Periodica Polytechnica (Budapest University of Technology and Economics)
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Parametric Study on the Effect of Axial Force on the Seismic Performance of the Bar Damper
Get PDFA bar damper (BD) is an energy-absorbing device that, despite its simplicity, exhibits excellent energy absorption capacity. The parametric studies in this research focused on the effect of axial force on the cyclic behavior of these dampers. Initially, to verify the results of the numerical model, three experimental BD samples with different heights were utilized. After calculating the buckling load of BD, the effect of 2% and 4% of this load on its cyclic behavior was investigated. The effect of axial force and damper dimensions on its seismic parameters was assessed through nonlinear static analyses. These parameters included initial and effective stiffness, strength, energy dissipation, and equivalent damping ratio (EDR). Additionally, based on the curve fitting method for estimating the initial stiffness of the damper under axial force, an approximate equation was provided, which showed acceptable accuracy compared to the numerical results. The results indicated that the axial force led to a reduction in elastic stiffness, effective stiffness, and strength of the damper, especially at large deformations. The impact on energy dissipation was negligible, but it caused an increase in the EDR. The greatest impact of the axial force was observed on the strength, followed by its effect on the EDR
Producing Concrete Incorporating Hybrid Cementitious Materials and Recycled Concrete Aggregate with Novel Thermal Treatment Methods
Get PDFRecycled concrete aggregate (RCA), characterized by high porosity and adhered mortar, often impairs the mechanical strength and durability of concrete. This research develops a new integrated treatment method, which combines thermal-mechanical conditioning of RCA with hybrid supplementary cementitious materials (SCMs), including metakaolin (MK) and ground granulated blast-furnace slag (GGBS). Three thermal treatment protocols were applied to enhance RCA quality, and concrete mixes with 50% and 100% RCA replacement were prepared. The study investigated the impact of adding MK up to 30% and GGBS up to 20% on the compressive strength, splitting tensile strength, workability, and water absorption of concrete. Although isolated effects require further investigation, the research found that the integrated use of TT3-treated RCA, where TT3 refers to the stepped thermal treatment protocol and SCMs, showed promising performance under the experimental conditions, producing a 90-day compressive strength greater than that of the control mix and reducing water absorption by more than 30%. The combined application of thermal-mechanical treatment (TT3) on RCA and the use of hybrid supplementary cementitious materials (SCMs), such as metakaolin (MK) and ground granulated blast-furnace slag (GGBS), significantly improved the concrete properties. The integrated use of TT3-treated RCA and SCMs resulted in a 90-day compressive strength that was 5.5% higher than that of the control mix, indicating significant long-term performance improvements
The Role of the Structural Model in Monument Value Preservation: Failure Mechanisms and Restoration Options from a Heritage Conservation Perspective
Get PDFThe separation of engineering and architectural perspectives in the 20th century led to the delegation of different aspects of building design to specialized professionals. Consequently, structural, architectural, and heritage preservation tasks were handled independently, creating diverse prioritization orders in the evaluation of the buildings. One of the greatest victims of this approach are heritage buildings, as less constructive collaborations can result in lasting damages, leading to the loss of certain values.In heritage preservation projects the structural model is typically less regarded as a value, often leading to a reconstruction without consideration of the original state. This significantly impacts the timber roofs, which are one of the most vulnerable building structures and their deformations can affect the entire building, underscoring the critical importance of preserving the original structural model and raising awareness of its significance as a heritage value.This research examines roof structure damages, their categorization from a structural perspective, and possible restoration options considering heritage preservation criteria. Through the examples presented, it becomes evident that the roof structures can only be understood as parts of a complex system. It also becomes apparent that due to this complexity, categorizing structural damages in heritage buildings does not help in making schematic solutions.For every heritage building a thorough investigation and understanding of the historical structural model, the examination of building structures and their interconnections, and the preparation of a reconstruction plan are essential. This process must acknowledge that both the building and its structural model require a unique approach
Assessing the Impact of High-Speed Rail Development on Conventional Passenger Trains and Sustainability of Transportation in Indonesia
Get PDFThere are many studies on the impact of high-speed rail (HSR) on airplane travel demand, economic growth, connectivity, accessibility, and regional development. However, the degrees to which HSR affects the demand for conventional passenger trains and operation of conventional rail are rarely discussed. This study attempted to fill this gap by identifying and investigating the potential impact of introducing a high-speed rail network in Indonesia, focusing on its implications for conventional passenger trains and the overall sustainability of the transportation system, utilizing an origin-destination matrix, a stated preference survey and choice analysis. The results show that fare is an influential attribute compared to travel time. High-speed trains are substitutes for medium to long distance and complementary for short distance travel. The study provides valuable insights for transport operators, policymakers, and planners. Key findings include a nuanced understanding of potential demands, travel attributes, strategic considerations for optimizing HSR operational plans and sustainable transport
Current trends in library and information science in the light of PhD research and studies – 6.: Interview with László Nemes
No full textThe editorial team of CELISR conducted a short interview with recent graduates of the Library and Information Science doctoral program at the ELTE Doctoral School of Literary Studies, in order to provide the journal’s readers with an insight into the current and future scientific activities of researchers, and to give an idea of the current research trends in the field. The following article contains a brief overview of the PhD research conducted by László Nemes, with background and future prospects.The editorial team of CELISR conducted a short interview with recent graduates of the Library and Information Science doctoral program at the ELTE Doctoral School of Literary Studies, in order to provide the journal’s readers with an insight into the current and future scientific activities of researchers, and to give an idea of the current research trends in the field. The following article contains a brief overview of the PhD research conducted by László Nemes, with background and future prospects
Statistical Libraries in Transition A 2024 European Survey on Future Directions and Opportunities
No full textThe study presents and evaluates the findings of a 2024 survey conducted among European statistical libraries, summarizing their most important attributes and information regarding to them. In addition to outlining the current state of this specialized type of library in Europe, the authors also explore potential directions for their future development, placing particular emphasis on the relationship between statistical libraries and their parent institutions, the national statistical offices