Konstantinos E. Mixios

selected publications

1. 5ETAM 2022

   Δυναμική ανάλυση συστήματος γέφυρας-αμαξοστοιχίας με την τεχνική της συν-προσομοίωσης (GR)

   5ο Πανελλήνιο Συνέδριο Αντισεισμικής Μηχανικής και Τεχνικής Σεισμολογίας Sep 2022

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   Στην παρούσα εργασία εφαρμόζεται η τεχνική της συν-προσομοίωσης στο σύστημα γέφυρας-αμαξοστοιχίας. Το υποσύστημα της αμαξοστοιχίας επιλύεται με τη χρήση ενός κώδικα C++, ο οποίος περιλαμβάνει μια μαθηματική διατύπωση που περιγράφει τους αμφίπλευρους και μονόπλευρους περιορισμούς με την χρήση διαφορικών εξισώσεων (ODEs). Η αμαξοστοιχία επιλύεται με τη χρήση της δυναμικής ανάλυσης πολλαπλών σωμάτων (Μultibody dynamics), ενώ το σύστημα της γέφυρας μοντελοποιείται και επιλύεται με τη χρήση του OpenSeesPy. H σύζευξη των δύο αυτών υποσυστημάτων γίνεται με την χρήση ενός κώδικα ενορχήστρωσης (orchestrator) αναπτυγμένο στην γλώσσα προγραμματισμού Python. Πραγματοποιείται η αλληλεπίδραση στο πεδίο του χρόνου, λαμβάνοντας υπόψη την σωστή μεταφορά των δυνάμεων, της ταχύτητας και των μετακινήσεων μεταξύ των υποσυστημάτων. Ο τρόπος επικοινωνίας και ανταλλαγής των πληροφοριών μεταξύ των δύο υποσυστημάτων γίνεται στο πλαίσιο του προτύπου FMI (Functional Mock-up Interface).

2. Master Thesis

   Parametric analysis of monotonic and cyclic behaviour of soil-pipe interaction with finite element method

   Konstantinos, Mixios E.

   Master Thesis, Aristotle University of Thessaloniki Jan 2020

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   The analyses of the soil-structure interaction phenomenon can be invoked to improve the planning and design of buried pipelines, to guide monitoring, and to reduce the risk of damage and failure. In this thesis, a parametric study was conducted to investigate the mechanical behavior of the soil-pipe interaction utilizing the Finite Element program OpenSees. Raw data from small scale laboratory tests, which were conducted at the University of Toronto (Prof. Oh-Sung Kwon, Tryfonos Kyriakos, PhD student), were used to develop and calibrate numerical models. The numerical simulations are divided in two separate series: in the first, the pipe diameter is 50mm; in the second series, the pipe diameter is 100mm. Loose sand soil properties were used. The main parameter that changes in the numerical models that can be easily noticed is the dimensionless buried depth of the pipe. To be more specific, for the 50mm diameter pipe, 5 models with different dimensionless buried depth were developed, and for the 100mm diameter pipe, 3 models with different dimensionless buried depth were developed. All the above-mentioned models were imposed in monotonic loading, with respect to the loading protocols of the laboratory tests. The numerical models were calibrated to fit the experimental results utilizing all the necessary data

3. SECED 2019

   A Comparative Experimental Study of Strengthened Columns using Steel Reinforced Grout (SRG) Jacketing

   SECED 2019 Conference - Earthquake Risk and Engineering towards a Resilient World Sep 2019

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   This paper presents the results of a recent experimental investigation of short reinforced concrete column-type specimens, externally confined with Steel Reinforced Grout (SRG) jackets. Three groups of specimens were casted and tested under monotonic uniaxial compression. Each group comprised three different specimens, with a geometry of 200×200×380 mm, corresponding to a 2/3 scale of a 300×300 mm column. Parameters of investigation were the transverse steel reinforcement (i.e. no reinforcement, 100 mm spacing and 200 mm stirrup spacing) and the number of SRG layers (i.e. one or two). The geometry and the materials were selected to be similar to experimental setups found in literature. Thus, a comparison between SRG, Fiber Reinforced Polymer (FRP) and Textile Reinforced Mortar (TRM) jacketing for confinement was possible. Experimental evidence demonstrated that all alternative jacketing systems were able to increase both strength and deformation capacity of the specimens.