Analysis of Corroded Steel Reinforced Concrete Beams

Date of Award

May 2014

Degree Type


Degree Name

Doctor of Philosophy (PhD)


Civil and Environmental Engineering


Riyad S. Aboutaha

Second Advisor

Vadrevu Murthy


Beam, Concete, Corrosion, Finite Element Analysis, Reinforced, Steel

Subject Categories



This research presents a new methodology for the evaluation of the residual flexural strength of corroded reinforced concrete (CRC) beams. A Finite Element Analysis (FEA) model that accounts for damaged material properties and geometry was developed and verified against experimental data conducted by several researchers. The FEA model showed good agreement with experimental data. After validation against experimental data, the FEA model was used to investigate a total of 145 reinforced concrete beams that covered many variables: span to depth ratio, tensile reinforcement ratio, compressive reinforcement ratio, concrete compressive strength, length of corroded zone, and type of applied load. Based on the outcome of the above data, a detailed analytical model was developed. The analytical model was verified against experimental and FEA data conducted by the author and other researchers. The analytical model was then used to perform a parametric study to investigate the effect of the following parameters on the ultimate strength of concrete beams reinforced with steel bars:

- Span to depth ratio

- Tensile reinforcement ratio

- Compressive reinforcement ratio

- Type of applied load

- Unbonded length

- Corrosion level

- Length of corroded zone

- Spalling of concrete cover

Both the FEA and analytical models were able to predict the residual capacity of corroded RC beams.

For beams with corroded tensile reinforcement, it was concluded that when the corrosion level is relatively high, the decrease in capacity is mainly because of the decrease in the steel reinforcement cross-sectional area and strength, due to corrosion, whereas the major cause of strength reduction for beams subjected to low corrosion levels is the loss of bond between steel and surrounding concrete. On the other hand, for beams with corroded compressive reinforcement, the loss of strength is primarily due to loss of concrete cover.

Moreover, it was observed that when the reinforcement ratio is less than 0.35% or the length of unbond is less than 60% of the span, all beams were able to maintain their original capacity.

Finally, a simplified practical analytical model was developed to allow engineers to compute the ultimate capacity of corroded RC beams subjected to different corrosion levels and lengths.


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