Periodica Polytechnica (Budapest University of Technology and Economics)
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Bod Péter Országos Könyvtárhasználati Verseny: új szervezőkkel is a hagyomány és a minőség útján
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Probabilistic Seismic Performance Assessment of Tall RC Special Moment-resisting Frame Buildings Equipped with Buckling-restrained Braces under Near-field Excitations
Get PDFMany tall buildings have already been constructed near faults throughout the world, several of which have sustained casualties and economic losses during strong ground motions. This study investigates the effect of near-fault excitations on the vulnerability of tall, reinforced concrete (RC) special moment-resisting frame (SMRF) buildings equipped with buckling-restrained braces (BRBs) using seismic fragility curves. After attaining the structure’s response modification factor (R), three-dimensional (3D) models of 15-, 25- and 35-story frames were developed by the OpenSees software according to the Iranian code provisions. Thus, the seismic response of the elements was obtained. Subsequently, incremental dynamic analysis (IDA) was conducted by selecting a suitable number of compatible accelerograms in two near-field and far-field groups. Considering the maximum story drift as the demand parameter and selecting the interstory drift ratios (IDR) for the slight, moderate, extensive, and complete collapse seismic performance levels proposed by Hazus, IDA curves were plotted. Then, the seismic fragility curves were produced using the structural reliability relations. The median fragility at complete collapse damage level reduced from 0.73g, 0.62g, and 0.61g to 0.68g, 0.59, and 0.57g for the 15-, 25, and 35-story near-field and far-field earthquake models, respectively. This was attributed to increasing vulnerability and seismic fragility of the structures as a result of both height increase and distance reduction from fault. Based on the results, the most vulnerable structure, i.e., the 35-story near-fault model, experienced a 40, 17, 18, and 6% increase in median fragility at slight, moderate, extensive, and complete collapse damage levels, respectively
Impact of Ambient Temperature, Passenger Load, and Delay on the Consumption of Battery Electric Buses
Get PDFThe operation of state-of-the-art battery electric buses (BEBs) has started recently, and their consumption model is unknown. Therefore, the service providers are lenient regarding the energy used. Our aim was to reveal the effects of ambient temperature and bus service characteristics, such as passenger load and delay, on the energy consumption. Real-time consumption data of BEBs were analyzed in Nyíregyháza, Hungary, and the functional relationships among the aforementioned variables were revealed. We found that while ambient temperature is negatively correlated with consumption in the cold winter periods, the consumption surplus is positively correlated with passenger load and generally positively correlated with the delay on the trip because of road traffic. In the case of delay, the consumption increase is caused by more frequent acceleration and the greater consumption of auxiliary systems due to longer running times. Accordingly, the energy consumption can be estimated if the characteristics data are available. The results can be used by bus service operators to plan the daily schedule and predict the energy consumption of a BEB
Multi-objective Colliding Bodies Optimization Algorithm for the Obnoxious p-median Problems
Get PDFThe obnoxious p-median problem consists of locating p facilities among a set of sites such that the sum distance from any demand to its nearest facility and the dispersion among facilities are maximized. In this paper, the multi-objective colliding bodies optimization algorithm (MOCBO) is utilized to obtain the trade-off curve of the obnoxious p-median problems. The performance of the developed optimization method is investigated for locating obnoxious facilities through two case studies to maximize the two conflicting objectives. The performance of the MOCBO algorithm is further compared with those of the MPSO and NSGA-II algorithms representative of the state of the art in the field of multi-objective optimization. In this study, the MOCBO algorithm showed suitable convergence performance and generalization abilities compared to the MPSO and NSGA-II algorithms
Cycle Bases of Graphs for the Analysis of Frames Structures Using Force Method
Get PDFThe formation of suitable cycle bases corresponding to sparse flexibility matrices for the force method of frame analysis has always been an interesting problem in structural mechanics. These cycle bases are needed for the formation of static bases for efficient force method of structural analysis. Similarly, such bases are required in the mesh analysis of other networks. This paper reviews methods for the cycle basis selection by utilizing different embeddings on higher dimensional topological spaces, and using the ideas and concept from this study, graph theory algorithms are developed for efficient computational algorithms for the formation of subminimal, and minimal cycle bases
Uncertainty's Effects Assessment and the Relevant Parameters on Soil-Pipe Interaction (SPI) System Responses Using Sobol Sensitivity Analysis
Get PDFBuried pipes play a crucial role in the transportation and distribution of various substances, such as energy, fluids, and waste, influencing daily life and industrial activities. The interaction between soil and pipes significantly affects the distribution of forces and stresses in the soil-structure systems. This study focuses on the soil-pipe interaction (SPI) system, employing the simplified Winkler model to represent SPI. The uncertainty in soil and pipe parameters is a major source of variability in the response model. To address this, five semi-empirical models for computing the soil reaction modulus are analyzed. A global sensitivity analysis, specifically the Sobol method, is employed to quantify the effects of uncertain input parameters on soil reaction modulus and pipe flexural strains. Results indicate that soil parameters, particularly Young modulus, have the most substantial impact on the soil reaction modulus, while pipe parameters exhibit negligible effects. The sensitivity analysis provides insights into the influential factors and their interactions. Moreover, a probabilistic analysis is conducted to assess the variability of soil reaction modulus and pipe displacement, revealing differences among semi-empirical models and soil types. This study contributes to identifying key parameters affecting the SPI system, allowing for better-informed decision-making in pipeline design and management. The findings emphasize the importance of considering uncertainties in soil and pipe properties for accurate predictions of soil-pipe system behavior
Historical Architecture and BIM Modelling: Between Representation of Reality and Conceptual Abstraction
Get PDFThe essay aims to explore the applications of BIM to design regarding historic buildings, which will become mandatory in Italy from 2025 for public works above €1 million. Despite the advantages in coordinated data management and information sharing among the actors involved in contracts, problems related to the geometric representation and semantic definition of the virtual entities that populate the models have been recognized by the scientific community. Critical issues that have emerged from the study of significant experiences can be traced back to the difficulty of adapting tools designed for the projects of new buildings to the characteristics of the cultural heritage. In particular, the complexity of proposing congruent categorisations and parameterisations seems related to only partial correspondence between historical building components, IFC classes and BIM software categories. These limitations often lead to the identification of contingent solutions and expedients, which solve only the problems of geometric representation. In contrast, the ability to adequately share information stored in databases, interoperable through the IFC format, is conveyed by an appropriate semantic description. Formal representation in the BIM environment effectively refers to standardized industrial production, reproducibility of building elements and, more generally, to the goals of globalisation. Thus, the proposed reflections aim to encourage a conscious use of these tools and to outline implementation perspectives useful to bring the digital environment closer to the concrete reality of historical architecture, unique and irreproducible in origin and transformation, often realized through artisanal processes and anchored to specific contexts in multiple aspects
Testing the Efficiency of a Heat Pump with Radiant Systems in Heating Mode
Get PDFThe paper deals with the experimental testing of the efficiency of the operation of an air/water heat pump in connection with three radiant systems in heating mode in an office building, which is part of the central laboratories of the Slovak university of Technology in Bratislava. The testing was aimed at verifying the manufacturer's theoretical claims about efficiency of the heat pump based on the COP and SCOP values according to EN 14511-1:2022 and EN 14825:2022. The testing period was from 7 Jan. 2024 until 15 Jan. 2024. The aim of the testing measurements was to evaluate the calculated value of SPF efficiency for individual days and for the testing period. During the measuring period, the wall radiant system consumed 188 kWh, the ceiling system 216 kWh, and the floor radiant system 196 kWh. The heat pump consumed 227 kWh of electricity. The calculated SPF value was 2.64