|Duration||01. Mai 2020 – 30. April 2023|
German Research Foundation (DFG)
National Natural Science Foundation of China (NSFC)
Performance of underground concrete structures, subjected to multiple-coupled effects, is critical to the life-cycle serviceability and safety of structures. This performance depends on the quality of the constituents and its organization inside a concrete on different scale levels of observation. The proposed project mainly focuses on the response of underground concrete structures during the construction stage and its service period, whenever subjected to fire. The equations for the chemical hydration and dehydration reaction kinetics, needed to simulate the microstructure development of early-age concrete, as well as the degradation of concrete when exposed to high temperature, strongly depend on the unique properties of the concrete constituents and its associated reactivity. The influence of struture change on rates of chloride ingress will be taken into consideration. Thermoanalytical techniques and advanced microstructural testing methods are used to validate these equations when exposed to fire. A 3D reconstruction algorithm is developed to establish a digital model of representative volume elements (REVs) of concrete at different scale levels. With multiscale methods, such as stochastic asymptotic expansion techniques and micromechanics, a constitutive law of concrete is established, which serves as input for macroscopic thermo-hygro-chemo-mechanical coupled analysis of reinforced concrete elements and structures, and are compared with testing results. The research supports the understanding of the physical nature of the material performance and structural response of concrete subjected to multiple-coupled effects, which can be widely used for design and construction of underground structures.