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During the last 50 years a half thousand of bridges with the castellated steel beams were constructed in Poland. The concentration of welding and rolling residual stresses, low impact toughness of steel and the influence of low temperature, impact loads and fatigue caused the collapse of several this kind of bridges. The detailed inspection, evaluation and material investigations have shown that the welded area near the holes is endangered with brittle fracture even if not loaded. The problem, how to strengthen the existing bridges and to prevent the possible future failure, had to be solved. The paper discusses the method and the results of tests on a three-span road bridge with steel open-work beams, carried out during and after the execution of its reinforcement. The aim of the tests after the bridge had been reinforced was to determine how the spans structure behaved under load in order to verify the adopted assumptions and the methods used in static calculations, in particular the transverse distribution of loads among individual main beams and an evaluation of the real rigidities of these beams. The practical experience gained from the tests and the observations of the structure's behaviour made during the tests as well as an analysis of the results obtained from the measurement and their comparison with the calculations allow to draw the following general conclusions. The method used for the strengthening the bridge with the open-work beams (the castellated steel beam) turned out to be advisable and effective and the adopted static diagram of the structure corresponds to its real behaviour. The simplifications made result in deviations that increase the reliability of the structure. In the light of the tests, the three span structures can be accepted without any reservations. The mean values of the total deflections and stresses were smaller than the calculated theoretical ones. Composite spans of this type exhibit much greater rigidity than the one indicated by static calculations. These differences, constituting a reserve of load capacity in such structures, may be due to the additional tensioning of the concrete in the protective layer.
During the last 50 years a half thousand of bridges with the castellated steel beams were constructed in Poland. The concentration of welding and rolling residual stresses, low impact toughness of steel and the influence of low temperature, impact loads and fatigue caused the collapse of several this kind of bridges. The detailed inspection, evaluation and material investigations have shown that the welded area near the holes is endangered with brittle fracture even if not loaded. The problem, how to strengthen the existing bridges and to prevent the possible future failure, had to be solved. The paper discusses the method and the results of tests on a three-span road bridge with steel open-work beams, carried out during and after the execution of its reinforcement. The aim of the tests after the bridge had been reinforced was to determine how the spans structure behaved under load in order to verify the adopted assumptions and the methods used in static calculations, in particular the transverse distribution of loads among individual main beams and an evaluation of the real rigidities of these beams. The practical experience gained from the tests and the observations of the structure's behaviour made during the tests as well as an analysis of the results obtained from the measurement and their comparison with the calculations allow to draw the following general conclusions. The method used for the strengthening the bridge with the open-work beams (the castellated steel beam) turned out to be advisable and effective and the adopted static diagram of the structure corresponds to its real behaviour. The simplifications made result in deviations that increase the reliability of the structure. In the light of the tests, the three span structures can be accepted without any reservations. The mean values of the total deflections and stresses were smaller than the calculated theoretical ones. Composite spans of this type exhibit much greater rigidity than the one indicated by static calculations. These differences, constituting a reserve of load capacity in such structures, may be due to the additional tensioning of the concrete in the protective layer.
Inspection, evaluation, strengthening and testing of reinforced composite bridge with steel castellated beams
Inspektion, Bewertung, Verstärkung und Testen von Verbundbrücken verstärkt mit Trägern mit durchbrochenen Steg
Manko, Z. (author)
Structural Steel Developing Africa, 1996 ; 177-184
1996
8 Seiten, 5 Bilder, 3 Tabellen, 4 Quellen
Conference paper
English
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