Przypadek wzmocnienia mostu przez zastosowanie zabiegów konstrukcyjnych i materiałowych

This paper presents a case study of a strengthening of a three-span road bridge made of precast WBS beams. Strengthening was required due to the road class change and consequently a significant increase of heavy traffic on the bridge. Hence, the super-structure (precast beams) had to be redesigned / strengthened to carry the load appropriate for Class B in accordance with PN-85/S-10030, while the bridge deck had to be able to carry the load appropriate for Class A according to the same Standard. As the precast WBS beams were in a very good structural condition and the substructure had been proved to have enough capacity to meet new requirements, rather than replacing the superstructure the Client decided to strengthen it. Few strengthening measures to increase the bending and shear capacity were con-sidered. It was then decided to look at bending and shear strengthening separately. Suffi-cient shear capacity was achieved through an application of a carbon fiber composite mats. Two layers of carbon fiber composite mats were used on both sides of webs for all precast beams. Strengthening to increase the bending capacity was carried out in several stages, since there was no individual measure / action that would sufficiently increase the bending capacity. At first the superstructure was made continuous by adding a concrete overlay. Additional longitudinal reinforcement placed in the concrete overlay was then required. Only after the execution of all aforementioned works was finished, the flexural capacity along the entire length of the bridge was guaranteed. The bridge was then reo-pened for traffic and has since been in service. Ten years after the strengthening the bridge is still in a very good structural condition despite a very heavy traffic on the bridge