Modelling failures in existing reinforced concrete columns

2004 ◽  
Vol 31 (5) ◽  
pp. 846-859 ◽  
Author(s):  
Kenneth J Elwood
Keyword(s):  
Reinforced Concrete ◽  
Shear Failure ◽  
Concrete Columns ◽  
Failure Surface ◽  
Material Model ◽  
Transverse Reinforcement ◽  
Reinforced Concrete Columns ◽  
In Series ◽  
Column Element ◽  
Axial Failure

Experimental research and post-earthquake reconnaissance have demonstrated that reinforced concrete columns with light or widely spaced transverse reinforcement are vulnerable to shear failure, and in turn, axial failure during earthquakes. Based on experimental data, failure surfaces have been used to define the onset of shear and axial failure for such columns. After the response of the column intersects the failure surface, the shear or axial strength of the column begins to degrade. This paper introduces a uniaxial material model that incorporates the failure surfaces and the subsequent strength degradation. When used in series with a beam-column element, the uniaxial material model can adequately capture the response of reinforced concrete columns during shear and axial load failure. The performance of the analytical model is compared with results from shake table tests.Key words: shear failure, axial failure, beam-column elements, failure surface, earthquakes, reinforced concrete, columns, collapse, structural analysis.

Drift Capacity of Reinforced Concrete Columns with Light Transverse Reinforcement

2005 ◽  
Vol 21 (1) ◽  
pp. 71-89 ◽  
Author(s):  
Kenneth J. Elwood ◽  
Jack P. Moehle
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Shear Failure ◽  
Concrete Columns ◽  
Critical Parameters ◽  
Transverse Reinforcement ◽  
Reinforced Concrete Columns ◽  
Drift Capacity ◽  
Interstory Drift ◽  
Capacity Model

Existing reinforced concrete columns with light transverse reinforcement are vulnerable to shear failure during seismic response. Shear strength models, modeling the degradation of shear strength with increasing displacement ductility demand, have been widely used to evaluate the interstory drift capacity of such columns. The application of a shear strength model to determine the drift capacities for a database of 50 shear-critical columns demonstrates significant inaccuracies with such a method. An empirical drift capacity model based on the shear-critical column database provides a better estimate of the interstory drift at shear failure. The new drift capacity model identifies the most critical parameters affecting the drift capacity of shear-critical columns, namely, transverse reinforcement ratio, shear stress demand, and axial load ratio.

scholarly journals Size Effect on the Seismic Performance of High-Strength Reinforced Concrete Columns with Different Shear Span-to-Depth Ratios

2018 ◽  
Vol 2018 ◽  
pp. 1-19
Author(s):  
Chunyi Yu ◽  
Hua Ma ◽  
Yongping Xie ◽  
Zhenbao Li ◽  
Zhenyun Tang
Keyword(s):  
Reinforced Concrete ◽  
Size Effect ◽  
Seismic Performance ◽  
Factor Of Safety ◽  
Shear Failure ◽  
High Strength ◽  
Concrete Columns ◽  
Reinforced Concrete Columns ◽  
Local Factor ◽  
Shear Span

The size effect on the seismic performance of conventional reinforced concrete columns has been observed in terms of flexural failure and shear failure. Under earthquake loading, slender columns experience flexural failure, and short columns experience flexure-shear failure and shear failure. However, the effect of section size on the seismic performance of high-strength reinforced concrete columns under the conditions of different shear span-to-depth ratios requires further confirmation. For this purpose, six high-strength reinforced concrete columns with shear span-to-depth ratios of 2 and 4 were subjected to cyclic loading in this study. The experimental results indicated that relative nominal flexural strength, energy dissipation coefficient, factor of safety, and local factor of safety all exhibited a strong size effect by decreasing with increasing column size. Furthermore, the size effect became stronger as the shear span-to-depth ratio was increased, except for average energy dissipation coefficient. The observed changes in the factor of safety were in good agreement with the Type 2 size effect model proposed by Bažant. Thus, based on the local factor of safety and Bažant’s Type 2 model, the code equation for moment capacity of different shear span-to-depth ratios was modified to provide a consistent factor of safety regardless of column size.

scholarly journals Transverse Reinforcement in Reinforced Concrete Columns

2013 ◽  
Vol 8 (2) ◽  
pp. 41-50
Author(s):  
Štefan Gramblička ◽  
Peter Veróny
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Concrete Columns ◽  
Transverse Reinforcement ◽  
Transverse Deformation ◽  
Reinforced Concrete Columns

Abstract In the article we are dealing with the influence of transverse reinforcement to the resistance of a cross-section of the reinforced concrete columns and also with the effective detailing of the column reinforcement. We are verifying the correctness of design guides for detailing of transverse reinforcement. We are also taking into account the diameter of stirrups and its influence over transverse deformation of column.

Model for the Lateral Behavior of Reinforced Concrete Columns Including Shear Deformations

2008 ◽  
Vol 24 (2) ◽  
pp. 493-511 ◽  
Author(s):  
Eric J. Setzler ◽  
Halil Sezen
Keyword(s):  
Reinforced Concrete ◽  
Shear Failure ◽  
Experimental Studies ◽  
Concrete Columns ◽  
Shear Capacity ◽  
Lateral Loads ◽  
Reinforced Concrete Columns ◽  
Flexural Response ◽  
Capacity Model ◽  
Lateral Behavior

This research is focused on modeling the behavior of reinforced concrete columns subjected to lateral loads. Deformations due to flexure, reinforcement slip, and shear are modeled individually using existing and new models. Columns are classified into five categories based on a comparison of their predicted shear and flexural strengths, and rules for combining the three deformation components are established based on the expected behavior of columns in each category. Shear failure in columns initially dominated by flexural response is considered through the use of a shear capacity model. The proposed model was tested on 37 columns from various experimental studies. In general, the model predicted the lateral deformation response envelope reasonably well.

scholarly journals The use of Grade 380 steel for transverse confining reinforcement in columns

1987 ◽  
Vol 20 (2) ◽  
pp. 99-115
Author(s):  
F. A. Zahn ◽  
R. Park ◽  
M. J. N. Priestley
Keyword(s):  
Reinforced Concrete ◽  
Axial Load ◽  
Analytical Study ◽  
Concrete Columns ◽  
Lateral Loading ◽  
Transverse Reinforcement ◽  
Reinforced Concrete Columns ◽  
Ductility Factor ◽  
Strain Behaviour ◽  
Curvature Ductility

The results of recent experimental and analytical studies of the stress-strain behaviour of concrete confined by New Zealand manufactured Grade 275 or Grade 380 reinforcing steel are presented. First, the behaviour of three pairs of concentrically loaded reinforced concrete columns containing spirals from either Grade
275 or Grade 380 steel are compared, including the stage at which spiral fracture occurred. Second, the results of tests on four reinforced concrete columns containing Grade 380 spiral or rectangular hoop reinforcement and subjected to combined axial
load and cyclic lateral loading are reported. An analytical
study which was conducted to determine the available curvature ductility factor at the stage of fracture of the transverse reinforcement is described. The results are used to give a guideline for the safe use of Grade 380 steel as transverse confining reinforcement.

scholarly journals Shear Strength Model for Reinforced Concrete Columns with Low Transverse Reinforcement Ratios

2014 ◽  
Vol 17 (10) ◽  
pp. 1373-1385 ◽  
Author(s):  
Cao Thanh Ngoc Tran ◽  
Bing Li
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Axial Load ◽  
Concrete Columns ◽  
Transverse Reinforcement ◽  
Reinforced Concrete Column ◽  
Reinforced Concrete Columns ◽  
Existing Structures ◽  
Reversed Cyclic ◽  
Constant Axial Load

This paper introduces an equation developed based on the strut-and-tie analogy to predict the shear strength of reinforced concrete columns with low transverse reinforcement ratios. The validity and applicability of the proposed equation are evaluated by comparison with available experimental data. The proposed equation includes the contributions from concrete and transverse reinforcement through the truss action, and axial load through the strut action. A reinforced concrete column with a low transverse reinforcement ratio, commonly found in existing structures in Singapore and other parts of the world was tested to validate the assumptions made during the development of the proposed equation. The column specimen was tested to failure under the combination of a constant axial load of 0.30 f' c A g and quasi-static cyclic loadings to simulate earthquake actions. The analytical results revealed that the proposed equation is capable of predicting the shear strength of reinforced concrete columns with low transverse reinforcement ratios subjected to reversed cyclic loadings to a satisfactory level of accuracy

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