Deformation Capacity of Reinforced Concrete Columns by ProQuest

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An effective approach is presented for estimation of the ultimate deformation and load capacity of reinforced concrete columns based on principles of axial-shear-flexure interaction. Conventional section analysis techniques are employed for modeling the flexure mechanism, and the simplified modified compression field theory is implemented for modeling the shear behavior of elements. Average centroidal strains and average concrete compression strains derived from the flexural model are implemented in the shear model and used to calculate shear deformation and concrete strength degradation. This approximate procedure can be easily implemented in a hand-calculation method in a few steps. The approach is employed for the estimation of the ultimate deformation of shear- and flexure-dominated reinforced concrete columns previously tested. The analytical results are compared with the experimental data and consistent, strong agreement is achieved. [PUBLICATION ABSTRACT]

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									 ACI STRUCTURAL JOURNAL                                                                                     TECHNICAL PAPER
Title no. 106-S20


Deformation Capacity of Reinforced Concrete Columns
by Hossein Mostafaei, Frank J. Vecchio, and Toshimi Kabeyasawa

 An effective approach is presented for estimation of the ultimate            transverse reinforcement ratios, longitudinal reinforcement
deformation and load capacity of reinforced concrete columns                  ratios, and scales ranging from one-third to full-scale
based on principles of axial-shear-flexure interaction. Conventional          specimens. The application of the MCFT as a shear model
section analysis techniques are employed for modeling the flexure             within the ASFI method, however, requires relatively intensive
mechanism, and the simplified modified compression field theory is            computation—a calculation process involving inversion of a
implemented for modeling the shear behavior of elements. Average
centroidal strains and average concrete compression strains derived
                                                                              3 x 3 matrix, and an iteration process converging five
from the flexural model are implemented in the shear model and                different variables, which might not be suited to engineers in
used to calculate shear deformation and concrete strength                     practice. In addition, the results of analyses by the ASFI
degradation. This approximate procedure can be easily implemented             approach suggested further studies on the onset of shear failure
in a hand-calculation method in a few steps. The approach is                  or ultimate deformation of reinforced concrete columns.
employed for the estimation of the ultimate deformation of shear- and            Considering the fact that columns with either dominant
flexure-dominated reinforced concrete columns previously tested.              flexure or shear response fail finally in shear, the main objective
The analytical results are compared with the experimental data                of this study was to provide a simple analytical model,
and consistent, strong agreement is achieved.                                 applicable for design in practice, for determining the critical
                                                                              conditions that result in the shear failure of reinforced
Keywords: axial deformation; axial-shear-flexure interaction; displacement-   concrete columns and the corresponding ultimate strength
based evaluation; ductility; ultimate deformation; ultimate strength.
                                                                              and deformation capacity. In this new analytical process,
                                                                              tension-shear failure across cracks, loss of concrete compression
                       INTRODUCTION                                           strength, and compression-shear failure were the main
   Although the behavior of reinforced concrete columns and
                                                                              failure mechanisms considered at the ultimate state for both
beams has been studied for more than 100 years, the problem
                                                                              shear- and flexure-dominant members. In addition, crushing
of estimating ultimate deformation at ultimate strength, or
                                                                              of cover concrete, bond failure, buckling of compression
the lateral deformation at shear failure, remains unsolved.
                                                                              bars, and rupture of reinforcement were other potential
Experimental studies by various authors1,2 revealed that
                                                                              failure conditions and were checked at the ultimate state.
reinforced concrete columns subjected to axial load and
lateral load with similar ultimate strength may fail in signif-
icantly different ultimate deformations. Although it is agreed                              RESEARCH SIGNIFICANCE
                                                                                Accurate estimation of the ultimate deformation and
that increasing the ratio of the transverse reinforcement will
                                                                              ductility of reinforced concrete elements has long been a
enhance the ductility of a column, determining the ultimate
                                                                              significant challenge and the aim of researchers. A new
deformation at which the element fails in shear is still a
                                                                              approach was developed to estimate both the ultimate
major challenge for engineers. Based on newly introduced
                                                                              deformation and load capacity of reinforced concrete
performance-based design philosophies for response estimation
                                                                              columns and beams. The proposed method can be used as an
of structures, one of the main performance properties in the
                                                                              effective analytical tool for the purpose of displacement-
design process is the ductility and deformability of the structure.
                                                                              and performance-based design.
The more ductility the structure possesses, the better the
performance and the more economical the design. Therefore,
it is essential to have and apply a suitable analytical tool to                             ASFI METHOD AND UN
								
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