ESTIMATING THE PUNCHING SHEAR CAPACITY OF REINFORCED CONCRETE PILE CAPS
Journal
World Conference on Earthquake Engineering proceedings
Journal Volume
2021
Start Page
3f-0040
ISSN
30065933
Date Issued
2021
Author(s)
Abstract
Reinforced concrete pile caps are commonly used in the foundations of buildings and bridge structures. The design of pile caps should be carried out judiciously, considering both the bearing capacity of the soil and the strength of the pile caps. Pile caps experience significantly high punching shear forces transferring the load from the structure to the soil. Accurate estimation of shear strength is required to carry out a safe and economical design of pile caps. Currently, the strength of pile caps estimated through ACI code considers only the pile cap dimensions and concrete strength while ignoring other key parameters such as the contribution of tension steel and the positioning of columns, which is likely to produce estimations with large errors. In this paper, load resisting paths in the D-region near the column connecting with the pile slab are discussed and the shear strength of reinforced concrete pile caps is evaluated using the softened strut-and-tie model. The proposed model satisfies force equilibrium, strain compatibility and constitutive relationships of the cracked concrete. It can also accurately estimate cracking and strength points and provide a force-displacement load path for reinforced concrete pile caps. The predicted shear strength values are compared with the test results for six pile cap specimens reported previously with varying geometry and reinforcement configurations. The comparison showed an excellent correlation between the predicted shear capacity and force-displacement load path with the test results. The proposed model also provided much better estimates for shear capacity than the ACI code for all the specimens.
Subjects
analytical model
pile cap
punching shear
shear strength
strut-and-tie
Publisher
International Association for Earthquake Engineering
Type
conference paper