Analytical verification of the ACI approach of estimating tensile strain capacity of mass concrete

by 1980- Seay, Cristina Diane

Mass concrete fill is being used for the support of a facility foundation in Oak Ridge, Tennessee. The facility design requires the support foundation to be relatively crack-free in order to attain the shear wave velocity of 6000 fps, which is necessary for acceptable structural behavior during a design basis earthquake. Specifications were developed for use during construction of the support foundation to ensure that the mix design, sequential placement, and curing are performed to standards that would best ensure a relatively crack-free product. The mix design and subsequent placement strategy were developed by using an American Concrete Institute (ACI) approach. A test pad was used to aid in a better understanding of the mass concrete fill support foundation behavior. To assess the correctness of the ACI approach, the objective of this research was to analytically verify this process by the combination of short and long-term temperature data coupled with a simple analytical finite element (FE) model of sequential vertical placements using the structural analysis program GTSTRUDL. The result was a final shear wave velocity of 7500 fps. Therefore, the project support foundation will meet its facility requirements by means of the current design specifications. In conclusion, the appropriateness of the ACI approach was verified by the combined use of field data and finite element analyses. Analytical modeling allowed for the input of the real time lab and field data to assess the behavior of the mass concrete, and provide the unique ability to model the sequential construction to capture the time dependent interaction between successful concrete lifts. ii