Drift performance of lightly reinforced concrete columns

Wibowo, Ari; Wilson, John L.; Lam, Nelson; Gad, Emad

doi:10.1016/j.engstruct.2013.11.016

Cited by 34 publications

(23 citation statements)

References 10 publications

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“…However, from a collapse prevention perspective in regions of lower seismicity, an alternative definition is associated with the drift at which the gravity axial load can no longer be maintained. The failure drifts associated with these definitions are similar for walls and columns with high axial load ratios, but for lightly loaded elements typical of many structural walls, the drift at lateral load failure is considerably smaller than the drift at axial load failure (Wibowo et al, 2014). (c) The authors agree that the term effective wall height is a better term to use rather than the wall height, particularly for different wall test loading configurations.…”

mentioning

confidence: 66%

Discussion: Seismic performance of lightly reinforced structural walls for design purposes

Wibowo¹,

Wilson²,

Lam³

et al. 2014

Magazine of Concrete Research

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The paper on the seismic performance of lightly reinforced concrete walls by Wibowo et al. (2013) is both interesting and timely, but several points require clarification.The authors defined lightly reinforced structural walls as having a total vertical reinforcement ratio between 0 . 2% and 2%. However, the lateral load behaviour of concrete walls within this range would vary substantially. A single flexural crack may form in a wall with 0 . 2% vertical reinforcement, whereas a wall with 2% vertical reinforcement would be expected to form a ductile plastic hinge with a large number of well-distributed cracks. The range of vertical reinforcement ratios may be too large to develop a suitable analytical model to represent the range of expected behaviour.The typology of walls included in the literature review is not well defined and this may explain the large scatter of results that can be observed in Figure 1. For example, the walls tested by Gebreyohaness et al. were intended to represent walls in a building constructed in 1936 that were identified as having several deficiencies including the use of plain vertical reinforcement and inadequate splices (Gebreyohaness et al., 2011) The experimental results of Gebreyohaness' walls cannot be compared against walls with ductile detailing that satisfy modern design standards. Additionally, walls WPS5, WPS7 and WPS8 were reported as having an ultimate drift capacity of 3 . 5%. The strength of these walls at 3 . 5% drift had degraded significantly to less than 50% of the maximum strength, with either the splice or vertical reinforcement having failed at lower drifts. The ultimate drift is often defined as occurring when the strength drops below 80% of the maximum strength (Park, 1989) and the definition of ultimate drift should be clarified.In Table 3, the aspect ratios of the walls would be better represented as H e /L w or M/VL w (where H e is the effective wall height) rather than H w /L w : For the test setup used by Greifenhagen and Lestuzzi (2005) and Thomsen and Wallace (2004), the loading point was not at the top of the wall and the loading height is not included in Table 3.In Table 3, the vertical reinforcement ratios reported for the two walls by Thomsen and Wallace (2004) are incorrect. The correct total vertical reinforcement ratios of RW1 and RW2 should be 1 . 1%, which is much higher than 0 . 17% stated in Table 3. The authors also incorrectly stated that, because of the low vertical reinforcement in these two specimens, flexure behaviour was dominated by a single crack at the base of the wall (Wibowo et al., 2013: p. 821). The observed test results reported by Thomsen and Wallace (2004) did not indicate a single flexural crack, and wall failure was controlled by buckling of the vertical reinforcement in the boundary elements.It is unclear why the authors have elected to follow different procedures for the detailed and simplified models. For example, in the simplified model, behaviour is assumed to be dominated by either single or multiple flexural cracks b...

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mentioning

confidence: 66%

Discussion: Seismic performance of lightly reinforced structural walls for design purposes

Wibowo¹,

Wilson²,

Lam³

et al. 2014

Magazine of Concrete Research

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“…It is noteworthy that the longitudinal reinforcement ratio divided by the ratio of the confined to the total cross‐section area gives a better prediction than the unnormalised ratio, the latter being more common a variable in pre‐peak models. This can be attributed to the fact that after the critical shear crack has formed at the onset of shear degradation, the effective concrete area is the confined one, as the unconfined cover concrete either has already spalled off within the member critical length or it does not actively contribute as resistance mechanism, due to substantial reduction in its strength. Higher transverse reinforcement is beneficial, as expected; the transverse steel bars crossing the critical crack are one of the main shear resistance mechanisms. The average diameter of longitudinal bars over the effective depth, Φ l,ave / d , seems to play an important role, too, decreasing the degradation rate as it increases. Aspect ratio was investigated, as it was considered important in a previous model, but was found not to hold very high predictive strength. This is attributed to the fact that the localisation of shear strains in the critical length was considered, hence eliminating the effect of aspect ratio, which is pronounced when taking into account the inter‐storey drift ratio and disregarding shear failure localisation.…”

Section: Calibration Of Hysteretic Shear Model Parameters In the Critmentioning

confidence: 86%

“…• The average diameter of longitudinal bars over the effective depth, Φ l,ave /d, seems to play an important role, too, decreasing the degradation rate as it increases. • Aspect ratio was investigated, as it was considered important in a previous model, 41 but was found not to hold very high predictive strength. This is attributed to the fact that the localisation of shear strains in the critical length was considered, hence eliminating the effect of aspect ratio, which is pronounced when taking into account the inter-storey drift ratio and disregarding shear failure localisation.…”

Section: Descending Branchmentioning

confidence: 99%

Modelling of R/C members accounting for shear failure localisation: Hysteretic shear model

Zimos

Mergos

Kappos

2018

Earthq Engng Struct Dyn

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Summary Reinforced concrete (R/C) frame buildings designed according to older seismic codes represent a large part of the existing building stock worldwide. Their structural elements are often vulnerable to shear or flexure‐shear failure, which can eventually lead to loss of axial load resistance of vertical elements and initiate vertical progressive collapse of a building. In this study, a hysteretic model capturing the local shear response of shear‐deficient R/C elements is described in detail, with emphasis on post‐peak behaviour; it differs from existing models in that it considers the localisation of shear strains after the onset of shear failure in a critical length defined by the diagonal failure planes. Additionally, an effort is made to improve the state of the art in post‐peak shear response modelling, by compiling the largest database of experimental results for shear and flexure‐shear critical R/C columns cycled well beyond the onset of shear failure and/or up to the onset of axial failure, and developing empirical relationships for the key parameters defining the local backbone post‐peak shear response of such elements. The implementation of the derived local hysteretic shear model in a computationally efficient beam‐column finite element model with distributed shear flexibility, which accounts for all deformation types, will be presented in a companion paper.

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“…These are large drifts for a limited-ductility column, but effective of the relatively low axial loads applied to the column. More information on the influence of axial load on the ultimate drift capacity of limited-ductility RC columns have been discussed in Wibowo et al [18].…”

Section: Quasi-static Cyclic Testmentioning

confidence: 99%

Collapse Assessment of Reinforced Concrete Building Columns through Multi-Axis Hybrid Simulation

Hashemi

Tsang

Al-Ogaidi

et al. 2017

ACI Structural Journal

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Drift performance of lightly reinforced concrete columns

Cited by 34 publications

References 10 publications

Discussion: Seismic performance of lightly reinforced structural walls for design purposes

Discussion: Seismic performance of lightly reinforced structural walls for design purposes

Modelling of R/C members accounting for shear failure localisation: Hysteretic shear model

Collapse Assessment of Reinforced Concrete Building Columns through Multi-Axis Hybrid Simulation

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