Estimating Settlements

Langan at the Forefront of Soil-Foundation-Superstructure Interaction

It’s an age-old business question: does new technology cost money or save money? When it comes to new methods in soil foundation superstructure interaction (SFSI), which more accurately estimate potential building settlements, the answer is clear that it’s a wise investment.

In the last few years, numerical methods (finite element analysis) for SFSI have become more prevalent, particularly where its applications provide immediate value. For example, when designing foundations near tunnels, which is often the case in New York City, SFSI helps demonstrate how potential adverse effects on the tunnels can be avoided from the adjacent superstructure loads. For tall buildings with foundations in challenging soils, as in Mexico City or San Francisco where bedrock is deeper and not as hard as Manhattan, SFSI is becoming more of a norm. Moreover, estimating engineering and construction impacts on adjacent buildings – which applies to every city in the world – is better done using SFSI. In fact, for locations of high seismicity and very soft soils, SFSI is a requirement to obtain building permits.

“Langan’s geotechnical and seismic experts are at the leading edge of finite element analysis and SFSI, technology,” said Dr. Konstantinos Garcia-Syngros, Associate, an internationally known and respected seismic expert, who leads the firm’s SFSI practice. “Using these new methods, in conjunction with our 50 years of practical experience, allows for more accurate estimations of building settlement, which in many cases enables innovative yet cost-effective foundation designs.”

Konstantinos cited a recent high-rise in Brooklyn, which was next to a subway embankment. By using finite element analysis his team engineered a hybridized geotechnical design using a mat foundation with a minimum number of piles versus a fully-piled foundation. As a result, $30,000 in Langan SSI services saved $750,000 on the project on material costs alone– the kind of numbers that clearly reveal the difference between a cost and an investment.