Page 123 - Handbook of Materials Failure Analysis

118 CHAPTER 5 Failure analysis of reinforced concrete structures

among experimental and numerical results when B1T is considered. It was expected
as corrosion phenomenon is not accounted.
When B1CL is analyzed, good agreement is also observed among all refe-
rences considered. In this corrosion case, the proposed nonlinear model tends to
slightly overestimate the structural mechanical resistance, especially, after rein-
forcements yielding. It may be explained due to mechanical effects such as
spalling and reduction of yielding steel stress along time that are not accounted in
the model.

8 CONCLUSION

In this chapter, reinforced concrete structures subjected to chloride ingress, which
leads to reinforcements corrosion, were studied. The chloride ingress and its con-
centration growth along time were modeled using Fick’s law and the corrosion of
reinforcements was simulated using empirical equations presented in classical
references. Uniform and pitting corrosion approaches were considered. The
mechanical structural behavior was simulated using a robust and accurate non-
linear model, which is the main contribution of this chapter. The proposed non-
linear model uses algebraic FEM equations and considers the damage model of
Mazars to represent the mechanical degradation of concrete. Moreover, dowel
action, aggregate interlock, and stirrups stiffness are accounted. The mechanical
behavior of steel is simulated using elastoplastic approach with hardening. The
geometric structural nonlinearity is represented using updated Lagrangian
approach.
In the first application, the results obtained by the proposed nonlinear model were
compared to experimental and numerical responses available in literature. The
results obtained by the proposed nonlinear model presented good agreement with
those available in literature, indicating its accuracy and robustness, validating, there-
fore, the numerical nonlinear proposed FEM model.
Finally, the proposed nonlinear model was applied to the analysis of two rein-
forced concrete beams which were analyzed experimentally and numerically by
other researchers, assuming corrosion and noncorrosion cases. The comparative
of results indicates that the proposed nonlinear model is efficient in modeling such
type of structures. However, some phenomena such as spalling and reduction of
yielding steel stress along time may be considered in the future in order to improve
the accuracy of the proposed model.

ACKNOWLEDGMENT

Sponsorship of this research project by the Sa ˜o Paulo Research Foundation (FAPESP), grant
number 2014/18928-2, is greatly appreciated. This research is a part of the activities scheduled
by the research project USP/COFECUB 2012.1.672.1.0.