid-numbers = {Dunai, László/0000-0002-1018-2413} }