Reliability-Based Assessment of Concrete Strength in Existing Structures

ABOUT THE INTERNATIONAL CONCRETE ABSTRACTS PORTAL

  • The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.

International Concrete Abstracts Portal

  


Title: Reliability-Based Assessment of Concrete Strength in Existing Structures

Author(s): F. M. Bartlett

Publication: Special Publication

Volume: 198

Issue:

Appears on pages(s): 85-102

Keywords: compressive strength; concrete cores; evaluation; in-place strength; load; resistance

Date: 3/1/2001

Abstract:
In 1988, the collapse of a supermarket roof in Burnaby, Canada, highlighted the need to distinguish between the specified strength and the actual strength of a material when evaluating existing structures. It is unsafe to calculate resistances using the actual strength instead of the specified strength in conven-tional resistance equations with customary resistance factors. This is the rationale behind current criteria for the evaluation of existing bridges in Canada, that require in-place strength data to be converted to equivalent specified strengths. In this paper, the statistical relationship between the specified strength and the actual in-place strength of concrete is examined. A method is summarized which enables concrete core compression strength data to be converted to an equivalent specified strength for structural assessment purposes. The method is illustrated by a case study involving 1200 40-year-old precast stringer bridges in Alberta, Canada.