Refined plasticity model for concrete stress-strain relationship part I : Prediction of peak stress and residual stress
- Authors: Piscesa, Bambang , Attard, Mario , Samani, Ali Khajeh
- Date: 2014
- Type: Text , Conference paper
- Relation: 23rd Australasian Conference on the Mechanics of Structures and Materials (ACMSM23) p. 149-154
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- Description: A refined plasticity model for concrete stress-strain relationships is proposed. The proposed failure surface has the ability to evolve its form based on empirical formulation in which being extracted from the experimental results via the frictional driver parameter (). Two main features are highlighted in this paper such as the peak stress prediction and residual stress prediction of the proposed model. In this paper the comparison of proposed models with experimental results weighted on uniaxial-triaxial compression in axial direction. In the next part of the research a non-associative flow rule in which has an inclusion of size effect to be applied in the constitutive driver is proposed and experimental comparison in both axial and lateral direction is discussed.
- Description: A refined plasticity model for concrete stress-strain relationships is proposed. The proposed failure surface has the ability to evolve its form based on empirical formulation in which being extracted from the experimental results via the frictional driver parameter (
Investigation on the fiber based approach to estimate the axial load carrying capacity of the circular concrete filled steel tube (CFST)
- Authors: Piscesa, Bambang , Attard, Mario , Suprobo, Priyo , Samani, Ali Khajeh
- Date: 2017
- Type: Text , Conference paper
- Relation: International Conference of Applied Science and Technology for Infrastructure Engineering 2017, ICASIE 2017; East Java, Indonesia; 5 August 2017; published in IOP Conference series: Materials Science and Engineering Vol. 267, p. 1-9
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- Description: External confining devices are often used to enhance the strength and ductility of reinforced concrete columns. Among the available external confining devices, steel tube is one of the most widely used in construction. However, steel tube has some drawbacks such as local buckling which needs to be considered when estimating the axial load carrying capacity of the concrete-filled-steel-tube (CFST) column. To tackle this problem in design, Eurocode 4 provided guidelines to estimate the effective yield strength of the steel tube material. To study the behavior of CFST column, in this paper, a non-linear analysis using a fiber-based approach was conducted. The use of the fiber-based approach allows the engineers to predict not only the axial load carrying capacity but also the complete load-deformation curve of the CFST columns for a known confining pressure. In the proposed fiber-based approach, an inverse analysis is used to estimate the constant confining pressure similar to design-oriented models. This paper also presents comparisons between the fiber-based approach model with the experimental results and the 3D non-linear finite element analysis.
3D Finite element modeling of circular reinforced concrete columns confined with FRP using a plasticity based formulation
- Authors: Piscesa, Bambang , Attard, Mario , Samani, Ali Khajeh
- Date: 2018
- Type: Text , Journal article
- Relation: Composite Structures Vol. 194, no. (2018), p. 478-493
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- Description: Strengthening reinforced concrete (RC) columns with external confining devices such as FRP wraps or steel tube is widely used in construction. By using external confining devices, both the strength and ductility of RC columns are significantly improved. However, numerical modeling to predict the capacity of strengthened RC columns is limited and often oversimplified. One of the biggest challenges in numerical modeling is to deal with unequal dilation between the concrete inner core (enclosed by both transverse steel and FRP wraps) and the concrete outer core (between the transverse steel and FRP wraps). Inaccurate modeling on the concrete dilatant behavior can lead to incorrect strength prediction. Sophisticated constitutive models which are able to model concrete dilation and robust modeling techniques are required. In this paper, three-dimensional non-linear finite element analysis (3D-NLFEA) of circular RC columns confined with conventional steel stirrups and FRP wraps is presented. In the FEA, the initial stiffness method with Process Modification (acceleration technique) is used to solve the equilibrium forces in the global solution. The constitutive model is based on the plasticity formulation proposed by the authors, which can capture the effective lateral modulus (EL) of the confining devices. This lateral modulus is obtained by observing the principal incremental stresses and strains at each element gauss point. It was found that, the lateral modulus is greatly affected by the boundary condition, dilatant behavior of the constitutive model and the Poisson's ratio of the external confining device. To validate the performance of the proposed model, several comparisons of the proposed model, using 3D-NLFEA, with experimental results is presented. The comparisons show that the predicted response using 3D-NLFEA and the experimental results of RC columns confined with FRP are in a good agreement.
Refined plasticity model for concrete stress-strain relationship part II : Inclusion of size effect
- Authors: Piscesa, Bambang , Attard, Mario , Samani, Ali Khajeh
- Date: 2014
- Type: Text , Conference paper
- Relation: 23rd Australasian Conference on the Mechanics of Structures and Materials (ACMSM23) p. 155-160
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- Description: This article will discuss about the implementation of size effect into the proposed plasticity model by adjusting the plastic potential function or flow rule. A new parameter (