The railway connection Pnˇovany–Bezdružice is a regional, non-electrified single-track. Pnˇovanský Bridge over Lake Hracholusky, which is a water reservoir filled by river Mže, is the largest bridge on this track. The bridge consists of five fields. The side fields are stone-arch structures. The central three fields are riveted steel frame structure with lower arcs design with half-sank roadway. The field span is 3 × 57 m. The total length of the bridge is 208.4 m. The substructure consists of two stone pillars founded in the river valley. The lower sections of the pillars have been flooded by the Lake Hracholusky. The height of the pillars above the original ground level is about 36 m. The original bridge has been built in 1898. From 2018 on this bridge has been replaced with a new technology.
The three new bridge sections have been pre-assembled on shore off the railroad on a platform in reversed position with the arc on top. Then the new section was rolled out with hydraulic pullers and cables in two phases: transversal to the track and longitudinal on the track. When in place exactly above the old section, the new section was integrated to the existing structure. Now the combined structure was turned 180 degrees with two split rotators on the pillar heads step by step – the new section in bearing function and the old one to be carried away on it and scraped.
The weight of all structures imposed the main load, including joint plates, shims, rivets etc. Wind load of 3 m/s was considered for the entire erection time with the resetting time of 2 years for the rollout and turning. The temperature ranges from 0 to +40 °C were taken into account. The first SCIA Engineer 2018 analysis model consisted of simple beam elements. This was gradually modified based on the results achieved using beam and plate elements as well as employing all types of eccentricities. The rotators were further analysed with geometric imperfections, geometric and material non-linearity including steel plastification in areas of local stress peaks. The bridge structures were significantly affected by individual launching steps. Therefore, a flexible method was used for the first internal forces calculation. Subsequently effects were summed up with spread sheets. Overloading in some elements of the old structure was identified – particularly horizontal bracing. According to this the model was refined including material non-linearity. Finally, the design has been assessed according to the CSN EN standards. The calculation has proven that the erection procedure is safe provided all specified rules are followed.
The test loading has been done with three railroad engines CˇSD T 679.1 with a total weight of 348 tons. The regular rail traffic has been re-opened 30 April 2019.
| Project owner | SŽDC s.o. Railway Infrastructure Administration | |
|---|---|---|
| Location | Lake Hracholusky, between Pnˇovany and Bezdružice, District Plzenˇ; CZ | |
| Architect | TOPCON SERVIS s.r.o. | Libor Marek |
| Structural Engineer | SMP CZ, a.s. University CVUT Prague | Petr Popsimov Jakub Dolejš |
| Steel Contractor | MCE Slany s.r.o. | Igor Chorovsky |
| Date of Completion | May 2019 | |
| Steel Tonnage | 3 × 180 tons |