Fatigue of reinforced concrete structural element

The objective is to investigate the fatigue behaviour of structural elements in reinforced concrete of bridges and wind turbines including novel cementitious materials like Ultra-High Performance Fibre Reinforced Concrete (UHPFRC). Relevant fatigue prone structural elements usually are bridge deck slabs and short span bridge elements as well as foundations and towers of wind turbines. Novel methods for the design of new structures and for the examination of existing structures and their elements shall be developed. The research findings will provide the necessary knowledge for establishing a novel engineering approach based on monitoring by inspections or continuous measurements cross-validating fatigue damage model for concrete and UHPFRC including stochastic aspects. This will allow determining the fatigue safety in a reliable way optimising thus cost of transportation and energy production infrastructures.

Host Institution

EPFL – Swiss Federal Institute of Technology Lausanne, Switzerland

ESR5

Bartłomiej Sawicki

Local academic supervisor

Prof. Dr. Eugen Brühwiler (EPFL)
eugen.bruehwiler(at)epfl.ch
Tel: +41 21 693 2882 

Industrial co-supervisor

Sandrine Chanut (EIFFAGE)
sandrine.chanut(at)eiffage.com
Tel: +33 (0)1 71 59 17 98

Dr. Ziad Hajar (EIFFAGE)
ziad.hajar@eiffage.com
Tel: +33 (0)1 71 59 17 97

PhD enrolment

EPFL – Swiss Federal Institute of Technology Lausanne, Switzerland
PhD Director: Prof. Dr. Eugen Brühwiler

Start date: 1st January 2017
Duration: 36 months

Synopsis

The service duration of structures like reinforced concrete bridges and wind turbines depends on the fatigue behaviour and fatigue strength of structural components. In order to realistically evaluate the fatigue safety of these structures by engineering methods, precise data regarding the fatigue action effect (characteristics, amplitude) due to traffic loading and wind respectively are needed. Those data can be obtained by long term monitoring of existing structures. In addition, knowledge about the fatigue behaviour of reinforced concrete needs to be improved and novel engineering methods for realistic fatigue safety verification shall be proposed. Novel cementitious materials like Ultra-High Performance Fibre Reinforced cement-based Composites (UHPFRC) shall be investigated to explore ways to build the next generation bridges and wind turbines as well as to improve existing structures.

Objectives

The general objective is to investigate the fatigue behaviour and fatigue strength of structural elements in reinforced concrete of fatigue prone elements and components of bridges and wind turbines including novel cementitious materials like Ultra-High Performance Fibre Reinforced cement-based Composites (UHPFRC) and to implement the findings by means of a methodology to verify the fatigue safety of bridges and wind turbine towers and foundations.
The project has the following objectives:

  • Analysis and interpretation of data from long term monitoring (continuous in-situ measurements) of one bridge and tower of a wind turbine to deduce a model describing the fatigue action effect.
  • Experimental investigation of the fatigue behaviour of reinforced concrete and/or UHPFRC.
  • Validation of the findings by means of case studies.

Tasks and methodology

  • Thorough literature review to identify and define an experimental campaign to investigate the fatigue behaviour of reinforced concrete and/or UHPFRC (which is a novel cementitious building material having the potential to build structures with higher performance in terms of fatigue and life-cycle costs)
  • Based on the results of the experimental campaign and monitoring data, develop analytical engineering methods for the determination of fatigue strength (and possibly the fatigue endurance limit)
  • Develop a novel fatigue damage model for concrete and UHPFRC including stochastic aspects
  • Validate the concrete fatigue damage model in view of its implementation and application for the fatigue safety verification within the design and examination of fatigue relevant structural elements in reinforced concrete and UHPFRC

Results

  • Novel and validated engineering methods for the fatigue design of new structures and for the fatigue examination of existing structures (bridges and components of wind turbines) based on data from monitoring
  • 3 (accepted) peer-reviewed papers
  • Successfully defended PhD thesis

Dissemination

  • Three peer reviewed papers
  • Two presentations at national/international conferences
  • Presentations at workshops and for potential end-users

Secondments

  • AAU (Aalborg, Denmark)
    August & September 2017
    Establish basis and develop a methodology for stochastic modelling of physical and model uncertainties for fatigue of concrete using a probabilistic approach
  • IFSTTAR (Nantes, France)
    December 2017 & January 2018
    Physical characterisation and modelling of fatigue action and fatigue action effect using data from bridge monitoring
  • EIFFAGE (Vélizy-Villacoublay, France)
    June 2018
    Design and construction of structures in UHPFRC

Research field

Structural engineering, cement-based materials, fatigue of reinforced concrete and UHPFRC, structural health monitoring

Keywords

Monitoring, fatigue, UHPFRC, reinforced concrete, bridges and wind turbine towers

Key publications

There are no single key publications but a series of easy to access papers on:

  • the fatigue behaviour and fatigue strength of reinforced concrete as well as UHPFRC
  • structural health monitoring
  • fatigue and reliability of structures like bridges and wind turbines