Prediction of Long-Term Basic Creep Using Multiscale Modeling

Multiscale modeling using Mori-Tanaka homogenization was applied to explore the impacts of concrete composition on long-term basic creep. Aging of the concrete was explored applying solidification theory with a CEMHYD3D hydration model. Variation of water-to-cement ratio, aggregate-cement ratio, and aggregate modulus were investigated using the multiscale model, and results were compared to the B4 model. Aggregate-to-cement ratio had the largest influence among all investigated parameters on the total compliance. The effects of water-to-cement ratio were not consistent between the multiscale model and B4, arising from assumptions about the compliance of C-S-H as a function of water content. Aggregate modulus affected instantaneous compliance but had virtually no effect on creep compliance. Aging of elastic and viscoelastic parameters both followed inverse power laws, though limitations in the aging model were clearly apparent, highlighting the need for more complex modeling at finer scales or more effective homogenization techniques at the microscale.

Brock Hedegaard, PhD, PE, joined the Department of Civil and Environmental Engineering at UW-Madison as an Assistant Professor in 2014. He earned his Master's and Doctorate degrees under the guidance of Drs. Catherine French and Carol Shield at the University of Minnesota. There, he studied the long-term time-dependent behavior of post-tensioned concrete box girder bridges through finite element modeling and structural monitoring of the St. Anthony Falls Bridge in Minneapolis, MN. His current research interests include simulating disproportionate collapse of reinforced concrete systems subject to extreme events, substructural monitoring techniques intended to characterize structural damage using multiscale modeling, and time-temperature interactions of concrete materials.