Flexural strength of corroded reinforced concrete beams

Abstract

The analytical prediction of residual flexural strength of corroded beams has been revisited in the context of relatively larger size beams reinforced with larger diameter tension bars to exclude the size-effect of beams in the proposed modelling and to improve further the accuracy of the analytical method. Most of the past research, including that conducted by the authors, has used smaller size beam specimens to generate test data for modelling. A new experimental programme was undertaken using 48 beams of width 200 mm and depth varying from 215 to 315 mm, reinforced with tension bars of 16 and 18 mm in diameter. The beams were subjected to a varying degree of corrosion damage using accelerated corrosion and then they were tested in a four-point bending test to determine their residual flexure capacity. When the two-step analytical procedure, proposed by the authors in an earlier work to determine the residual flexural strength of corroded beams, was applied to the test beams used in this new experimental work, it was found that the theoretical predictions were consistently lower than the actual flexural strength of the beams. The search for a more compliant prediction method has been accomplished by proposing a new correction factor that replaces the previous one by correctly taking into account the size-effect of the tension bars. In order to show the accuracy of the proposed method, the test data published by other researchers have been compared with the values predicted by the proposed method. The comparisons clearly show that the proposed method yields values which are in good agreement with the test data from this and other experiments, lending confidence to the proposed method to serve as a reliable analytical tool to predict the flexural capacity of a corroded concrete beam.