Computational analysis of size effect and failure modes in reinforced concrete beams

This paper presents a computational approach for simulating the fracture behavior of reinforced concrete.Cracks are discretely modeled using zero-thickness cohesive interface elements, while the reinforcement is explicitly represented by elastoplastic Timoshenko beam elements.The interaction between reinforcement and concrete is captured through specially developed coupling elements.To demonstrate the performance of the proposed computational approach, two series of experiments on reinforced concrete beams without shear reinforcement subjected to four-point bending were numerically analyzed in a 3D setting.In the first series of tests, the SL series performed by Syroka-Korol and Tejchman, the beam size was scaled in two dimensions while the span-to-depth and reinforcement ratios were kept constant.The distinct feature of these tests is that the failure mode was consistent across all sizes, enabling size-effect analysis.In the second series, the S1 series by Suchorzewski et al., only the beam depth was scaled, while the span, load location, and reinforcement ratios remained unchanged.This series exhibited markedly different failure modes for each size, allowing the assessment of the capabilities of the proposed modeling approach to capture the effects of the shape and size on the mechanical response of reinforced concrete beams.The proposed computational approach effectively captures size-dependent peak loads, failure modes, and fracture patterns in all investigated tests.