Multi-scale computational modeling for concrete damage by mixed pore pressures – case of coupled alkali–silica reaction and cyclic freeze/thaw

Abstract

9As one kind of porous media, concrete suffers from some kinds of ambient impacts which may owe to the 10 arising pore pressures. Freeze/thaw cycles (FTC) and alkali silica reaction (ASR) are such two typical impacts 11 that may happen together, and cause mixed expansive pressure in micro-pores but finally result in macroscopic 12 damage to concrete structures. In order to investigate the macro-mechanical behavior of concrete composites 13affected by the micro-events, a multi-scale computational model is developed based on the FEM computation 14program DuCOM-COM3 used in this study, the analysis system covers a wide range of scales from the 15 hydration of cement paste to up-scaled mechanics of bulk structural concrete with cracks. The micro-physical 16 events are computationally modeled by considering the coupling effect between ASR gel and condensed water 17in the mixed pressure and motion. The pressures and transport of pore substances are also linked with the 18 concrete matrix deformation at macroscale through a poromechanical approach, and will affect each other, 19reciprocally. Once the crack happens in the nonlinear analysis, both the micro-events (water and gel motion) 20 and the macro mechanics will be mutually interacted. Finally, different sequences of combined ASR and FTC 21 are simulated. The multi-chemo mechanistic computation can reproduce the complex events in pore structures, 22and further the macro-damages. The results show that ASR can reduce the FTC expansion for non-air-entrained 23 concrete but may increase the frost damage for air-entrained concrete. The simulation is examined to bring 24 about observed phenomena. 25

Seismic Fragility Assessment of RC Columns Exposed to the Freeze-Thaw Damage

“…The statistical parameters and experimental data of the peak strain of plain concrete listed in Table 1 are drawn in Figure 2. As seen from Figure 2a, the peak strain of concrete exhibited an overall upward trend [10,27,28]. As freeze-thaw cycles reached 300, the mean value of the peak strain increased by 1.3 times.…”

“…In order to fully consider the influence of the uncertainties of raw materials, specimen size, test process, and other factors on the freeze-thaw test results, this paper selected the representative test results from [10,14,[21][22][23] to establish the deterioration model of C30 concrete. The basic parameters of different specimens are given in Table 1.…”

“…By substituting Equations ( 1), ( 2) and (10) into Equation ( 4), the time-varying Mander model of plain concrete could be obtained.…”

“…Moreover, Wang and Petru [9] studied the bonding properties of concrete after the rapid freeze-thaw cycles in the fresh and salt water through the pull-out tests, and they also established a simplified trilinear constitutive model. Gong et al [10] explored the utilization of a multi-scale macroscopic mechanical damage simulation method regarding the performance of concrete via many freeze-thaw cycling and the silicic acid reaction tests.…”

Multi-scale Computational Modeling on the Equivalent Element Method for Freeze-thaw Damage of Concrete

“…Based on the multi-scale method, the comprehensive analysis of the mechanical properties of concrete under FTCs can be carried out by the DuCOM (Gong et al 2018) and the PPMC model (Bharadwaj et al 2019). According to the existing research, the surface concrete will peel off, and the boundary of temperature and humidity of concrete will change after the concrete peeling off.…”