Title: Evaluation of Column Load for Generally Uniform Grid Reinforced Pile Cap Failing in Punching

Author(s): Honglei Guo

Publication: Structural Journal

Volume: 112

Issue: 2

Appears on pages(s): 123-134

Keywords: building code; pile cap; punching shear resistance; strut-and-tie model (STM).

DOI: 10.14359/51687420

Date: 3/1/2015

Abstract:
Currently, the punching shear resistance of pile caps is frequently evaluated empirically, and although the strut-and-tie model (STM) may be used to calculate the issue, the two weaknesses of STM—conservative nature and difficult configuration—hinder its rational solution. To attempt to solve these issues, this paper presents a generalized method of spatial STMs to evaluate punching shear resistance of general pile caps with uniform grid reinforcement (TPM). Based on results of the spatial strut-and-tie bearing mechanism of pile cap punching failure, three-dimensional (3-D) rather than two-dimensional (2-D) strut strength is derived. During this process, nonlinear finite element analysis in conjunction with the derivation of a gradual least-square method for multiple variables is adopted. TPM is verified by 98 specimens in the literature, whose parameters (reinforcement ratio of tension tie, punching-span ratio, concrete strength, pile number, and pile arrangement) vary, respectively; the comparisons with the other four methods are made. It is indicated that TPM is extensively applicable to the evaluation of the punching shear resistance of general pile caps with uniform grid reinforcement.