Verification of load factors for concrete components by reliability and optimization analysis: Background documents for implementing Eurocodes

✍ Scribed by Milan Holický; Jana Marková

• Book ID: 105360988
• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 214 KB
• Volume: 2
• Category: Article
• ISSN: 1365-0556
• DOI: 10.1002/pse.55

✦ Synopsis

Abstract

The European standards for the design of construction works, the Structural Eurocodes, are presently at a stage of transformation from their ENV status to operational EN documents. Available drafts and other working materials clearly indicate that the decision concerning alternative procedures and reliability elements will remain in the competency of national responsible authorities. One of the most important issues is the determination of the partial safety factors for permanent and variable loads. Simple examples of reinforced concrete components, considered in the present study, indicate that a structure designed on the basis of the recommended values for these safety factors in the latest drafts of the proposed EN standards will be of adequate reliability. Moreover, in some cases reduction of the safety factors may lead to unsatisfactory reliability. Thus it appears that a possible downward modification of recommended safety factors and other reliability elements should be supported by comprehensive studies, and preferably limited to those cases which are linked to national (regional) conditions, e.g. to climatic actions and their combinations. This recommendation is supported by probabilistic optimization, taking the total expected cost as an objective function and the partial safety factors for permanent and imposed loads as decisive parameters. The total cost further depends on the malfunction cost to the marginal costs for permanent and imposed loads. It appears that the optimum values of the partial safety factors may be expected to be very close to the values recommended in the draft of EN 1990.