Structural assessment of existing concrete buildings

✍ Scribed by Roberto Laranja; Jorge de Brito

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 168 KB
• Volume: 5
• Category: Article
• ISSN: 1365-0556
• DOI: 10.1002/pse.145

✦ Synopsis

Abstract

An approach to the general issue of existing concrete structures safety analysis is presented, referring to the most relevant uncertainties in the process of structural assessment and the various ways of characterizing them. The structural reliability and reliability index concepts and a procedure to measure them probabilistically are presented, as well as the basic problem of structural reliability and a semi‐probabilistic approach to safety compliance.

The importance of characterizing the strength properties of structural materials is discussed, and the main related aspects are pointed out. Methods prescribed in some standards and recommendations are presented, emphasizing those suitable for safety analysis of existing structures. The importance of a priori data, the sources normally used in data acquisition and of
the inspection and tests planning stages is stressed. The number of tests (sample dimension) needed to infer and statistically validate results is discussed.

The importance of characterizing probabilistically actions and effects is stressed. The code criteria for their quantification are presented and the types of probabilistic distribution and variability inherent to each action type are briefly described. Some methods for their quantification in existing structures are pointed out. Special importance is given to the quantification of variable actions, owing to the high associated uncertainties, especially seismic action, in the process of structural safety assessment. Ways of reducing their nominal values or the respective safety factors, depending on the degree of uncertainty involved, namely due to the reduction of the existing structure's expected service life, are pointed out.

The probabilistic methodologies developed for structures safety analysis, based on the reliability classical techniques, namely the second moment methods, of First and second order, and those based on the numerical simulation (Monte Carlo) techniques, are discussed, emphasizing the difficulty in its application to case studies of the assessment of existing structures. Copyright © 2003 John Wiley & Sons, Ltd.