Lazar Georgiev

University of Architecture, Civil Engineering and Geodesy · Department of Transport Structural Facilities

p>The most spectacular and large bridge in Bulgaria and one of the largest in South-East Europe bridge in Sofia was put into operation at the beginning of October 1983. The bridge perform a multi-span, prestressed reinforced concrete construction with a total length of 2114 m, a total width of 21.5 m and an average height above the ground of about...

p>This article reviews the service condition of three pedestrian suspension bridges. They are located in the Rodopi mountains, outside urbanized area. These bridges are crossing Varbitza river at different locations along its length and are mainly used by the locals in order to access the railway line (stations) running along the river. All bridges...

p>The construction in 1892 of the prefabricated single-span arched open-spandrel steel /wrough iron riveted bridge in Veliko Tarnovo of total length of 81600 mm during the government of Stefan Stambolov symbolized the first step towards the modern development of his hometown within the newly created Bulgarian state. The revision of the data of the...

p>This article reviews the new superstructure and cable system for the pedestrian suspension bridge over Varbitza river, situated in Rodopi mountain of Bulgaria. The bridge connects the town of Momchilgrad with the village of Sedlare, bridging the river in a single span. The distance between the two concrete pylons is 169m. The span of the main ste...

p>The paper presents a precise analysis of the stress-strain behavior due to creep in statically determinate composite steel-concrete beam according to numerical method in comparison with EM method of Dischinger, take into account in EC4. The analysis is based on the results obtained by numerical solution with Volterra integral equations, derived f...

During the movement of the railway vehicles in the longitudinal direction, are realized chaotic movements in the transverse direction, also. The last lead to the appearance of forces that are transverse to the axis of the road. The actual normative documents for the design of railway bridges indicate different values of these forces, and the differ...

p>This article reviews the service condition of three pedestrian suspension bridges. They are located in the Rodopi mountains, outside urbanized area. These bridges are crossing Varbitza river at different locations along its length and are mainly used by the locals in order to access the railway line (stations) running along the river. All bridges...

The paper examines the interface between the nationally applicable construction gauge 1-CM2 in the Republic of Bulgaria and the European kinematic gauge GC. From previous studies it was found that the sections for gauge 1-CM2 do not allow the movement of rolling stock for gauge GC, as it is found that there is an outline of the construction gauge G...

p>In the University of Architecture, Civil Engineering and Geodesy in Sofia a research project has started in 2018 aiming to investigate the possibilities of local production and application of high- strength concrete (or even UHPFRC) for strengthening existing structures in Bulgaria. Under this project laboratory tests of steel orthotropic bridge...

p>The weight and design speed of the railway vehicles increases in time. As a result, the values of design loads grow up. In old Bulgarian standard [1] the equivalent nosing force is prescribed as 60kN. In the present EN1991-2 [2] this value is 100kN. Meanwhile, a significant part of the very old bridges is not designed for nosing forces. In cases...

p>Composite steel-concrete bridges are having wide implementation in the present bridge practice due to their advantages. On the other hand, composite bridges have complex time dependent behaviour due to long term processes in concrete – creep and shrinkage. Stress strain state is a function of the sequence of their construction. In general, buildi...

p>Significant number of bridges in Sofia municipality are in halfway of their exploitation period – they are between 30÷60 years old. At the same time, there is a lack of common methodology for condition assessment of existing bridges (road, railway, pedestrian). Another issue is that there is no Bridge Management Data System, where the information...

Application of composite steel and concrete bridge superstructures and particularly such with fully or partially encased steel girders in Republic of Bulgaria is discussed in the paper. It was chosen a particular bridge near Sofia with partially encased steel profiles built in 1994. It was elaborated a Finite Element Method (FEM) model, based on As...

This article presents the procedure commonly followed by the authorities in Bulgaria when an old steel railway bridge has to remain in service after the realization of a project for rehabilitation and upgrading of the railway line crossing the bridge. The procedure is illustrated by a case study of a steel railway bridge situated on the Skutare–Man...

p>This article reviews the possibilities of the application of Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) for strengthening existing steel and concrete structures in Bulgaria. Although the application of UHPFRC in structural engineering is increasing worldwide in the last decades, both for strengthening and for new designs, in Bulgar...

Reinforced concrete superstructure type "filler beam" would be appropriate in future reconstruction of such structures with span length of 5 - 30m. They can be applied in road and railway bridges as their advantages are significant. They have a small construction height, simplified installation, steel elements are simplified and produced in factory...

There are 331 steel bridges with total length 11201,70m in exploitation in the railway infrastructure of the Republic of Bulgaria. Significant part of those bridges is with "open type" deck including longitudinal and cross beams. The stress state of a standard bridge deck of an old steel riveted truss bridge along Sofia - Varna railway line at km 1...

This paper describes the construction and behavior of a large steel double twin truss launching gantry with total length 168m, designed by Dr. Eng. Borislav Bankov (1912÷1992), used for erection of prestressed concrete bridge girders with span up to 60m (weight up to 220ton) along the Hemus highway, Republic of Bulgaria. It consists of two twin fra...