Boundary Elements of Special Reinforced Concrete Walls Tested under Different Loading Paths

Haro, Ana Gabriela; Kowalsky, Mervyn J.; Chai, Y. H.; Lucier, Gregory

doi:10.1193/081617eqs160m

Cited by 22 publications

(8 citation statements)

References 11 publications

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“…It should be mentioned that the type of restraint at the storey level that allows rotation in the OOP direction as well as the type of strain gradient along the wall height would affect the buckling length. The fully fixed boundary conditions with a strain gradient that is fairly uniform along the height (similar to the one of the isolated boundary zones under tensile-compressive cycles [12]) limits the buckling length to 60% of the unsupported height. However, if there is no restraint provided at the storey level against the rotation in the OOP direction, as was the case in some wall experiments [15], the buckling length would be close to the whole unsupported height of the wall [26].…”

Section: Failure Mechanism and Controlling Parameters Salient Features Of Oop Instabilitymentioning

confidence: 99%

“…The basic findings of these studies were confirmed by Chai and Elayer [5], who investigated the OOP instability of structural walls by testing concrete columns that represented boundary zones of rectangular walls. This method has become a common approach for investigating this mode of failure [6][7][8][9][10][11][12][13]. However, many assumptions need to be made such as: a) the wall region that undergoes the OOP instability, b) the boundary conditions at the top, bottom and along the edge that joins the boundary zone to the central wall panel, and c) the height of the wall involved in the formation of OOP instability.…”

Section: Introductionmentioning

confidence: 99%

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Design recommendations to prevent global out-of-plane instability of rectangular reinforced concrete ductile walls

Dashti

Dhakal

Pampanin

2021

BNZSEE

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Observations of out-of-plane (OOP) instability in the 2010 Chile earthquake and in the 2011 Christchurch earthquake resulted in concerns about the current design provisions of structural walls. This mode of failure was previously observed in the experimental response of some wall specimens subjected to in-plane loading. Therefore, the postulations proposed for prediction of the limit states corresponding to OOP instability of rectangular walls are generally based on stability analysis under in-plane loading only. These approaches address stability of a cracked wall section when subjected to compression, thereby considering the level of residual strain developed in the reinforcement as the parameter that prevents timely crack closure of the wall section and induces stability failure. The New Zealand code requirements addressing the OOP instability of structural walls are based on the assumptions used in the literature and the analytical methods proposed for mathematical determination of the critical strain values. In this study, a parametric study is conducted using a numerical model capable of simulating OOP instability of rectangular walls to evaluate sensitivity of the OOP response of rectangular walls to variation of different parameters identified to be governing this failure mechanism. The effects of wall slenderness (unsupported height-to-thickness) ratio, longitudinal reinforcement ratio of the boundary regions and length on the OOP response of walls are evaluated. A clear trend was observed regarding the influence of these parameters on the initiation of OOP displacement, based on which simple equations are proposed for prediction of OOP instability in rectangular walls.

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Section: Failure Mechanism and Controlling Parameters Salient Features Of Oop Instabilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Design recommendations to prevent global out-of-plane instability of rectangular reinforced concrete ductile walls

Dashti

Dhakal

Pampanin

2021

BNZSEE

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“…It has been observed that such type of failure is so critical that can lead to partial or total collapses of multi-storey reinforced concrete buildings [37]. This phenomenon can appear when the boundary edges of seismic walls have sustained a large size of tensile loading during the first semi-cycle of seismic loading and then are subjected to a compressive loading during the second semi-cycle of earthquake loading [38]- [41]. Transverse buckling appears when the cracks formed during the first stage of tensile loading have such a large width that makes it impossible to be closed during the second stage of compressive loading [42]- [51].…”

Section: Introductionmentioning

confidence: 99%

Analytical Investigation of the Tensile Experiments Modeling the Elongation Degree of R/C Walls for Studying the Lateral Buckling Phenomenon

Chrysanidis¹,

Panoskaltsis²

2021

Proceedings of the 8th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

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In the context of the present work, the influence of the degree of tension on the phenomenon of transverse instability of reinforced concrete walls is examined. The present investigation is basically analytical but it contains experimental results of 4 test specimens published from the first author in the past. These specimens simulate the extreme boundary edges of structural walls. All columns simulate only the extreme reinforced areas of the walls, in order to study the basic mechanism of the phenomenon. The detailing of the specimens consists of 4 rebars with a diameter of 8 mm for each bar. The geometric dimensions are the same for all specimens. What differentiates the specimens from each other is the degree of tension they have sustained. More specifically, the tensile degrees used are 10‰, 20‰, 30‰, 50‰. The loading stages of each specimen for all specimens are as follows: (a) Uniaxial central tensile loading on each test specimen, (b) Uniaxial central compression loading on each specimen till its failure due to buckling or due to an excess of its cross-section compressive strength. The present study focuses on the tensile loading stage only. Extreme tensile strains are also used, e.g., 30‰ and 50‰, to take into account the cases of extreme seismic excitations. First, the experimental results from a previous publication are presented and afterwards they are followed by the numerical investigation of these 4 specimens using appropriate finite element software. Useful conclusions are drawn regarding the precision of the experimental tests investigating the influence of the degree of elongation on the phenomenon of transverse buckling. These conclusions are substantiated both experimentally and analytically, as the results of the tensile experiments are compared with the corresponding results of the analytical investigation.

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“…While this type of failure had been previously reported experimentally (Goodsir, 1985;Oesterle et al, 1976;Thomsen and Wallace, 2004), this was the first time it had been widely observed after earthquake events. Correspondingly, there has recently been a great deal of experimental and numerical investigative research focusing on the out-of-plane instability of RC walls due to in-plane loading (Dashti et al, 2018;Haro et al, 2018;Parra and Moehle, 2017;Rosso et al, 2016;Rosso et al, 2018). However, all of these recently tested specimens were either planar (i.e., rectangular) walls or idealized boundary elements.…”

Section: Introductionmentioning

confidence: 99%

Seismic performance of slender RC U-shaped walls with a single-layer of reinforcement

Hoult

Appelle

Almeida

et al. 2020

Engineering Structures

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Reinforced concrete walls are commonly used to resist the lateral loading induced by wind and earthquake actions. While most walls include two vertical reinforcement layers, some regions of the world construct slender, non-rectangular concrete walls with a single vertical layer of reinforcement. The seismic performance of such elements is largely unknown given the paucity of experimental research. This paper presents the results of two slender reinforced concrete U-shaped walls tested at the Earthquake Engineering and Structural Dynamics Laboratory (EESD Lab), École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland. Both wall specimens, designed similar to construction practice in Colombia, were tested using quasi-static cyclic loading to observe if out-of-plane instability would develop when deformations were limited to prevent the flange boundary ends crushing. Initial failure of both wall specimens corresponded with local out-of-plane buckling in the boundary ends of the flanges occurring on load reversal. The buckling lengths were approximately 700-800 mm, which corresponded to 44-50 bar diameters. The crack patterns were observed to be steepest in the web of the walls, demonstrating the increased shear demand in comparison to that of a rectangular wall. Both wall specimens reached ultimate drifts larger than 2.5-3.0% before global failure occurring in the web-flange intersection due to crushing. A small twist was subjected to one of the walls when centered and loaded diagonally, which showed that the decay in torsional stiffness is proportional to the decay in translational stiffness.

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Boundary Elements of Special Reinforced Concrete Walls Tested under Different Loading Paths

Cited by 22 publications

References 11 publications

Design recommendations to prevent global out-of-plane instability of rectangular reinforced concrete ductile walls

Design recommendations to prevent global out-of-plane instability of rectangular reinforced concrete ductile walls

Analytical Investigation of the Tensile Experiments Modeling the Elongation Degree of R/C Walls for Studying the Lateral Buckling Phenomenon

Seismic performance of slender RC U-shaped walls with a single-layer of reinforcement

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