Integrating Finite Element Modeling with Sensing System for Monitoring Composite Structures Using the Method of Neutral Axis

Structural Health Monitoring (SHM) is an engineering process that enables assessment of the condition and performance of structures. The method of the neutral axis has great potential as a feasible data analysis component of SHM for beam-like structures. However, the change in position of the neutral axis in composite steel-concrete multi-girder structures due to various damage types has not been fully understood. In this research, the method of the neutral axis was explored for a composite large-scale-model structure with artificially created damage in the concrete slab. Based on previous research, a downward movement of the neutral axis was expected at locations of damage. However, the unexpected upward shift of the neutral axis was observed from monitoring activities. The goal of this paper is twofold: first, to understand the conditions under which the neutral axis moves up in damaged cross-sections of composite beams; and second, to explore methods for damage detection and characterization in composite beam structures, informed by numerical modeling and based on a change in position of the neutral axis. A comparison between finite element model (FEM) results and measurements taken by strain-based monitoring system enabled important insights on behaviors of composite cross-sections under typical damage scenarios.