Title:
Development of Compressive Fracture Energy Model for Confined Normal-Strength Concrete
Author(s):
Xiaoran Song
Publication:
Structural Journal
Volume:
121
Issue:
2
Appears on pages(s):
5-18
Keywords:
compressive fracture energy; confined concrete; crack band approach; mesh-size dependence; normal-strength concrete; strain softening
DOI:
10.14359/51740284
Date:
3/1/2024
Abstract:
The damage in reinforced concrete (RC) columns under concentric
compressive load conditions tends to localize within certain
regions. The softening branches of the stress-strain curves
for confined concrete are gauge-length-dependent. The sizedependent confined model, when applied to numerical simulations, will bring in mesh-dependency problems. This paper develops a compressive fracture energy model for confined normal-strength concrete to predict the strain-softening behavior of RC columns. The compressive load-deflection response data of 47 normalstrength RC columns under concentric load conditions are
collected to form a database. Then, an exponential function, with
the best fit to the tested post-peak softening curves, is adopted to
compute the compressive fracture energy. The effect of confinement
on the compressive fracture energy is studied, and an empirical
expression is proposed to predict the compressive fracture energy.
For validation, the proposed compressive fracture energy model is
introduced into a uniaxial concrete model to simulate the softening
responses of RC columns under large deformations. It is found that
the predicted force-displacement response without compressive
fracture energy regularization is extremely brittle, which deviates
significantly from the test results. While the proposed compressive
fracture model provides an objective and accurate prediction of the
softening responses of RC columns, it can also be used for collapse
assessment of RC structures against extreme load conditions.