1,720,965 research outputs found
Applications of Remote Sensing
No full textThis book focuses on new perspectives and advanced theoretical and application research in remote sensing. It is concerned with the study of scientific problems of remote sensing and geodesy and related interdisciplinary sciences. It discusses some contemporary issues related to geodesy in engineering projects, which are critical components in civil construction and often require detailed management techniques and unique solutions to address failures and remedial measures. Chapters address such topics as mineral mapping, soft computing techniques, geodesign, marine geodesy, and much more. The book is a useful resource for surveyors, engineers, geodesists, and geophysicists
Comparison of Prediction Models for the Permeability of Granular Materials Using a Database
Full text linkThe hydraulic conductivity characteristics of the materials which comprise pavement structures are linked to in service performance. This paper briefly reviews a series of well-known models to predict hydraulic conductivity. An approach which makes use of the grading entropy coordinates is also studied. The database includes information on the gradation, hydraulic conductivity and porosity characteristics for over 150 gravel mixtures. Comparison of the studied models reveals that the ‘Kozeny-Carman’ model gives the best predictions when considering the entire database. The results of the regression analysis reveal that for granular mixtures comprising greater than 50% sand, the ‘Shepherd’ or ‘Hazen’ approaches may be preferred. However, for mixtures comprising less than with 50% sand, the ‘KozenyCarman’ and ‘grading entropy’ approaches are preferred
Failure Analysis
Full text linkThis book, Failure Analysis, covers a broadest sense failure to a narrowest sense one. One purpose of this book is to provide the reader with an overall picture of various failures and how to deal with them. Another purpose is to present the latest scientific advancements in this field. For instance, an innovative concept of true stresses is introduced and is shown to be necessary in dealing with a composite failure micromechanically
Geotechnical Engineering
Full text linkThis book discusses contemporary issues related to soil mechanics and foundation engineering in earthworks, which are critical components in construction projects and often require detailed management techniques and unique solutions to address failures and implement remedial measures. The geotechnical engineering community continues to improve the classical testing techniques for measuring critical properties of soils and rocks, including stress wave-based non-destructive testing methods as well as methods used to improve shallow and deep foundation design. To minimize failure during construction, contemporary issues and related data may reveal useful lessons to improve project management and minimize economic losses. This book focuses on these aspects using appropriate methods in a rather simple manner. It also touches upon many interesting topics in soil mechanics and modern geotechnical engineering practice such as geotechnical earthquake engineering, principals in foundation design, slope stability analysis, modeling in geomechanics, offshore geotechnics, and geotechnical engineering perspective in the preservation of historical buildings and archeological sites. A total of seven chapters are included in the book
Συμβολή σε μια ολιστική προσέγγιση της παθολογίας και της προστασίας υπόγειων μνημειακών κατασκευών εκτεθειμένων σε σεισμικό κίνδυνο. Εφαρμογή σε ορισμένα ελληνο-ρωμαϊκά μνημεία στην Αλεξάνδρεια της Αιγύπτου
No full textThe thesis presents an integrated and quite original holistic methodology for the pathology assessment and adequate retrofitting measures of underground monuments located in a region with unfavorable geographically, geotechnical, climatically and active seismic-tectonic regime. The methodology comprise (the archaeological impressions, oriented geotechnical, physiochemical, geochemical, geophysical surveys, construction materials studies and analysis and 2D-3D numerical static FE analysis and seismic analysis including the appropriate intervention retrofitting measures) for selected subterranean / underground monuments in Alexandria, Egypt i.e. the Catacombs of Kom El-Shoqafa, Amod El-Sawari or Pompey,s pillar with the Serapeum temple and ancient daughter library, El-Shatbi Necropolis and the Necropolis of Mustafa Kamil with its four excavated or rock- cut tombs. It presents a multidisciplinary approach for the study and retrofitting of these monuments taking in account that the region is belong to zone of moderate to high seismicity and it is know that at least two big tsunami disasters affecting Alexandria have been reported since ancient times. Modern underground structures (i.e. tunnels) are considered less vulnerable to seismic actions than above ground structures. However underground monuments like tombs, cemeteries and catacombs, present certain construction and geometrical particularities that make them quite vulnerable. The analysis of the static stability and the behavior of these complex monuments under strong seismic loading, together with other factors due to unfavorable site conditions, (high water level, aging and weathering, the area belongs to a zone of moderate to high seismicity), are the key factors for the efficient restoration and retrofitting of these underground monumental structures. In the present study, we present in a first phase a comprehensive geotechnical survey undertaken in the archaeological sites, comprising geophysical ambient noise measurements (microtremors), as well as field and short &long-term laboratory experiments and tests, in order to define the physical, mechanical and dynamic properties of the soils and soft rock materials where the underground monuments are excavated or dug. In the second stage, we present the main results of the detailed 2D, 3D static and seismic numerical analysis of these underground monumental structures (Catacombs). The seismic analysis is performed applying different seismic scenarios corresponding to the seismotectonic features of Alexandria. Advanced soil-rock elastoplastic modeling has been used through out the different phases of the numerical finite element analysis. In the third and last phase/task, we present the potential improvement of the global behavior of these underground monuments applying specific retrofitting measures especially to reduce the seismic risk on this kind of underground structures. The aim of the analysis (the pilot study) is fivefold: (a) to examine and compare weathering (processes, mechanisms, intensity, and rate) in these archaeological sites to represent one of the widespread environmental type in Egypt {semi-arid, marine, urban and industrial area (Alexandria), to define the pathology and the causes of deterioration and instability problems of these pilot monuments, (b) to assess and analysis of possible engineering geological problems at these archaeological sites and implications of rock structures in rock engineering, (c) to assess the pathology and proposed an integrated and quite original holistic methodology for the analysis and the retrofitting of the underground monuments in Alexandria as a pilot study, (d) to investigate the safety margins of the existing monuments, under their present conditions, against environmental (i.e. Rising water levels, aging, weathering and utter lack of preservation) and extreme seismic loads, (e) to assess the global risk due to several factors and to investigate the potential improvement of their global behavior applying specific retrofitting measures.Η παρούσα διατριβή παρουσιάζει την ολοκληρωμένη ανάλυση (γεωτεχνική, γεωχημική, γεωφυσικές έρευνες, αριθμητικές αναλύσεις –στατικές και δυναμικές– σε 2 και 3 διαστάσεις), καθώς και κατάλληλα μέτρα υποστήριξης και ενίσχυσης για επιλεγμένα υπόγεια μνημεία στην Αλεξάνδρεια της Αιγύπτου: για τις κατακόμβες του Kom El- Shoqafa, του Amod El-Sawari ή το στύλο της Πομπηίας, με το ναό του Serapeum και την αρχαία βιβλιοθήκη, τη νεκρόπολη του El-Shatbi και τη νεκρόπολη του Mustafa Kamil με τους τέσσερις εκσκαφέντες τάφους της. Οι σύγχρονες υπόγειες κατασκευές (σήραγγες) θεωρούνται λιγότερο τρωτές σε σεισμικές δράσεις σε σχέση με τις υπέργειες κατασκευές. Ωστόσο, τα υπόγεια μνημεία όπως οι τάφοι, τα κοιμητήρια και οι κατακόμβες παρουσιάζουν ορισμένες γεωμετρικές και κατασκευαστικές ιδιαιτερότητες που τις καθιστούν αρκετά τρωτές. Η ανάλυση της στατικής ευστάθειας και της συμπεριφοράς αυτών των σύνθετων μνημείων υπό ισχυρή σεισμική φόρτιση, μαζί με άλλους παράγοντες που οφείλονται σε δυσμενείς εδαφικές συνθήκες (υψηλός υπόγειος ορίζοντας, γήρανση και αποσάθρωση, η περιοχή ανήκει σε μια ζώνη μέτριας προς υψηλής σεισμικότητας), αποτελούν τους βασικούς παράγοντες για την αποτελεσματική αποκατάσταση και ενίσχυση αυτών των υπόγειων μνειμείων. Στην παρούσα μελέτη παρουσιάζουμε ως πρώτο στάδιο μια περιεκτική γεωτεχνική έρευνα που έγινε στους αρχαιολογικούς χώρους, αποτελούμενη από γεωφυσικές μετρήσεις μικροθορύβου, καθώς και δοκιμές πεδίου και εργαστηριακές δοκιμές –άμεσες και μακροπρόθεσμες– με στόχο τον προσδιορισμό των φυσικών, μηχανικών και δυναμικών ιδιοτήτων των εδαφών και μαλακών βράχων όπου έχουν εκσκαφεί τα μνημεία. Σε δεύτερο στάδιο παρουσιάζουμε τα κύρια αποτελέσματα της λεπτομερούς στατικής και δυναμικής αριθμητικής ανάλυσης σε 2 και 3 διαστάσεις που έγινε για τις υπόγειες αυτές κατασκευές (κατακόμβες). Η σεισμική ανάλυση γίνεται εφαρμόζοντας διάφορα σεισμικά σενάρια που αντιστοιχούν στα σεισμοτεκτονικά χαρακτηριστικά της Αλεξάνδρειας. Καθόλη τη διάρκεια των αριθμητικών αναλύσεων που έγιναν με πεπερασμένα στοιχεία, χρησιμοποιήθηκαν ανώτερα ελαστοπλαστικά μοντέλα εδάφους-βράχου. Στο τρίτο και τελευταίο στάδιο παρουσιάζουμε τις δυνατότητες βελτίωσης της συνολικής συμπεριφοράς αυτών των υπόγειων μνημείων, εφαρμόζοντας συγκεκριμένα μέτρα ενίσχυσης ειδικά για τη μείωση του σεισμικού κινδύνου σε τέτοιου είδους υπόγειες κατασκευές. Ο στόχος της ανάλυσης αυτής έχει τέσσερα σκέλη: Α) Εξέταση και σύγκριση της διάβρωσης (διαδικασίες, μηχανισμοί, ένταση και ρυθμός) σε αυτούς τους αρχαιολογικούς χώρους, σε μερικούς από τους πιο συνήθεις τύπους περιβάλλοντος στην Αίγυπτο (ημίξηρο, θαλάσσιο, αστικό και βιομηχανικό περιβάλλον – Αλεξάνδρεια), προσδιορισμός της παθολογίας και των αιτίων των προβλημάτων επιδείνωσης και αστάθειεας αυτών των μνημείων. Β) εκτίμηση και ανάλυση των ενδεχόμενων γεωτεχνικών προβλημάτων στους αρχαιολογικούς χώρους, καθώς και των επιπτώσεων στις κατασκευές στο βράχο από άποψης βραχομηχανικής. Γ) διερεύνηση των περιθωρίων ασφάλειας των υπαρχόντων μνημείων υπό τις παρούσες συνθήκες περιβάλλοντος (δηλ. υψηλή στάθμη νερού, γήρανση και αποσάθρωση) και υπό ακραίες σεισμικές φορτίσεις. Δ) εκτίμηση του συνολικού κινδύνου λόγω διαφόρων παραγόντων και διερεύνηση της ενδεχόμενης ενίσχυσης της συνολικής τους συμπεριφοράς με την εφαρμογή συγκεκριμένων μέτρων ενίσχυσης
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
Sustainable Construction and Building Materials
Full text link284 p.This book sheds light on recent advances in sustainable construction and building materials with special emphasis on the characterization of natural and composite hydraulic mortars, advanced concrete technology, green building materials, and application of nanotechnology to the improvement of the design of building materials. The book covers in detail the characterization of natural hydraulic lime mortars, a decade of research on self-healing concrete, biocomposite cement binding process and performance, development of sustainable building materials from agro-industrial wastes, applications of sugarcane biomass ash for developing sustainable construction materials, oil-contaminated sand: sources, properties, remediation, and engineering applications, oil shale ash addition effect in concrete to freezing/thawing, connection node design and performance optimization of girders, functionally graded concrete structures, cumulative tensile damage and consolidation effects on fracture properties of sandstone, key performance criteria influencing the selection of construction methods used for the fabrication of building components in the Middle East, fly ash as a resource material for the construction industry, degradation monitoring systems for a building information modeling maintenance approach, durability of composite-modified asphalt mixtures based on inherent and improved performance, and bitumen and its modifiers
NON-LINEAR STATIC ANALYSIS AND SEISMIC PERFORMANCE OF MODERN ARCHITECTURAL HERITAGE IN EGYPT
No full textThe objective of this paper is the investigation of the behavior of historic masonry structures subjected to static and seismic forces and the formulation of numerical models for use in structural analysis. The case study presented herein regards the seismic analysis of El-Sakakini palace (1892 AC) in Cairo, Egypt (damaged by the earthquakes occurred in 1992 and 1995). Firstly, we collected all data regarding the site, the geometry of manufact, the characteristics of materials of construction, the structure and the soil medium, etc. The paper presents the next part which includes the investigation of the static and seismic performance of these structures according to statistical data from recent earthquakes and finally the development of an analytical model of describing their performance. An analytical, plasticity-based Model is presented for the inelastic analysis of traditional masonry structures. The proposed Model is applied to the analysis of the El-Sakakini palace in Cairo. A non-linear model is developed, aiming to capturing the key in elastic mechanisms. The analytical model is implemented in the finite element code Autodesk® Robot™ Structural Analysis Professional and validated against experimental results. The results obtained suggest that for such structures non-linear static analysis provides a reasonable prediction of damage at the base of the palace, but is not however suitable for predicting the overall damage along the palace‘s entire height. The conclusive aim of the project is then to develop guidelines for the evaluation of the static and seismic vulnerability of historic masonry palaces. Ultimately, the analysis presents the optimal structural interventions to remedy the existing damage, also to prevent the formation of the same mechanisms under the action of future earthquake
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