A new simplified approach for predicting the bearing capacity of rectangular concrete four-pile caps

Abstract

Strut and tie models are mainly used to predict the critical failure mode of RC pile caps. The bearing capacity is determined by taking the lowest between flexural strength corresponding to reinforcement yielding and punching shear load of the concrete struts. However, the concrete-reinforcement interaction presents a key parameter for predicting failure mode and load-bearing capacity of rectangular four pile caps. The objective of the present study is to evaluate the strength capacity of RC pile caps by developing a simplified approach given by a unique equation considering both contributions of concrete and reinforcement corresponding to the failure mode. The proposed analytical approach considers the weakest coefficient of variation of (P test/ P model) using the experimental database selected by the observed failure mechanism (flexion or shear) to evaluate the combination of the contributions ratios; of steel and concrete. The results are on the safe side (min (P test/ P model) = 1) and improved with lower scatter when compared to design methods from the literature (COV = 8.8% for all failure modes) and CRSI Handbook code.