Adaptation Of Urban Riveted Steel Structures - Development Of An Assessment And Strengthening...

Universities and Institutes of France
January 31, 2023
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  • Organisation/Company: Université Gustave Eiffel
  • Research Field: Engineering › Civil engineering
  • Researcher Profile: First Stage Researcher (R1) Recognised Researcher (R2) Established Researcher (R3) Leading Researcher (R4)
  • Application Deadline: 31/01/2023 00:00 - Europe/Athens
  • Location: France › bouguenais
  • Type Of Contract: Temporary
  • Job Status: Full-time
  • Offer Starting Date: 01/11/2023
  • A significant part of the urban structures and infrastructures heritage is made up of riveted metal structures. However, the evolution of urban uses and needs may imply a replacement of these structures or their adaptation. However, when considering their adaptation or the reuse of certain metal parts, the design offices encounter difficulties during the assessment of their degree of damage, or during the reinforcement phases. These difficulties are exacerbated in the case of old structures that are of acute heritage interest.

    Civil engineering structures and infrastructures are subjected to static and dynamic stresses (mechanical and thermal loads) responsible for their deterioration as well as to aggressive environments favoring the development of corrosion. These two phenomena, combined or not, can accelerate ageing and even lead to the destruction of the constituent elements. Structural elements under load are the most threatened by this damage. In the case of riveted structures, it is still difficult to assess the degree of damage to riveted connections. In this context, investigations on structural assessment tools are necessary in order to propose a relevant method for assessing the degree of damage, which could also allow monitoring of the structural health during the life of the structure or structural element.

    Old structures were designed and built according to different codes and techniques than today. Their understanding is often incomplete. This leads, for precautionary reasons, to repair or reinforcement measures which can be invasive from a heritage point of view and heavy on the budget. An inventory of existing methods is necessary, as well as a proposal for a selection methodology. The latter must be based on experimental investigations to evaluate their effectiveness.

    In this context, this thesis aims to propose and validate a methodology including an evaluation (inspection) and monitoring approach of riveted metallic structures, and a selection approach of the repair/strengthening method(s) of metallic structures assembled by riveting. The techniques for assessing the health of these structures to detect structural failure will be carried out at two scales, global and local. An analysis and an interpretation of the results will be made to propose in a second step a method of repair and/or reinforcement of these structures allowing to adapt them to new constraints, to reuse them, but also to make them more resilient towards climate change.

    Nowadays, the metal trusses with rectilinear crossbeams from the second half of the 19th century constitute a family of structures that is still very much represented, with common assembly typologies. A good understanding of the functioning of the connections and supports is essential for the evaluation of their overall bearing capacity. In the absence of more detailed analysis, the stiffness of the connections is modelled in an idealized way: most of the connections are assumed to be hinged to favor normal forces in the structural elements, while the supports are assumed to be perfectly slippery so that the lower members of the trusses function well in tension. The strength check of the connections is neglected. This leads to an approximate, not necessarily conservative, assessment of the structural behavior and to the recommendation of perhaps unnecessary or inappropriate interventions.

    In the first year, a bibliographical study will be carried out on the subject. Particular attention will be paid to the identification of the main pathologies and to the existing or possible non-destructive testing or inspection methods to assess their degree of damage. These methods will be implemented on a series of riveted lattice girders in order to assess their relevance, reliability and ease of implementation. The vibratory method will be investigated in particular in continuation of the work of H. Franz (Thesis in progress at SMC Laboratory). On the basis of these results, a first selection of methods will be made.

    The second year will aim to damage all or part of the lattice girders studied in order to study the capacity of the selected methods to assess their degree of damage. For example, measurements will be carried out after some rivets have been loosened and replaced by bolts, or prestressed bolts with different tightening levels. This will enable the most appropriate inspection or structural assessment method to be defined and its implementation parameters to be reproduced on site. A survey of repair/reinforcement methods will also be carried out. Among these methods, recent solutions involving the use of structural bonding will be studied in particular in order to propose several repair/reinforcement methodologies.

    The third year will be devoted to the on-site implementation of the defined structural assessment methodology, as well as to the performance of several experimental investigations aimed at validating the proposed reinforcement/repair solutions. In the end, an approach for the choice of the reinforcement/repair strategy will be determined.

    The thesis will take place in the Laboratory of Metallic and Cable Structures of the Gustave Eiffel University in France. This laboratory has strong competences on the subject, with an experienced team of supervisors and experimental means adapted to the subject of the thesis (instrumentation, mechanical testing means, competences on repair/reinforcement techniques, knowledge on riveting). This project will allow the PhD student to acquire knowledge in the field of metallic structures and works essential to the energy transition, to contribute to the circular economy by proposing technical and technological solutions allowing to reduce the costs of maintenance and repairs of riveted structures. The candidate will develop these skills in numerical analysis and in conducting tests in the laboratory and on site.

    Funding category: Financement de l'Union européenne

    MSCA-Cofund

    PHD Country: France

    Offer Requirements Specific Requirements

    cf.

    https: // euraxess.ec.europa.eu/jobs/847761

    Contact Information
  • Organisation/Company: Université Gustave Eiffel
  • Organisation Type: Public Research Institution
  • Website: https: // www. univ-gustave-eiffel.fr/
  • Country: France
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