Slim foundations will reduce not only concrete or wood, when casting smaller blocks or stripes, but also excavation need for base structures!
Figure 1. Punching reinforcement making foundations slimmer
Especially tall or heavy buildings will impose big point or linear loads transferred by columns and walls to the ground through foundations and thus need “deep” considerations for foundations.
Sturdy cages and consideration of reinforcement for different actions can reduce foundation size. Reinforcing however can have its limitation in space (congestion), or bending and fixing workability.
Ground slabs and footings is statically differently defined compared to free slab, due soil pressure, so maximum resistance according to European testing and specification (ETA) slightly more limited (over 80 % of that of a column). If this capacity is exceeded, you can see sudden failures, that can progress if soil below settles following the floor or foundation failure.
Figure 4. 3 General bearing-type failures of punching in foundation (slabs usually, explanations: civilblog.org: failures-of-foundation )
Although there is a limitation to lightening foundations, such as towers, a meter of foundation height can mean a lot in exploding, digging and pumping of fresh concrete. A thick foundation might need very high stirrups to prevent punching shear failure. Headed rebar studs on rail units can stand alone for the time of foundation reinforcement laying, and cast preparations, and need minimum tying time, not to mention avoid bending of reinforcement. (Figure 5)
Figure 5. Over 100m twin-towers in Bratislava, Slovakia with punching resistance achieved using stud-reinforcement
Figure 7 PSB - stud rails solving foundation punching with limited and expensive excavation possibilities in Budapest (completed 2013)
Figure 8. Akropole, Riga, LT – stud-rails reduced time and costs for efficient foundation size, avoiding reinforcement congestion (completed 2019)
Figure 9 Panorama city, Slovakia, Bratislava, https://www.peikko.com/reference/panorama-city/ (completed 2014)