Optimum confining effect in steel composite hollow RC column with inner tube under compressive load

Abstract

An internally confined hollow reinforced concrete (ICH RC) column offers strong and durable confinement by the reinforcement of the inner tube. When the concrete in an ICH RC column experiences axial pressure, an inward radial pressure is produced by the arching action. This radial pressure is resisted by the concrete and the inner tube.Previous research considered the outer pressure and inner pressure to be equal. However, the inner pressure acting on the inner tube is lower because it is partially resisted by the concrete. Therefore, to determine the optimum confining effect on the concrete by the confining condition, it was necessary to determine reasonable values for the inward and outward confining stress in ICH RC columns. In the current study, the confining effects of concrete in an ICH RC column were investigated and evaluated using finite-element (FE) analysis. Parametric studies were performed to determine the factors affecting the confinement of the core concrete in an ICH RC column. The hollow ratio was found to be the main factor affecting the internal confining stress in an ICH RC column. Using the results of FE analysis, estimation equations for the internal confining stress and a new modified equation for the failure condition were developed.

Behavior of Circular Hollow Steel-Reinforced Concrete Columns under Axial Compression

“…However, they did not consider the restraining effect of the steel tube on the concrete due to the shape of the internal steel tube's cross-section. Likewise, Won et al [3] stated that the embedded hollow steel tube not only restricted the peripheral hollow RC section of HSRC members during axial compression, but also enhanced their ductility and prevented brittle failure. In a separate study, Han et al [4] peripheral hollow RC section of HSRC members during axial compression, but also enhanced their ductility and prevented brittle failure.…”

Development and axial behavior of precast concrete wrapped square steel tube columns

“…They also concluded that the failure mode could be controlled by the thickness of the inner steel tube. Won et al (2014, 2019) experimented 20 different steel-composite hollow RC columns under uniaxial compressive load. They found that the local buckling of inner steel tube occurred after reaching the maximum strength, which induced a bifurcation point on the axial load versus axial strain curves.…”

Experimental Study of Composite Hollow RC Column under Uniaxial Compressive Load

“…The strength and ductility of the columns were enhanced by the continuous confining stress provided by the inner tube. The confinement of normal-strength concrete (NSC) for steel-composite hollow RC columns has been studied in the last few years [4][5][6][7]. Stress-strain models for confined concrete have been proposed based on the material model created by Mander [8] (Han et al [4]).…”

“…A nonlinear concrete model and a compressive strength model with normal-strength concrete were studied in experiments evaluating its column [6,7]. Won et al [5] studied the optimal confining stress on the core concrete through finite element analysis. Based on Mander's material The main objective of this paper was to investigate the compressive behavior of a steel-composite hollow RC column with an HSC of 50 MPa.…”