Graduation of Kamal Laghmouchi

22 januari 2021 11:00 - Locatie: Online - Door: Webredactie | Zet in mijn agenda

Reliability updating of existing quay walls based on effects of past performance

  • Professor of graduation: Dr. ir. J.G. (Jarit) de Gijt
  • Supervisors graduation: Dr. ir. A.A. Roubos (TU Delft), dr. ir. T. Schweckendiek (TU Delft), dr. ir. Y. Yang (TU Delft), dr. ir. O.M. (Otto) Heeres (Arcadis), Prof. ir. A.C.W.M. Vrouwenvelder (TNO)

Background

Many quay walls approach the end of their intended design life and worldwide many harbour programs will be started for the assessment and renovation of these quay walls. It is relevant to properly assess the reliability of these structures in the time domain to make a sound decision about extending the structure’s lifetime or executing proportional measures such as the construction of a new quay wall. In recent studies, it appears that the actual reliability of geotechnical structures such as quay walls can be determined based on different aspects. Despite the degradation due to for instance corrosion, service life can be extended for many well-functioning quays. This is because the time-independent uncertainty related to the effective soil parameters, which can be described with stochastic variables, positively influences this type of structure. Depending on the location, the effect of time-dependent uncertainties is smaller in the case of quay walls than in the case of multi-storey buildings and bridges. Hence, the reliability of quay walls can be updated by means of information of past performance. The national guidelines for design are based on the Eurocode 0 (basis of structural design). The reliability differentiation in this European standard is based on the behaviour of buildings and bridges which are governed by time-dependent uncertainties. The current Dutch practical guidelines (NPR), which are still in development, do not yet include the effects of past performance.

Abstract

In this research, the effect(s) of past performance on the reliability of a quay wall were studied by means of the Equivalent Planes method. The Equivalent Planes method, in this research also referred to as Hohenbichler-Rackwitz method, has already been applied in the field of flood defences and appears to be an efficient method. One frequently occurring failure mechanism was studied in this research. The Equivalent Planes method repeatedly formulates a limit state expression for several (spatial or temporal) components into a single simplified expression. This research used the Equivalent Planes method to illustrate the effect(s) of including information of survived years, degradation and other time-related effects on the reliability of quay walls. Correspondingly, the behaviour of the sensitivity factors, representing the relative influence of the governing random variables, were visualised. By means of the newly obtained information, partial safety factors can be updated with the semi-probabilistic level I method. 

Link to MS Teams Meeting (Please mute your self as soon as you join the meeting)