Abstract

In the Eurocodes, the notion of reliability is presented and expressed in terms of the target failure probability. The three reliability classes (RC1, RC2 and RC3) are based on assumed consequences of failure and exposure of construction works to potential hazards, their levels of safety and probability of failure are represented by the reliability index β. The normal (most current) situation in the ultimate limit state is associated with RC2 reliability class, which leads to partial safety factors associated to a failure probability of 5 × 10⁻⁵ (reliability index β = 3.89) over a 50-year reference period. Certain exceptional structures are associated to very high stakes: because their failure would cause such unacceptable consequences, these may in turn require a lower failure probability (typically ranging from 10⁻⁷ to 10⁻¹² per 50 years) during their design working lifespan. For these more restrictive situations (reliability class higher than RC3), this article exemplifies a simplified method for calibrating partial safety factors on materials and actions, as well as model uncertainties, according to Eurocodes. A discussion is offered at the end of this article to consider the combined use of this simplified method with other measures to ensure the required reliability levels for concrete structures.

摘要

在欧洲规范中，可靠性的概念以目标故障概率的形式提出和表达。三个可靠性等级（RC1、RC2 和 RC3）基于假设的故障后果和建筑工程对潜在危险的暴露，其安全等级和故障概率由可靠性指数β表示。最终极限状态下的正常（当前）情况与 RC2 可靠性等级相关，这导致部分安全系数与 5 × 10 ^-5的故障概率相关（可靠性指数β = 3.89) 在 50 年的参考期内。某些特殊结构与非常高的风险相关：因为它们的故障会导致这种不可接受的后果，这些可能反过来在其设计工作寿命期间需要较低的故障概率（通常在每 50 年10 ^-7到 10 ^{-12的范围内）。}对于这些更具限制性的情况（可靠性等级高于 RC3），本文举例说明了根据欧洲规范校准材料和动作的部分安全系数以及模型不确定性的简化方法。本文末尾提供了讨论，以考虑将这种简化方法与其他措施结合使用，以确保混凝土结构所需的可靠性水平。