CURRENT STATE OF THE PROBLEM OF RECONSTRUCTION OF HIGHWAY BRIDGES

Abstract

The article describes structural and technological solutions of the most commonly used type of reinforced concrete bridges, which have been massively constructed using typical designs of 1950-60s, the age of construction industry reorientation towards prefabricated concrete construction. Among those systems are: prefabricated cross-ribbed (diafragme) spanning constructions with multi lined framing rebars - Typical Project, TP‘56; ribbed slabs (non-diafragme), designed by PI “Souzdorproekt” in 1962 as improved TP ‘62 (TP ‘56d - with additions in 1962); spanning structures of prefabricated prestressed concrete string-shaped beams, designed by “Ukrderzhdor” NDI (“Derzhdor” NDI). The article shows an overall characteristics of those spanning construction types, their advantages and disadvantages, track record of their common defects and damages caused by pour exploitation, as well as conditions and opportunities to use them during reconstruction and further exploitation.

There is a disorder in the question of bridge reconstruction and design. Underqualified and inexpensive designs having no experience in reconstruction projects as well as technical or economic justification, by calling a project a “Reconstruction” mean a complete rebuilding of a bridge using completely different structural scheme and building systems. This leads to 3-3.5 times budget increase in comparison to the  reconstruction by prolonging an existing structure lifespan. This is not a good strategy. Introducing a brand new structure to the existing bridge can not be called a reconstruction. It’s a new construction. The spanning structures need new typical reconstruction projects to be developed featuring cost effective solutions.

The proposed system for bridge reconstruction is efficient and relatively cost effective. Designed and tested by HNDL-88 it’s also been implemented in multiple cases of bridge reconstruction. In essence it is a widening of the existing structure by overlapping it with prefabricated concrete topping slab which has wide side overhangs of about 3.5-4 meters, combined with existing beams additional reinforcement and their static scheme alteration from disectional to non-disectional or completely fixed to the supporting pillars.

The problem of bridge reconstructions need to be addressed in a holistic way with a consistent investment, with the following phase: reconstruction project, reconstruction process planning, and further exploitation plan.