Identifying and mitigating damage in concrete structures at an early stage is crucial for minimizing the associated maintenance and repair costs. Weak material degradation, such as load-induced initiation and propagation of microcracks, is a precursor of localized damage (macrocracking) in concrete structures and can be detected by means of multiple-scattered late arriving ultrasonic signals, also called coda signals [1]. In this regard, we leverage the capabilities of computational modelling to effectively translate features of coda signals into information regarding the level of degradation in concrete. To this end, a virtual concrete lab [2] is proposed to investigate effect of weak damage on the coda signal variations. Our framework integrates multiscale computational modelling, forward wave simulation, and feature extraction. At the specimen scale, we employ realistic mesoscale concrete models [3], simulating damage initiation and propagation using a novel reduced order multiscale method [4]. The concrete specimens subjected to specific level of damage in the virtual lab are subsequently analysed through wave propagation simulations. Features extracted from synthetic coda signals demonstrate good agreement with experimental data, establishing the reliability of our proposed framework in capturing changes in coda signals and correlating them with the level of damage in concrete in a quantifiable manner. Finally, a strategy for using specimen scale information for predicting the state of damage at the structural scale will be presented. REFERENCES [1] Snieder, R., Grêt, A., Douma, H., & Scales, J. (2002). Coda wave interferometry for estimating nonlinear behavior in seismic velocity. Science, 295(5563), 2253-2255. [2] Vu, G., Meschke, G., Timothy, J. J., & Saenger, E. H. (2023). A virtual lab for damage identification in concrete using coda waves. In Life-Cycle of Structures and Infrastructure Systems (pp. 1834-1841). CRC Press. [3] Vu, G., Diewald, F., Timothy, J. J., Gehlen, C., & Meschke, G. (2021). Reduced Order Multiscale Simulation of Diffuse Damage in Concrete. Materials, 14(14), 3830. [4] Holla, V., Vu, G., Timothy, J. J., Diewald, F., Gehlen, C., & Meschke, G. (2021). Computational generation of virtual concrete mesostructures. Materials, 14(14), 3782.