Carrying capacity of reinforced concrete beams of the compound cross-section of the span structures of bridges, extended by the paving slab

Abstract

Problem. Experimental studies of load-carrying capacity of full-scale reinforced concrete bridge beams of typical 56 type project are described. The beams were dismantled from the existing bridge after 40 years of its operation and combined with fragments of precast-monolithic and precast ribbed paving slab, were used during the reconstruction of the old span structures for widening and simultaneous strengthening of their beams by way of extending the transverse section from above. Goal. Three prototypes of full-length reinforced concrete bridge beams with a total length of 14,06 m were tested, which had a folded cross-section, including a tare section of an existing beam of 0,85 m high and a fragment of a ribbed precast or precast monolithic plate, extended from above for joint work. Thus, the total height of the folded section of the reinforced prototype beams was 1,27…1,29 m. Methodology. The technique of testing the beams of the composite section was to obtain the maximum number of experimental data on a limited number of prototypes, in particular their carrying capacity for normal and inclined cross-sections. For this purpose, during the tests, different schemes of their loading with one or two concentrated forces were created for obtaining different types of destruction on the same prototype – by bending moment and transverse force. Originality. Therefore, the load-carrying capacity of the test beams in both normal and inclined cross-sections were studied. The main purpose of these studies is to evaluate the impact of the inclusion in the joint work with the existing beams of ribbed paving slab on the increase of their carrying capacity both in zonal moment and in transverse force compared with the carrying capacity of the only existing beams. Results and practical value. As the main result of the research, it was found that after the inclusion in the joint work of the ribbed paving slab the carrying capacity of normal and inclined cross-sections increased by 1,55-1,65 times, which is sufficient to provide load capacity of the expanded paving slab of bridge structures.