Task Group 1.3
Calibration of Partial Safety Factors for the Assessment of Existing Bridges


Mission Statement/Objectives

Investigate how performance models (with a focus on semi-probabilistic approach) can be built with reference to physical models (parametric approach) and use potential information derived from inspection/monitoring strategies.

Scope & Limitation

As indicated in the JRC report of CEN/TC250/WG2, 2015), “The application of design-orientated methods to the assessment of existing structures often leads to a high degree of conservatism. This conservatism has severe economic, environment and socio-political consequences when it results in satisfactory structures being condemned as unsafe, thereby leading to an unnecessary investment of resources in replacement or retrofitting, with its associated dismantling. The approach to the assessment of an existing structure is in many respects different from that in designing new structures. The effects of the construction process and subsequent life of the structure, during which it may have undergone alteration, deterioration, misuse and other changes to its as-built (as designed) state, need to be taken into account. It is thus possible to obtain and gain more or less detailed information on a specific structure. This is one of the fundamental differences with respect to the methodology used for the design of new structures where uncertainties are dealt with by relying on information gained from experience.”

The partial safety approach considers the application of statistics and probability in the evaluation of the input data, the formulation of assessment criteria, and the determination of load and resistance factors. This approach allows easy calculations, while covering the variability in structural behaviour and loading. However, semi-probabilistic formats are not able to efficiency and correctly manipulate information obtained from measurements and inspections and their use for performance assessment of structures still represents a challenge. To overcome this limitation, a probabilistic approach will be considered to re-calibrate partial factors.

Expected Project Output
  • Identification of advanced approaches for calibration of partial safety factors for the assessment of existing bridges and possible implementation on case studies
  • SEI Journal special issue proposal
  • Organization of special sessions at some international conferences
  • Establish connection with JCSS and fib Task Group 3.1


Start Date: September 2018
Target Date of Completion: October 2022



  André Orcesi, France
  Vice Chair
  Salvatore Dibernardo, USA
  Jochen Köhler, Norway
  Marija Kušter Maric, Croatia
  Maria Pina Limongelli, Italy
  Heiki Lilja, Finland
  Nisrine Makhoul, Lebanon
  Jose Matos, Portugal
  Vazul Boros, Germany
  Marco Proverbio, Singapore
  Roman Lenner, South Africa