Numerical Modeling and Use of Settlement Reducing Auger Cast-In-Place Piles Below a Mat Foundation

The 45-story Great American Tower, the tallest building in Cincinnati, is not only changing the downtown skyline, but is an excellent case study of innovation in geotechnical engineering. This project is an excellent example of the use of technological advances in site characterization and soil-structure methods. When an opportunity arises to combine state-of-the-art concepts with advanced modeling tools, engineers need to combine knowledge and forward thinking to geotechnical solutions to promote the state-of-practice. The Great American Tower at Queen City Square in Cincinnati, Ohio combines a mat foundation with a limited number of auger cast-inplace (ACIP) piles, with the piles primarily acting as settlement reducers. Promoting the unique soil-structure interaction based foundation system required the use of sophisticated numerical modeling tools and seamless communication with the designers, contractor, and owner. Traditional standard penetration test boring data (SPT) was initially used to develop a numerical analysis of the soil-structure interaction using FLAC 3D software. The model was further modified with cone penetration (CPT) and pressuremeter testing (PMT), load test results on several ACIP pile elements of varying lengths, but all tipping above bedrock, and ongoing monitoring. Integrating industry knowledge, with sophisticated modeling techniques, has provided a successful real-world case study