Finite Element Analysis of Bond for Reinforced Concrete Structures

A high-resolution finite element model is developed using the MSC.Marc software package to investigate local bond behavior and the modeling of this behavior. In the model, interaction between concrete and steel is treated geometrically as contact between two separate bodies. Concrete is modeled as a homogenous material. A multiple, fixed, smeared crack model is used to simulate response in tension, and a plasticity model with hardening-softening is used to simulate response in compression. To validate the model, analysis results are compared with laboratory data for “pull-out” and “uniform tension” bond tests. Three pull-out test specimens have no, light and heavy confinement; one uniform tension test specimen has no confinement. Analysis results are evaluated on the basis of global load-displacement history as well as the pattern and progression of concrete cracking and crushing in the bond zone. In the laboratory, global load-displacement response is measured using traditional instrumentation and bond-zone damage patterns are observed via X-ray CT of test specimens during testing. Results show that the proposed model simulates well bond strength and local bond-zone damage patterns. Using the proposed model as a reference model, a parameter study is conducted to investigate the impact of modeling decisions and bond-zone design parameters on predicted response.