Rebuilding of the overpass in Khmelnytsky city
Students Name: Nuriddinova Zemfira Serianivna
Qualification Level: magister
Speciality: Bridges and Transport Tunnels
Institute: Institute of Civil Engineering and Building Systems
Mode of Study: full
Academic Year: 2020-2021 н.р.
Language of Defence: ukrainian
Abstract: Nuriddinova ZS Rebuilding of the overpass in Khmelnytsky city Master’s qualification work. - Lviv Polytechnic National University, Lviv, 2020. Project leader - Doctor of Technical Sciences, Professor Viktor Kvasha. The object of research is the overpass in Khmelnytsky, the possibility of strengthening it by installing a monolithic billboard. Subject of research On state and local roads, a significant number of reinforced concrete bridges of small and medium spans are used, massively built in the 50-70s of the last century from prefabricated reinforced concrete beams according to standard designs of various editions [1,2], . The vast majority of them do not meet the operational requirements, consumer properties and needs of modern transport in accordance with the requirements of DBN B.2.3-22 primarily in the size of the bridge deck, load capacity, safety and comfort. Due to defects and damages received in the course of long operation their reliability and durability are not provided and bearing capacity of beams is limited. For further normal operation, the reconstruction of these types of span structures is very necessary to bring their performance in line with the requirements of the design standards of new bridges. At the maximum preservation and use at reconstruction of existing designs of girder structures the considerable part of means will be saved than at full reconstruction. The purpose of the study is to strengthen and expand the overpass, with the maximum preservation of existing structures and thus reduce the cost of its overhaul [3,4]. Research results - In this master’s qualification work a project of overhaul of the overpass through the railway tracks on Kamenetskaya Street in Khmelnytsky is being developed. The master’s qualification work is developed according to DBN B.2.3-22-2009 "Bridges and pipes". Basic design requirements "and DBN B.1.2-15-2009" Bridges and pipes ". Loads and impacts" [5,6]. During the overhaul, the existing span structure is expanded to G 15 + 2 ? 1.5 m with a monolithic reinforced concrete billboard with the addition of new beams with asymmetric (short and long) cantilever sections to the end beams. The bridge deck is equipped with a standard semi-rigid metal barrier safety fence and railing. To strengthen the extreme, most damaged beams and ensure the load-carrying capacity of the extended span structure for normalized temporary loads A15 and NK-100, as well as to protect the open and most damaged external surfaces and reduce the departure of the console plate, new asymmetric and long consoles. In order to unload the beams in the span for the possibility of perception by them without amplifying the normalized loads A15 and NK-100 during reconstruction, the separate static scheme of the existing span structure is transformed into a 3-span inseparable with the elimination of expansion joints over intermediate supports. The created continuity makes it possible to reduce the span bending moments due to the emergence of new over reference points. Thus, the necessary calculation of reinforcement of existing beams is achieved. The most favorable variant of creation of indifference to the device of an overlay plate after removal of all elements of a bridge cloth, ie at the minimum constant loading - only from own weight of beams is accepted. The indistinguishability over the intermediate supports is created by concreting in the gaps between the support diaphragms of the existing beams of powerful reinforced support ribs, combined with the overlay plate, which is additionally reinforced with grids in the support areas for receiving the bending moment. For concreting the bottom slab, the top shelf of the existing beams in the respective areas is removed to provide free access to the concreting area. The interoperability of the overhead plate with the existing beams is ensured by their connection by means of flexible loop anchors welded to the locally exposed upper longitudinal reinforcement 2O32mm in each rib. After the main reconstruction works, the complete replacement of the bridge deck elements is performed, as well as a set of repair and restoration works to protect open surfaces from the aggressive influence of the environment to ensure the normalized durability of the reconstructed overpass. Verification calculations of the main structures of the bridge were carried out according to the norms of designing new bridges for the standardized temporary loads A15 and NK-100 provided by these norms in force for the period of inspection. With corresponding standardized reliability coefficients for permanent and temporary loads and dynamics coefficients. Reliability coefficients for constant loads within certain limits were adjusted in the direction of their reduction in accordance with the actual size of the elements of the girder structure and support according to the results of survey and measurements in kind. Verification calculations of the main structures of the bridge were carried out according to the norms of designing new bridges for the standardized temporary loads A15 and NK-100 provided by these norms in force for the period of inspection. With corresponding standardized reliability coefficients for permanent and temporary loads and dynamics coefficients. Reliability coefficients for constant loads within certain limits were adjusted in the direction of their reduction in accordance with the actual size of the elements of the girder structure and support according to the results of survey and measurements in kind. The span structure according to TP issue was subject to calculation. 56, calculated according to the norms in force for the period of design for other normalized temporary loads H-18 and NK-80 of average run l = 22.16 m. List of used literature sources: 1. Matarov IA Prefabricated reinforced concrete bridges with multi-row welded reinforcement. / Matarov IA, Smirnova LS, Shilina AL // -M .: Avtotransizdat, 1959. - 186p. 2. Standard projects of constructions on highways. Issue 56. Reinforced concrete span structures, prefabricated with frame reinforcement of periodic profile. / -M .: Stroyizdat, 1958. -56 p. 3. Kvasha VG Bridges and overpasses, reconstructed according to the projects of the Branch Research Laboratory №88 (GNDL-88) of the National University "Lviv Polytechnic" (catalog) - monograph / VG Kvasha. Kvasha // Lviv: Lviv Polytechnic National University, 2017. -53 p. 4. Kvasha VG Complex researches of reinforced concrete beam span structure of the bridge during its reconstruction / V.G. Kvasha, VS Rachkevich // Nauk.-tehn. production and inform.-analytical journal "Science and Construction". –K .: NDIBK, 2018.-№2. -with. 68-77. 5. DBN B.2.3-14: 2006. Transport facilities. Bridges and pipes. Design rules. –K .: Ministry of Regional Development, 2006.-359 p. 6. DBN B.2.3-22: 2009. Transport facilities. Bridges and pipes. Basic design requirements. –K .: Ministry of Regional Development of Ukraine, 2009. -73 p.