Interactive strut-and-tie-model for shear strength prediction of RC pile caps

Panatchai Chetchotisak , Sukit Yindeesuk , Jaruek Teerawong

Abstract

A new simple and practical strut-and-tie model (STM) for predicting the shear strength of RC pile caps is proposed in this paper. Two approaches are adopted to take into account the concrete softening effect. In the first approach, a concrete efficiency factor based on compression field theory is employed to determine the effective strength of a concrete strut, assumed to control the shear strength of the whole member. The second adopted Kupfer and Gerstle\'s biaxial failure criterion of concrete to derive the simple nominal shear strength of pile caps containing the interaction between strut and tie capacity. The validation of these two methods is investigated using 110 RC pile cap test results and other STMs available in the literature. It was found that the failure criterion approach appears to provide more accurate and consistent predictions, and hence is chosen to be the proposed STM. Finally, the predictions of the proposed STM are also compared with those obtained by using seven other STMs from codes of practice and the literature, and were found to give better accuracy and consistency.

Key Words

pile caps; discontinuity region; strut-and-tie model; shear strength

Address

Panatchai Chetchotisak — Department of Civil Engineering, Rajamangala University of Technology Isan, Khon Kaen Campus, Khon Kaen 40000, Thailand
Sukit Yindeesuk — Department of Highways, Ministry of Transport, Bangkok 10400, Thailand
Jaruek Teerawong — Department of Civil Engineering, Khon Kaen University, Khon Kaen 40002, Thailand

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