1,721,106 research outputs found
On the Use of Steel Exoskeletons for Seismic Retrofit of Existing RC Buildings: A Case Study
No full textSince the ‘80s the use of steel external additive structures is considered one of the most suitable techniques for seismic retrofit of existing RC structures with low dissipative capacity. This structural typology, called exoskeleton, made its first appearance in 2000s in the Japanese and American codes dealing with structural rehabilitation issues. Nowadays, exoskeletons can be implemented without interrupting the building use and they are also used for the integrated retrofit of the building systems. In the present work, after the typological classification of steel exoskeletons in families and the definition of their key project parameters, the application of these systems to the case study of the primary school P. Santini in Loro Piceno, a district of Macerata, has been shown for illustrative purpose
Classification of european building stock in technological and typological classes
No full textNowadays it is known that the European building stock is energy-intensive and insecure: constructions need interventions both to solve performance and structural deficiencies and to reduce the current unsustainable energy waste. An intelligent retrofit for existing structures should offer an intervention integrating all the different performance requirements, such as structural safety, energy efficiency and architectural quality together with optimization of construction processes and costs. To this purpose, it is, therefore, essential to improve knowledge on the composition of the existing building stock. In this work, by analysing and processing the quantitative and qualitative data available from different countries, it has been possible to define an accurate building technologies map showing both the seismic-resistant structures and the envelope systems, the latter to evaluate also the environmental behaviour of buildings in terms of Life Cycle Assessment (LCA) and energetic consumptions. Afterwards, the seismic and climatic characteristics of all the European countries have been considered, so leading towards the definition of zones with different combined hazard conditions. Through all the possible combinations between these seismic and climatic zones, it has been conceived a hazard matrix, where different case studies can be placed aiming at showing potentialities of different retrofit solutions from seismic and energy viewpoints. The investigation of these case studies, which will be analysed in a companion paper, allows to cover all the possible constructions and hazards detected at European level, so to implement an analysis method to be used in every Countries in Europe
Scan-To-Bim Procedure for an Old Industrial Plant
No full textThe work presents an efficient solution, based on integrating different data sources, for the digitization and modelling of an old structure with the HBIM methodology. It deals with survey issues, focusing on the various design approaches between parametric and not-parametric architectural elements. A procedural pipeline is formalized for data acquisition, processing, and generating a complete model for a disused industrial plant, formerly used for tobacco processing and located in the city of Battipaglia, Italy. The most difficult challenge is to obtain parametric objects of complex geometries. The results obtained corroborate with the robustness and accuracy of the proposed strategy
BIM reverse modelling process for the documentation of Villa Rufolo in Ravello
Full text linkThe primary purpose of this work is the definition of a protocol for the accuracy check in a BIM process, from digital survey to three-dimensional reconstruction. The development of a BIM model for existing buildings is, in fact, basically a reverse engineering operation and, as far as the reproduction of the geometries is concerned, a coded pipeline for the accuracy control is still missing. The result of the modelling process is a local volumetric entity where the object of interest is decomposed into portions and each element is described through a finite number of parameters. This model then becomes the repository of all the systematised data collected for Villa Rufolo, a landmark of the Amalfi Coast, to define an environment that can offer a valid support to decision-making processes for future restorations
AN EFFECTIVE APPROACH FOR POINT CLOUD DENOISING IN INTEGRATED SURVEYS
No full textOutliers and noise in point cloud data are unavoidable due to intrinsic and/or extrinsic survey factors. Significant errors may result from false geometry produced by a collection of anomalies, compounded by sparse structure, irregular densities, and lack of geometric cohesion typical of point clouds nature. Thus, filtering techniques on raw data are required to produce accurate point clouds suitable for further processing. This objective is pursued in the following study through a comparative analysis between two registered clouds, one obtained from TLS, used as reference dataset and the other – to be filtered – from SLAM system. Four steps make up the workflow: analysing the comparison models’ geometric attributes, specifically surface density and roughness; constructing statistical tolerance limits for the TLS cloud’s roughness distribution; cleaning the SLAM cloud; assessing the filtering outcomes. Our efforts to effectively remove and mitigate noise, while preserving the original detail features of the object surface, have been driven by the detailed articulation of point cloud denoising approaches that have been introduced in recent years. However, in this wide context, our goal is not to provide a review or to explore the details of the various methods; rather, we want to offer a simple yet efficient method for obtaining an integrated model with a uniform noise level. This can be especially useful when the data from the survey will later be used in source-based modelling
Methodologies for assessing the quality of 3D models obtained using close-range photogrammetry
Full text linkAlthough reality-based models are widely used to describe the geometric surfaces of an entity in a digital space, a systematic and universally recognised treatment of issues such as accuracy is lacking. The topic is certainly complex as this analysis should involve not only shape approximation but also other attributes (e.g., colour). Wanting to limit ourselves to geometry alone, this work proposes solutions for assessing the quality of photogrammetric models, differentiating them according to possible scenarios: sometimes, homologous models obtained using different techniques and technologies are available. In these cases, a comparison between digital reconstructions can serve to effectively quantify accuracy; more often, no terms of comparison are available, and one is forced to derive indicators from the same photogrammetric process to describe quality. We propose for this scenario a statistical analysis on the covariance matrix of the estimated coordinates for the tie points. The main goal is to provide a range of possible approaches to the conscious management of survey data
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
High Temperature Fatigue Behavior of Eutectic Al-Si-Alloys Used for Piston Production
No full textAbstractPistons of IC engines are typically subjected during operation to high cycle fatigue loading cycles at high temperatures (up to 350°C) in areas facing the combustion chamber. During operation the high temperature exposure results in a progressive loss of fatigue strength of the material at the weakest areas of the piston and may eventually results in a premature failure by crack initiation and propagation. The quantification of the temperature effect on fatigue strength inevitably require experimentation since such data are scarce.An extensive fatigue testing program of eutectic Al-Si alloys at room temperature and at several high temperatures (250°C, 300°C and 350°C) is reported. Specimens were extracted from piston crowns and tested in a rotating bending test machine. The resulting fatigue strength loss at 107 cycles is quantified by a staircase approach. The influence of the test temperature is investigated in terms of chemical composition, process route and of mechanisms of fracture observed in the broken specimens
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