Validation of reinforced concrete pile caps using solid finite element limit analysis

There is no accurate and generally accepted method for modeling solid reinforced concrete structures with complex triaxial stress states. Recently, however, finite element limit analysis (FELA) has been proposed as such a method. FELA is a load optimization technique based on the theorems of rigid plasticity, here applied using the lower bound theorem, which aims to maximize the load carried by a structure subject to the constraints of stress equilibrium and the yield condition of the materials. The objective of this study is to show the capability of a FELA framework based on solid modeling in predicting the load bearing capacity of reinforced concrete pile caps. This is done by considering an experimental database consisting of pile caps supported by four piles. The pile caps in the database stem from 11 different sources and have different shapes, sizes, and reinforcement layouts. The capacity obtained from the FELA calculations shows a good correlation with the reported capacity from the experiments. Furthermore, when comparing the ratio of the calculated capacity to the reported capacity, it is found that the scatter of the observations is largest for a reported shear failure, while the scatter is small when the failure is governed by yielding of the reinforcement. It is concluded that the model is able to safely predict the capacity of the pile caps.