A numerical model to predict the effect of corrosion on the dynamic behavior of reinforced concrete beams
Résumé
Corrosion of the steel reinforcements has been identified as one of the major pathologies which may occur in reinforced concrete (RC) structure. The objective of this study is to develop an efficient computational model of RC members, accounting for the rebar corrosion. Fiber beam elements are known for being efficient to carry out computations at a structural scale with a relatively low computational cost. The purpose of the present study is thus to take corrosion effects into account in a fiber beam element computation. The first requirement for the developed model is the ability to represent the damage induced in the concrete cover due to the swelling of the steel corroded bar. Therefore, an initial computation conducted on a fine mesh cross-section provides a precise damage field, which needs to be projected on a coarser mesh. This coarser mesh will be used in fiber beam elements for computations at the structural scale, in order to stay consistent with the requirement of a low computational cost. In this study, two field projection techniques are investigated. The first proposed approach is based on the use of the shape functions. An optimization algorithm is suggested to improve the projection results, namely the stiffness matrix at the cross-section scale. The optimization improves the results of the projection method, but does not enable the use of a mesh coarse enough to be included in fiber-beam elements for a dynamic computation. Thus, a second projection procedure is investigated, based upon diffuse approximation. Combined with the proposed optimization, this method leads to satisfying results at the cross-section scale. The projected damage fields have been used to compute the non-linear force-displacement curve of a beam subject to three-point bending. This test confirms the choice of the projection method.
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