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Civil-Comp Proceedings
ISSN 1759-3433 CCP: 77
PROCEEDINGS OF THE NINTH INTERNATIONAL CONFERENCE ON CIVIL AND STRUCTURAL ENGINEERING COMPUTING Edited by: B.H.V. Topping
Paper 50
A Unified Failure Criterion for Finite Element Analysis of Concrete Structures P.E.C. Seow, S. Swaddiwudhipong and K.K. Tho
Department of Civil Engineering, National University of Singapore, Singapore Full Bibliographic Reference for this paper
P.E.C. Seow, S. Swaddiwudhipong, K.K. Tho, "A Unified Failure Criterion for Finite Element Analysis of Concrete Structures", in B.H.V. Topping, (Editor), "Proceedings of the Ninth International Conference on Civil and Structural Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 50, 2003. doi:10.4203/ccp.77.50
Keywords: failure surface, multi-axial loads, high-strength concrete, steel fibre-reinforced concrete.
Summary
It is observed through a survey of existing literature that researchers use different
failure criteria for concrete under different loading conditions. In addition, research
to develop a failure surface for high-strength and steel fibre-reinforced concrete
under multi-axial loads is still relatively new. In this paper, a unified, 5-parameter
failure criterion for plain, high strength and steel fibre-reinforced concrete is
proposed for concrete with strength ranging from 20MPa to 165MPa. It can be used
to determine the state of stress at failure in both confined and unconfined concrete
subjected to multi-axial loads. To facilitate the prediction of stresses at failure, a
method to obtain a closed-form solution is also developed. This new formulation
allows the constitutive model to be conveniently implemented in a finite element
package, thus enabling the engineer to model, analyse and design concrete structures
under complex states of stress.
The proposed failure surface for concrete is described by a tensile meridian,
As concrete exhibits a non-linear behaviour under load, its stress-strain curve
may be approximated by a step-by-step incremental approach using constitutive
models for plain and fibre-reinforced concrete developed by Tho et al. [1] and
Mattar [2], respectively. Knowledge of the stresses and strains at failure are required
to calculate the incremental tangential modulus at each step. To facilitate the
implementation of the proposed failure surface into a Finite Element package, a
closed-form solution for predicting the state of stress in concrete under
monotonically increasing, proportional, multi-axial loads is presented in this paper.
The state of stress at failure is given by the point whereby a line drawn through the
origin and the current state of stress pierces the failure surface. Since The proposed failure surface and constitutive models are implemented through a user subroutine in a well-established commercial Finite Element software, ABAQUS. Experiments of FRC plates under biaxial loads tested by Yin et al. [3] and a plain concrete deep beam under two-point loading by Kong et al. [4] are modelled. The analytical results show a good fit to the experimental results and demonstrate the ability of the proposed failure surface to be applied to various types of concrete under different load conditions. Together with the closed-form solution for determining the stress at failure in concrete, this failure criterion can be conveniently and efficiently implemented in a Finite Element analysis, thus aiding the engineer in the analysis and design of concrete under complex stress conditions. References
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