Deformations in the strut of two pile caps

Resumen

There are several models for the design of pile caps, one of them, is the strut and tie model. Struts are graphical representations of the flows of the compression principal stress, while, the tie represents the flows of the tensile principal stress. The NBR 6118:2003 [1] recommends the use of strut and tie model for the design and verification of pile caps. The use of simple strut and tie models is much used by engineers. Basically, the model consists in determining steel areas based on the traction tie and verifying the crushing of the concrete in the inferior and superior nodal zones (the interface between the inferior face of the pile cap and the pile is the inferior nodal zone and, the interface between the superior face of the pile cap and the column, is the superior nodal zone). The strut integrity is guaranteed when the stress intensities in the superior and inferior nodal zones are lower than the limit value. This limit value is determined in function of the mechanical properties of the concrete pile cap and the stresses in the strut are determined in function of the internal forces and the area of the inferior and superior nodal zones. The correct form of the diagonal compression inside the pile cap is unknown. In function of the experimental analysis of the principal compression strain, the geometric form of the strut to two pile caps submitted the centered and eccentric load is shown along with the intensity of the stress in the inferior nodal zone.