Structural Performance and Bending Test of Deteriorated Reinforced Concrete Bridges


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Title: Structural Performance and Bending Test of Deteriorated Reinforced Concrete Bridges

Author(s): Takeshi Oshiro and Sumio Hamada

Publication: Special Publication

Volume: 88


Appears on pages(s): 39-58

Keywords: beams (supports); bend tests; bridges (structures); corrosion; cracking (fracturing); deflection; deterioration; field tests; performance; reinforced concrete; reinforcing steels; safety factor; strains; strength

Date: 11/1/1985

Recently, significant deterioration of concrete surface and corrosion of reinforcing bars have been observed, and the necessity for the structural evaluation of such bridges becomes urgent for safety considerations. The primary objective of this study is to investigate the structural performance of two deteriorated reinforced concrete bridges and isolated test beams cut out of the same bridges at the time of replacement. Field and bending tests were conducted from which the strength of existing bridges and isolated beams was observed. Correlations of the values of strength obtained from these two tests give important data to be used for evaluation of existing deteriorated bridges. From the results of general investigations, field tests and bending tests, the following conclusions are drawn; (1) From the results of field tests of Nakama Bridge, strains of reinforcing bars and deflections are rather close to Theory II uncracked gross section), whereas those of Yaka Bridge are located between Theories I (cracked section) and II. This indicates the varying effects of deterioration on main beams. (2) Beams in bending tests yield larger strains and deflections compared with those from tests; this shows that the rigidity of a beam that is part of an existing bridge is much higher than that expected from an isolated beam. (3) According to general investigations, these two bridges were highly deteriorated in appearance. However, ultimate strength of test beams is higher than that computed by ACI Code, indicating no significant losses of strength.