Bar buckling in ductile RC walls with different boundary zone detailing: Experimental investigation

Tripathi, Mayank; Dhakal, Rajesh; Dashti, Farhad

doi:10.1016/j.engstruct.2019.109544

Cited by 27 publications

(19 citation statements)

References 38 publications

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“…These cracks widened and extended during the last cycle of 2% drift (loading the left side) and 2.5% drift (loading the right side). Such in‐plane and out‐of‐plane diagonal cracks were not reported in previous studies on slender rectangular walls under unidirectional loading 1,12,29,31,50–53 . Based on the results of this experimental study, it can be concluded that asymmetric bi‐directional loading (eg, skewed loading) can trigger the development of diagonal cracks in the out‐of‐plane direction of RC slender walls.…”

Section: Discussion Of the Test Resultssupporting

confidence: 41%

Experimental study on the effects of bi‐directional loading pattern on rectangular reinforced concrete walls

Niroomandi

Pampanin

Dhakal

et al. 2021

Earthq Engng Struct Dyn

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In this experimental study, three identical reinforced concrete (RC) walls were tested under three different lateral loading patterns. These loading patterns were cyclic in‐plane, skewed with 45° angle and clover leaf. The main objective was to investigate the effects of these bi‐directional loading patterns on the seismic behavior of slender rectangular RC walls. The results showed significant increase in tensile and compressive strains in concrete and longitudinal bars that led to earlier cover concrete spalling and bar buckling in the specimens subjected to bi‐directional loading. The neutral axis depth and compression zone were found to be substantially larger when subjected to bi‐directional loading and this led to the occurrence of concrete crushing and bar buckling in the web. Moreover, lateral instability failure triggered earlier in the specimens under bi‐directional loading, as a result of reduction of out‐of‐plane stiffness of the wall. However, bi‐directional loading did not significantly increase out‐of‐plane buckling of the wall in terms of out‐of‐plane displacement. In‐plane and out‐of‐plane shear cracks formed in one of the specimens subjected to bi‐directional loading, whereas the same wall under in‐plane loading developed only flexural cracks. It was also found that in‐plane shear deformation was larger when the wall was subjected to bi‐directional loading. The results of this experimental study emphasize the need for further investigation of the effects of bi‐directional loading on RC structural walls.

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Section: Discussion Of the Test Resultssupporting

confidence: 41%

Experimental study on the effects of bi‐directional loading pattern on rectangular reinforced concrete walls

Niroomandi

Pampanin

Dhakal

et al. 2021

Earthq Engng Struct Dyn

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“…However, reducing the spacing of transverse reinforcement increases the buckling-induced demands imposed by longitudinal reinforcing bars on transverse reinforcement, therefore requiring larger transverse reinforcement to restrain longitudinal bar buckling within single tie spacing. This explains why in walls tested in the literature [3,5,6], providing closely-spaced stirrups resulted in increased buckling of longitudinal reinforcing bars.…”

Section: Mechanics-based Design Of Anti-buckling Transverse Reinforcementmentioning

confidence: 98%

“…In addition, the possibility of bar buckling spanning multiple tie spacing is not given due consideration in the design codes by presuming that the confinement reinforcement is always adequate to restrict the bar buckling between successive ties. However, past research has shown that this is inaccurate and if not quantified, can have serious repercussions on the seismic performance of RC structures [5,6]. For instance, in a RC member with transverse reinforcement spaced at 6db, if the anti-buckling transverse reinforcement is inadequate to restrict bar buckling to single tie spacing, bar buckling can span multiple tie spacing (as shown in Figure 1), causing a significant reduction in compressive stresses at relatively small strain demands.…”

Section: Design Of Transverse Reinforcement In Rc Wallsmentioning

confidence: 99%

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Designing and detailing transverse reinforcement to control bar buckling in rectangular RC walls

Tripathi

Dhakal

2021

BNZSEE

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Bar buckling in RC structures is a commonly-observed failure mode that adversely affects their deformation capacity. To restrict bar buckling in ductile RC walls, design codes only emphasises on restricting the spacing of transverse reinforcement and does not recognise the importance of the effective stiffness of the ties (which is a combination of the tie leg axial stiffness and spacing) to restrict bar buckling. Therefore, in this paper the design requirements for anti-buckling transverse reinforcement are summarised, and improvements to the current design methodology for anti-buckling transverse reinforcement are proposed. To ensure that the transverse reinforcement detailing in plastic hinge regions is adequate to restrict bar buckling to single tie spacing and the compressive stress deterioration in bars due to buckling is controlled, refinements to the current detailing procedures are proposed. The buckling restraining ability of transverse reinforcement depends on the axial stiffness of the tie legs, while the compressive stress reduction in reinforcing bars due to buckling depends on their unsupported length (in bare bar tests) or buckling length that can include multiple tie spacing (inside RC members). Therefore, restrictions on both the axial stiffness of the tie legs and spacing of transverse reinforcement along the longitudinal reinforcing bars are proposed. The effective axial stiffness of tie legs is controlled by ensuring that the length of the tie legs in the direction of potential buckling is well below the critical length evaluated using a mechanics-based approach. Additionally, compressive stress degradation in reinforcing bars is controlled by limiting the ratio of the transverse reinforcement spacing and the longitudinal bar diameter such that any reduction of compressive stress carried by the longitudinal bars due to buckling at the limiting curvature recommended by New Zealand Concrete Standard is within an acceptable range. Furthermore, recommendations to avoid buckling of unrestrained reinforcing bars in the boundary zone and the wall web are proposed. Using the proposed design methodology, buckling of longitudinal reinforcing bars in ductile RC walls can be delayed and the detrimental effects of buckling on the lateral response of walls can be controlled until the design drift or curvature demands are met.

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“…Damage to reinforced concrete columns during earthquakes in California, Japan, Turkey and Iran from 1994 to 2003 [9] was divided into two categories: bending and shear damage, and the lack of adequate ductility for bending of the columns and horizontal migration of the column nodes cause large deformations. In the research of reinforced concrete columns with different types of transverse reinforcement [10] and in the research on walls [11], several typical forms of rebar buckling were reported. According to these studies, the shapes of buckled bars in reinforced concrete columns depends on the configuration of stirrups and of their diameter and spacing, and global buckling occurs when stiff ties with small spacing are used.…”

Section: Bucking Form Of the Rebarmentioning

confidence: 99%

Influence of Geometric Imperfections on Buckling Resistance of Reinforcing Bars during Inelastic Deformation

Korentz

2020

Materials

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This paper presents the results of numerical simulations on three main factors and their influence on the buckling resistance of reinforcing bars and on their behaviour in the range of postcritical deformations. These three factors are the shape of initial deformation, the amplitude of geometric imperfection and the slenderness of bars. The analysis was made of bars fixed on both sides for three initial shapes of deformation between adjacent stirrups, four amplitudes of geometric imperfections and eight bar slendernesses. The results of the numerical analyses carried out showed that the factors analysed have a very high influence on the inelastic buckling of the bars. The initial deformation shape, the radius of curvature and the slenderness of the bars have a significant influence on the buckling resistance of these bars and their longitudinal and transverse deformations. The research demonstrates that bars which are bent or compressed initially have a smaller resistance to buckling compared to straight bars, as the amplitude of geometric imperfections increases and the slenderness of the members increases. However, for the deformation shape of the bars, which is accompanied by shear forces, the drop in the buckling resistance of the members is small, and resistance to buckling for items with a small slenderness was higher than that of straight bars.

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Bar buckling in ductile RC walls with different boundary zone detailing: Experimental investigation

Cited by 27 publications

References 38 publications

Experimental study on the effects of bi‐directional loading pattern on rectangular reinforced concrete walls

Experimental study on the effects of bi‐directional loading pattern on rectangular reinforced concrete walls

Designing and detailing transverse reinforcement to control bar buckling in rectangular RC walls

Influence of Geometric Imperfections on Buckling Resistance of Reinforcing Bars during Inelastic Deformation

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