Assessment of load carrying capacity of damaged concrete
structures
PhD student Søren Gustenhoff Hansen
Department of Technology and Innovation, University of Southern Denmark
An increasing number of concrete bridges in Denmark as well as in many other countries are damaged due
to the lack of maintenance, poor concrete mixture or expected as well as unexpected deterioration. One of
the major challenges is the deterioration caused by Alkali Silica Reactions (ASR). ASR is a chemical reaction
between reactive types of concrete aggregate, water and alkali from e.g. the cement or de-icing salt. The
reaction induces an expansion in the concrete, and if the internal forces from the expansion exceed the
tensile strength of the cement paste, cracks will occur – known as ASR deteriorations.
Worldwide, many severe damages of
concrete bridges due to ASR have been
reported. Furthermore, it is expected
that a great number of existing and
currently well-functioning concrete
bridges have the risk to develop
damages due to ASR under the right
conditions/circumstances. The Danish
Road Directorate has estimated that
app. 600 Danish bridges have the risk
to develop ASR damages in the near Figure 1 – ASR deterioration in a bridge deck impregnated with
fluorescent epoxy
future.
To decide the right future for a damaged bridge the engineers must be able to conduct a reliable
assessment of the residual load carrying capacity of the structure. Unfortunately, the theories and models
for capacity calculations prescribed in the national standards and codes cannot be used. They are mainly
developed as (conservative) design tools for new structures and not intended for assessment of damaged
structures. As a consequence, the engineers are in many situations left with rough estimates on the residual
load carrying capacity.
The purpose of this research project is to develop a practicable method to assess the residual shear
capacity for bridge structures.
The objective is:
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To conduct experiments with exiting bridge structures, suffering ASR deterioration, to
create experimental documentation for shear capacity.
To conduct laboratory accelerated ASR expansion in (small-scale) bridge decks to create
the experimental documentation of the expansion progression.
To conduct laboratory accelerated ASR expansion in (full-scale) bridge decks to create the
experimental documentation of the expansion progression and associated shear capacity.
To develop a practicable method to assess the residual shear capacity for bridge structures.