Title: Strut-and-Tie Model for Punching Failure of Column Footings and Pile Caps

Author(s): Carl Erik Broms

Publication: Structural Journal

Volume: 115

Issue: 3

Appears on pages(s): 689-698

Keywords: pile cap; punching failure; size effect; spread footing; strutand- tie method

DOI: 10.14359/51702042

Date: 5/1/2018

Abstract:
A design method for spread footings and pile caps is presented. The model is in principle based on the strut-and-tie concept, but with the strut dimensions defined by compatibility conditions and therefore not possible to manipulate by the designer. Due respect is paid to the size effect—that is, the decreasing strength with increasing member size—which seems to be disregarded by common strutand-tie methods. Comparison with test results of column footings and four-pile caps in the literature demonstrates that brittle punching failure as well as yielding and brittle cracking failure can be predicted with very good accuracy.