Investigation of the Effect of Alkalai-Silica Reaction on the Structural Behavior of Reinforced Concrete Beams Using the Finite Element Method

Many structures, such as dams, bridges and hydraulic structures suffer deterioration induced by alkali- aggregate reaction (AAR) which impairs the durability and safety of installations. Alkali-silica reaction (ASR) is an internal chemical reaction that appears in concrete between certain forms of siliceous aggregates and the alkaline pore solution in concrete. The result is a more or less crystallized silica - alkaline product which can exert pressures on the surrounding matrix. ASR induces concrete expansion and generally leads to loss of strength and cracking. The structural behavior of concrete which has been affected by ASR is difficult to model due to various random parameters that govern this chemical process. The aim of this paper is to investigate the effect of ASR on behavior of reinforced concrete beams using three methods. For this purpose, 100x150x1100-mm concrete beams were built in the laboratory and reinforced with different ratio of compression and tension bars. Then ASR and creep strains were modeled by reducing the elastic modulus of concrete and applying equivalent tension force. For the purposes of verifying the numerical methods involved, fourteen beams were conditioned in a suitable environment using similar dimensions and loading system. Experimental results on reactive concrete samples were simulated so as to test whether the model was capable of describing the behavior of affected reinforced concrete beams under service loads. The comparison reveals that finite element model had good compatibility with acquired test results.