Probabilistic Evaluations of Prescribed Safety Margins in Eurocode 7 for Spread Foundations

Abstract

According to the design code Eurocode 7, analysis procedures require reaching a prescribed safety margin, based on the conditions of levelling design action and design resistance. Such semi-probabilistic procedures do not result in a consistent equivalent value of the Overall Factor of Safety (OFS), neither in individual analysis nor in different tasks in geotechnical engineering. Furthermore, the implementation of different calculation approaches in Eurocode 7 also does not guarantee an equal probability of the occurrence of a relevant limit state. A comparative analysis is conducted for an example of a centrically loaded spread foundation on homogenous, isotropic, and coarse-grained soil, according to procedures in Eurocode 7, Design Approach 3. An algorithm is developed to estimate failure probability, taking into consideration the relevant statistical characteristics of each calculation parameter. A significant influence of the statistical characteristics of the relevant sample is emphasized. The degree of required modification of the equivalent Overdesign Factor (ODF) and the Overall Factor of Safety (OFS), based on the criterion of the required reliability index β and failure probability pf , is quantified.

Reliability of Municipal Solid Waste Landfills within the Eurocode Framework

“…According to [20,21], for geotechnical structures analyzed according to EC7, there is no clear correlation between measures of stability and reliability. In practice, this implies that a structure may satisfy the criteria for stability but fail to meet the criteria for reliability, or vice versa.…”

Probabilistic Analysis of Shallow Foundations on c-φ Soils Using 2nd Order Response Surface Methods

“…The Hasofer-Lind reliability index β HL , the corresponding design points (φ*, c*, γ*, q*) for different values of random applied pressure varying from small values up to ultimate applied pressure q ult , are presented using Eq. (7).…”

“…Probabilistic investigations of shallow foundations on both cohesive soils (e.g., [1][2][3]) and cohesionless soils (e.g., [4,5]) including granular materials (e.g., [6,7]) have been performed by different researchers. Moreover, safety assessments of shallow foundations resting on c-φ soils have been carried out by various authors (e.g., [8][9][10] just to name a few).…”