Experimental and Numerical Analysis of the Ribbed Reinforced Concrete Fracture Behavior Based on the Mesoscale FE Model

This study presented a meso-model for the fracture analysis of the reinforced concrete (RC) structure. A modeling method of RC meso-structure was proposed, and the rebars were allowed to separate from the concrete. The model was built using the cohesive zone model (CZM). The zero-thickness cohesive elements were adopted to characterize the mechanical behavior of potential fracture surfaces and rebar–concrete interfaces. The constitutive model for concrete was developed by considering the damage relation and friction effect, and the corresponding constitutive for the rebar–concrete interface (especially ribbed rebar) was developed by considering the influence of normal separation on the tangential bond–slip relation. To validate the proposed meso-model, a series of ribbed RC beams with an initial notch was designed and tested by four-point bending loading to obtain different fracture patterns. Through comparison, the developed RC meso-model was validated to simulate the RC structure's fracture behavior appropriately. The influence of the rebar–concrete interface constitutive model on the simulation results was investigated. The investigation results indicate that neglecting normal separation would result in an overestimation of the structure's stiffness and bearing capacity (the peak load was overestimated by more than 10%). Finally, an analysis was conducted on the energy consumption during the failure process of the RC beams. It was found that the proportion of energy consumption during tensile failure of the beam decreased from approximately 86% to 89% in the early stage to approximately 43% to 52% in the later stage, indicating a transition in the beam's failure mode from tensile failure to shear failure.