STUDY OF THE EFFICIENCY OF REINFORCED CONCRETE BRIDGES RECONSTRUCTION UNDER THE TYPICAL PROJECT VOL. 56 WITH BEAMS STRENGTHENING BY CHANGING STATIC SCHEME

Abstract

Purpose. Study of the actual nature of the spatial work and the regularity of the distribution of the temporary load between the beams of the existing simply supported cross-ribbed span structure and under various options for changing its static schemes, involving in joint work the reinforced concrete overlay slab and other new elements of the reconstruction. Methodology. In order to evaluate the effectiveness of the structural solutions used during the reconstruction of the expansion and strengthening of the span structure, it is planned to conduct a set of alternate tests with sequential introduction into its composition before each alternate test of one of the new structural elements of the reconstruction, involved in joint work with the existing beams. That is, for each successive test, the impact of only one factor was assessed, the inclusion of which in the composition of the existing span structure changed its operating conditions. The effectiveness of its application was evaluated by direct comparison of the deflections of the beams of the next tests with the deflections of the previous ones. Results of five (1… 5) span structure tests were carried out during successive stages of reconstruction, i.e. in the following sequence: 1 – test of the span structure in the existing state according to the simply supported static scheme; 2 – after installation of the horizontal immobility of the supporting parts; 3 – after complete pinching of the beams on the supports; 4 – after installation of the overhead plate of the expansion of the span structure on pinched beams; 5 – after completion of reconstruction before handover. The results of these tests were beam deflections and transverse distribution coefficients determined from them. The effect of joint work of new reconstruction elements with the existing beams was established by comparing the deflections of these beams from tests 1-4 under the same load schemes. We obtained the ratio f1:f2:f3=1:1.46:2.95, from which it is evident that the greatest effect of strengthening the beams is achieved in the static scheme pinched on the supports. The experimental transverse distribution coefficients turned out to be almost the same for all investigated static schemes, which indicates that the possibility of their spatial calculation using one method. The scientific novelty consists in the experimental and theoretical substantiation of the effectiveness and operational reliability and strengthening of beams of reinforced concrete span structures by changing the static scheme. Practical significance – wide application of the method of strengthening reinforced concrete span structures by changing the static scheme in the practice of their reconstruction.