Seismic performance of reinforced concrete columns confined with two layers of stirrups

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Reinforced concrete (RC) columns confined with two layers of stirrups (TS) are a novel type of RC column, which consist of two layers of stirrups and longitudinal reinforcement. In this paper, the seismic behavior of TS-RC columns is investigated through a series of experiments, in which six one-half-scale column specimens were subjected to axial forces and lateral cyclic loading. For comparison, an additional six specimens are included in Li et al. The design and details of all specimens correspond to the same, except for the axial compressive load ratio. The test variables include the axial compressive load ratio applied to the columns, the cross-section type, and the spacing of transverse reinforcement. All specimens failed in a flexural mode, showing stable hysteresis loops. Because of the confinement of the two layers of stirrups, the TS-RC column specimens exhibit excellent ductility and dissipated energy even at the axial load ratio of 0.4. The lateral forcedrift relationships, backbone curves, energy dissipation, displacement ductility, stiffness degradation, final damage observed, and damage index are presented and discussed. K E Y W O R D Saxial load ratio, column, confinement, cyclic loading, ductility, seismic behavior, two layers of stirrups

d_{PA} = \frac{δ_{m}}{δ_{u}} + \frac{β}{P_{y} δ_{u}} \int italicdE

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Experimental Programmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Cyclic behavior of reinforced concrete columns confined with two layers of stirrups

Sun

2019

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A new confinement scheme for reinforced concrete columns using stainless steel or glass fiber reinforced plastic

Lee

Kim

et al. 2020

A new lateral confining method is proposed for reinforced concrete columns in this study. The new scheme incorporates additional lateral confinements that are placed outside conventional lateral reinforcements within cross section of a column. Stainless steel wires or glass fiber reinforced plastic (GFRP) rings have been employed as the additional confinement. A total of seven reinforced concrete column specimens have been tested to validate the proposed new scheme. Primary parameters in the test are vertical spacing and volumetric ratio of the additional confinements amongst others. Lateral hysteretic response shows that specimens with the newly proposed scheme exhibit no strength degradation up to 6% of drift ratio, the specimen without such scheme displays somewhat sudden degradation at 5% of drift ratio. Experimental results also indicate that displacement ductility and energy dissipation of specimens confined by the additional confinements are greater than those of specimen without such confinements. Margin of safety with reference to the code‐specified ductility is 1.6, 2.2, and 2.1 for specimen with no confinements, stainless steel wires, and GFRP rings, respectively. In addition, energy dissipation ability reveals that specimens with the confinements show up to 50% higher than the specimen without confinements. In all, experimental observation confirms that the present approach is promising to provide an additional confinement and ductility. It is thus expected that the suggested scheme can be applied to reinforced concrete columns and be particularly effective for those members with relatively large vertical spacing of conventional lateral reinforcements.

Experimental and simulation study on seismic performance of steel‐PVA hybrid fiber cementitious composites‐encased CFST

Li,

Chen,

Cen

et al. 2024

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Six hybrid steel and PVA fiber cementitious composite (S&PFCC)‐encased concrete‐filled steel tube (CFST) columns were designed and fabricated, and the effects of axial compression ratio, core concrete strength grade and steel tube thickness on the seismic performance of composite columns were studied. The test results show that the increase of core concrete strength can obviously improve the bearing capacity and energy dissipation capacity of composite column and can restrain the strain growth rate of steel tube after yielding. Low axial compression ratio and thicker steel tube thickness can improve the overall seismic performance of composite columns. Three calculation methods are modified, and the modified An method can predict the lateral bearing capacity of composite column well. Finally, based on the OpenSees finite element software, the seismic performance of the CFST column wrapped in S&PFCC is simulated to verify the test, and the numerical study shows that the seismic performance of the composite column can be optimized by increasing the steel fiber content, while PVA fiber has a weak effect in the elastic stage, and can effectively improve the ductility of the composite column in the plastic stage.