In this paper, a
rehabilitation project of two box girder bridges is described. The aim of the
project was to
increase the load capacity of the bridges and, simultaneously,
to ensure their durability by filling the cracks and repairing defects. The
load capacity was increased by
strengthening the bridges by external tendons, the
criteria for choosing the tendon forces being to prevent further cracking and
growth of the midspan deflection. The analysis of the structure and the
construction is described, and the costs of the
rehabilitation is compared to
the costs of replacing the old bridges by new ones. The conclusion is made that
the criteria used resulted to larger prestress forces than were necessary only
for satisfying the requirement for the bending capacity. However, the chosen
solution is found more economical than building new bridges.