ABSTRACT
Loads are essentially transferred in pile caps through three-dimensional stress fields; therefore, three-dimensional strut-and-tie models should be used. Nevertheless, in some instances, two-dimensional models are possible to employ, which are easier to handle than 3D models. 3D models usually require less amount of reinforcement since the load path is direct and hence shorter; on the other hand, in 3D models, the geometry of struts and nodal zones may represent difficulty and therefore simplified geometry can be adopted. As a result of the spatial nature of pile caps, their struts and nodal zones are distinct from those of two-dimensional structure members. Struts in pile caps are surrounded with significant volumes of concrete with very low stress levels, called inactive concrete, and they play a role in improving the strength of struts. In addition, nodal zones in pile caps are bounded with three-dimensional stress fields. This chapter covers all these features of pile caps. Besides, it provides examples to illustrate the design procedure of pile caps subjected to vertical loads and moments employing 2D models and examples on strength assessment of pile caps using 3D modeling.
