Numerical modeling of early age cracks in concrete for long-Term evaluation of structure

Long-Term evaluation of the structure requires identifying failure conditions during the construction and service life of the structure. It is often performed using the structural health monitoring (SHM). Interpretation of the collected SHM data, however, requires proper understanding of the structural behavior. In this work we focus on the initial life of structure, with emphasis on early age cracking of concrete. Early age cracking occurs in restrained structural members due to mechanical, chemical or thermal effects. One such case was identified at Streicker Bridge at Princeton University. The bridge is equipped with fiber-optic strain and temperature sensors and previous works have identified the early age cracking through unusual high changes in strain measurements during the first eight days after concrete pouring. However, a detailed study of physical behavior during this phase has not been carried out at phenomenon scale and this work aims to fill this gap. In this paper, we developed the numerical model for the crack initiation and propagation in concrete at early age. Phase-field model of fracture used in this study was extended to incorporate the chemo-Thermo-mechanical effects during concrete setting. The effectiveness of the model is demonstrated by its ability to capture thermal cracks initiating and propagating inside the concrete domain during the early stage. The qualitative results agree with the interpretation of the measured changes in strain values observed at Streicker Bridge. The qualitative result provides new opportunities for future research using more detailed 3D models for quantitative comparisons.