Approach to assessment of existing structures in the fib Model Code 2020

Abstract

Existing structures often no longer meet the demands formulated in contemporary design codes with respect to structural safety and serviceability. This occurs, for instance, if the loads on existing structures, like traffic loads on bridges, are larger than assumed in the original design. A second potential reason is that structures are subject to deterioration, like alkali–silica reaction within the concrete or corrosion of the reinforcement due to chloride attack or carbonation. A third possible reason is that in recent codes, additional criteria have been introduced based on new theories and/or negative experiences with older structures. The new fib Model Code for Concrete Structures 2020 will be valid both for the design of new structures and the assessment of existing structures. This paper shows how the design and assessment of concrete structures are integrated into this new code concept.

Assessment of existing structures in fib modelcode 2020: Solutions and examples

“…The new fib Model Code 2020 ( fib MC 2020) gives methods not only for the design of new concrete structures but also for the assessment of existing structures. As much as possible, it tried to use the same basic models for design and assessment 1 . It should, however, be emphasized that the behavioral models derived from tests in laboratories have been carried out on specimens made of new concrete, whereas structures to be assessed consist of concrete “with a history.” For a new standard concrete, the relations between compressive strength, tensile strength, E‐modulus, and other properties are reasonably unique.…”