Load carrying capacity of deteriorated reinforced concrete columns

Experimental testing of lightly reinforced concrete column was conducted to investigate the collapse behavior of such column under cyclic lateral loading. Six column specimens, which have low longitudinal reinforcement and lack of confinement, were detailed with no lap splice, and non-ductile lap splice within or outside critical region. Placing the short, unconfined column's lap splice within critical region caused peak moment to fall short under its nominal moment capacity. In contrast, moment capacity of the specimen containing non-ductile lap splice outside critical region was in close agreement with those of specimen without lap splice. However, its inelastic damage region was moving away from the beam-column interface, resulted in degradation of drift capacity and rapid degradation of lateral strength. The presence of non-ductile lap splice outside critical region also potentially shift column's collapse mechanism from flexure to flexure-shear critical. The ability of lightly reinforced concrete columns to maintain its axial load carrying capacity to large drift ratios despite heavy damage and significant loss of lateral load carrying capacity indicates that lap splice failure does not create sudden collapse hazard.

Download Full-text

Structural Behavior of RC Columns Improved by Different Strengthening Techniques

Slovak Journal of Civil Engineering ◽

10.2478/sjce-2020-0020 ◽

2020 ◽

Vol 28 (3) ◽

pp. 20-28

Author(s):

Shah Rukh Tariq ◽

Liaqat Ali Qureshi ◽

Babar Ali ◽

Muhammad Usman Rashid

Keyword(s):

Reinforced Concrete ◽

Carrying Capacity ◽

Concrete Columns ◽

Load Carrying Capacity ◽

Cross Sectional ◽

Rc Columns ◽

Reinforced Concrete Columns ◽

Existing Structures ◽

Axial Capacity ◽

Load Carrying

AbstractDeficient or deteriorating reinforced-concrete columns in many existing structures have to be strengthened using economical, efficient, and fast methods. In the present study, different strengthening techniques to improve the load-carrying capacity of reinforced concrete (RC) columns have been compared. Five groups of fifteen square reinforced concrete columns (150 mm × 150 mm × 600 mm) and one group of three circular columns ( φ 170 mm) that have cross-sectional areas equivalent to those of the square columns were cast from normal-strength concrete. The test program was designed to examine the behavior of columns strengthened by carbon fiber-reinforced polymer (CFRP), steel jacketing, ferro cement, steel fibers, and silica fumes under cyclic axial compression. The efficiency of each strengthening method in increasing the column’s axial capacity, energy absorption, and ductility was studied using the experimental data. The test results showed that strengthening the columns could significantly enhance their load-carrying capacity and failure strains.

Download Full-text

Design of FRP-wrapped reinforced concrete columns for enhancing axial load carrying capacity

Composite Structures ◽

10.1016/j.compstruct.2007.04.002 ◽

2008 ◽

Vol 82 (1) ◽

pp. 132-139 ◽

Cited By ~ 38

Author(s):

Yung-Chih Wang ◽

K. Hsu

Keyword(s):

Reinforced Concrete ◽

Carrying Capacity ◽

Axial Load ◽

Concrete Columns ◽

Load Carrying Capacity ◽

Reinforced Concrete Columns ◽

Load Carrying

Download Full-text

Improvement of Regulatory Calculation of the Load-Carrying Capacity of Vibrated, Centrifuged, and Vibrocentrifuged-Based Iron-Concrete Columns with Variatropic Structure

НАУЧНЫЙ ЖУРНАЛ СТРОИТЕЛЬСТВА И АРХИТЕКТУРЫ ◽

10.36622/vstu.2020.59.3.007 ◽

2020 ◽

pp. 78-84

Author(s):

Л. Р. Маилян ◽

С. А. Стельмах ◽

Е. М. Щербань ◽

А. А. Чернильник

Keyword(s):

Reinforced Concrete ◽

Cross Section ◽

Carrying Capacity ◽

Concrete Columns ◽

Strength Analysis ◽

Load Carrying Capacity ◽

Load Bearing Capacity ◽

Load Carrying ◽

Regulatory Approach ◽

Concrete Elements

Состояние проблемы. Сжатые железобетонные элементы изготавливаются по трем основным технологиям - вибрированием, центрифугированием и виброцентрифугированием. Однако все основные расчетные зависимости для определения их несущей способности выведены, исходя из основного постулата - постоянства и равенства характеристик бетона по сечению, что соответствует действительности лишь в вибрированных колоннах. Результаты. Разработан усовершенствованный нормативный подход к расчету прочности центрифугированных и виброцентрифугированных железобетонных колонн, заключающийся в использовании в расчете интегральных или дифференциальных характеристик бетона. Выводы. Расчет прочности коротких центрально сжатых вибрированных, центрифугированных и виброцентрифугированных колонн по усовершенствованному нормативному подходу дал наилучшие результаты с использованием дифференциальных характеристик бетона, различающихся по сечению. Statement of the problem. Compressed reinforced concrete elements are manufactured according to three main technologies - vibrating, centrifuging and vibrocentrifugation. However, all the main calculated dependences for determining their load-bearing capacity were derived based on the main postulate - the constancy and equality of the characteristics of concrete over the cross section, which corresponds to reality only in vibrated columns. Results. An improved regulatory approach has been developed for calculating the strength of centrifuged and vibrocentrifuged reinforced concrete columns, which involves using the calculation of integral or differential characteristics of concrete. Conclusions. Strength analysis of short centrally compressed vibrated, centrifuged and vibrocentrifuged columns using an improved regulatory approach yielded the best results using differential characteristics of concrete varying in cross section.

Download Full-text

Finite Element Analysis on Reinforced Concrete Columns Strengthened by ECC Jacketing under Eccentric Compressive Load

Engineering Journal ◽

10.4186/ej.2020.24.5.77 ◽

2020 ◽

Vol 24 (5) ◽

pp. 77-91

Author(s):

Mohammad Javad Memar ◽

Ali Kheyroddin ◽

Ali Hemmati

Keyword(s):

Finite Element ◽

Reinforced Concrete ◽

Carrying Capacity ◽

Tensile Strain ◽

Bending Moment ◽

Concrete Columns ◽

Load Carrying Capacity ◽

Normal Concrete ◽

Eccentric Load ◽

Load Carrying

Engineered cementitious composite (ECC) can be used for strengthening of concrete columns due to its similar structure and suitable connection to normal concrete and its special tension behavior. In this study, to analyse the columns, finite element (FE) method was used after verification by experimental results. Reference column was strengthened by normal concrete and ECC jacketing. The effects of type of jacket material, longitudinal reinforcement, compressive stress and ultimate tensile strain of ECC on variations of eccentric load-bending moment (P-M) interaction curves were investigated. Results showed that the use of ECC instead of normal concrete can increase load carrying capacity of strengthened column, due to tensile strain hardening behavior of this material. It was found that, amount of this increase depends on eccentricity of eccentric load and varying from 0.4-23%. In ECC jacketing, tensile cracks are continuous, but in concrete jacketing, there were discrete cracks and more quantity of damages. Due to higher load carrying capacity and better distribution of tensile cracks in ECC jacketing than normal concrete jacketing, the use of ECC is suitable for strengthening of reinforced concrete columns. Load carrying capacity of columns under concentric load and pure bending moment were calculated by theoretical method and the results were compared with FE.

Download Full-text