STRUCTURAL BEHAVIOR OF R.C. FOLDED STRIP FOOTINGS

Folded foundations have been used as an alternative to the conventional flat shallow foundations, in situations involving heavy loads or weak soils. They can be geometrically shaped in many forms especially for continuous footings such as strip footing. The purpose of this study is introducing an alternative foundation shape that reduces the cost of foundations by reducing the amount of reinforcing steel through choosing the most effective folded strip footing shape. The study is performed in two main phases. First, experimental study is performed using eighteen (18) half scale footings of which nine (9) footings of rectangular shape and nine (9) footings of folded shape by folding angle of 20o. The experimental setup is composed of steel tank with dimensions of 2.5m length * 2.5m width * 2.10m height. The tank is filled with medium dense sand. A numerical study using the finite element software ADINA in also performed in which the soil underneath the footing is modeled with a nonlinear Mohr-Coulomb soil model with model parameters obtained from the experimental phase of the study. Experimental results showed that maximum compression stresses in footing body decreased within a range of 45%, and the tension stresses are also reduced by the same amount in folded strip footing when compared with conventional rectangular footing. Measured settlements also decreased within a range of 13% up to 25% in folded strip footings over the conventional rectangular ones. There is a good agreement between the numerical and experimental studies of which about 10% difference in settlements, and about 15% difference in compression and tension stresses.