Risk-based target reliability indices for quay walls

Abstract

Design codes and standards rely on generalised target reliability indices. It is unclear, however, whether these indices are applicable to the specific risk-profile of marine structures. In this study, target reliability indices for quay walls were derived from various risk acceptance criteria, such as economic optimisation, individual risk (IR), societal risk (SR), the life quality index (LQI) and the social and environmental repercussion index (SERI). Important stochastic design variables in quay wall design, such as retaining height, soil strength and material properties, are largely time-independent, whereas other design variables are time-dependent. The extent to which a reliability problem is time variant affects the present value of future failure costs and the associated reliability optimum. A method was therefore developed to determine the influence of time-independent variables on the development of failure probability over time. This method can also be used to evaluate target reliability indices of other civil and geotechnical structures. The target reliability indices obtained for quay walls depend on failure consequences and marginal costs of safety investments. The results were used to elaborate the reliability framework of ISO 2394, and associated reliability levels are proposed for various consequence classes. The insights acquired were used to evaluate the acceptable probability of failure for different types of quay walls.

Value of information of combinations of proof loading and pore pressure monitoring for flood defences

“…If the reliability of dikes is changing significantly in time, one also has to consider reinvestments. However, due to the dependence of slope stability reliability on time-independent ground-related uncertainty, slope stability of dikes (and other geotechnical structures, see e.g., Roubos et al (2018)) is typically rather time independent. Therefore, in an economic optimization one can estimate the annual target reliability by considering an infinite time horizon, such that the optimal level of protection b T , follows from the following minimization:…”

“…A reference period of 1 year is assumed, in line with common practice for flood defence structures. It should be noted that in some cases for geotechnical structures, the use of other reference periods might be more adequate (Roubos et al, 2018), and for instance the time factors provided in Diamantidis et al (2019) may be applied. The cost of the reference strategy without monitoring and proof loading is defined as c 0 : The Value of Information (VoI) of a strategy fp,m,dg can be computed by:…”

“…Consequently the future failure probability might be overestimated in cases with large knowledge uncertainty, most notably the case without uncertainty reduction. However, as the failure probabilities are relatively small, the overall effect is expected to be small as well (Klerk et al, 2018;Roubos et al, 2018).…”

Design and Construction Risks for a Shipping Port and Container Terminal: Case Study

“…(1) breakwater design (Koc 2009), (2) quay wall design (Roubos et al 2018), (3) land reclamation (Lendering et al 2015), and (4) dredging (Nebot et al 2017). When conducting a literature review on peer-reviewed research containing checklists that can be used in risk identification for construction projects, it appears that publications can be categorized as follows:…”

Reliability Evaluation in Construction Quality Based on Complex Vague Soft Expert Set Method

“…The units and parts of modules limiting reliability are used for the assessment of reliability. Alfred [18] developed a method to determine the influence of time-independent variables on the development of failure probability over time. This method can be also used to evaluate target reliability indices of other civil and geotechnical structures.…”