scholarly journals Analytical Review on Eccentric Axial Compression Behavior of Short and Slender Circular RC Columns Strengthened Using CFRP

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2763
Author(s):  
Muhammad Abid ◽  
Haytham F. Isleem ◽  
Muhammad Kamal Kamal Shah ◽  
Shayan Zeb
Keyword(s):  
Reinforced Concrete ◽  
Axial Compression ◽  
Slenderness Ratio ◽  
Concrete Columns ◽  
Practice Research ◽  
Small Scale ◽  
Stress Strain ◽  
Eccentric Load ◽  
Rc Columns ◽  
Proposed Model

Although reinforced concrete (RC) columns subjected to combined axial compression and flexural loads (i.e., eccentric load) are the most common structural members used in practice, research on FRP-confined circular RC columns subjected to eccentric axial compression has been very limited. More specifically, the available eccentric-loading models were mainly based on existing concentric stress–strain models of FRP-confined unreinforced concrete columns of small scale. The strength and ductility of FRP-strengthened slender circular RC columns predicted using these models showed significant errors. In light of such demand to date, this paper presents a stress–strain model for FRP-confined circular reinforced concrete (RC) columns under eccentric axial compression. The model is mainly based on observations of tests and results reported in the technical literature, in which 207 results of FRP-confined circular unreinforced and reinforced concrete columns were carefully studied and analyzed. A model for the axial-flexural interaction of FRP-confined concrete is also provided. Based on a full parametric analysis, a simple formula of the slenderness limit for FRP-strengthened RC columns is further provided. The proposed model considers the effects of key parameters such as longitudinal and hoop steel reinforcement, level of FRP hoop confinement, slenderness ratio, presence of longitudinal FRP wraps, and varying eccentricity ratio. The accuracy of the proposed model is finally validated through comparisons made between the predictions and the compiled test results.

scholarly journals Axial Compressive Strength Models of Eccentrically-Loaded Rectangular Reinforced Concrete Columns Confined with FRP

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3498
Author(s):  
Haytham F. Isleem ◽  
Muhammad Abid ◽  
Wesam Salah Alaloul ◽  
Muhammad Kamal Shah ◽  
Shayan Zeb ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Large Scale ◽  
Concrete Strength ◽  
Concrete Columns ◽  
Confined Concrete ◽  
Practice Research ◽  
Small Scale ◽  
Technical Literature ◽  
Rc Columns ◽  
Strength Models

The majority of experimental and analytical studies on fiber-reinforced polymer (FRP) confined concrete has largely concentrated on plain (unreinforced) small-scale concrete columns, on which the efficiency of strengthening is much higher compared with large-scale columns. Although reinforced concrete (RC) columns subjected to combined axial compression and flexural loads (i.e., eccentric compression) are the most common structural elements used in practice, research on eccentrically-loaded FRP-confined rectangular RC columns has been much more limited. More specifically, the limited research has generally been concerned with small-scale RC columns, and hence, the proposed eccentric-loading stress-strain models were mainly based on the existing concentric-loading models of FRP-confined concrete columns of small scale. In the light of such demand to date, this paper is aimed at developing a mathematical model to better predict the strength of FRP-confined rectangular RC columns. The strain distribution of FRP around the circumference of the rectangular sections was investigated to propose equations for the actual rupture strain of FRP wrapped in the horizontal and vertical directions. The model was accomplished using 230 results of 155 tested specimens compiled from 19 studies available in the technical literature. The test database covers an unconfined concrete strength ranging between 9.9 and 73.1 MPa, and section’s dimension ranging from 100–300 mm and 125–435 mm for the short and long sides, respectively. Other test parameters, such as aspect ratio, corner radius, internal hoop steel reinforcement, FRP wrapping layout, and number of FRP wraps were all considered in the model. The performance of the model shows a very good correlation with the test results.

Axial Compression Capacity of Shear-Damaged Reinforced Concrete Columns and Lashing Belt Prestressing

2016 ◽  
Vol 711 ◽  
pp. 1012-1018
Author(s):  
Kozo Nakada ◽  
Kochi Masaaki ◽  
Yu Yun Dong ◽  
Long Yu
Keyword(s):  
Reinforced Concrete ◽  
Axial Compression ◽  
Concrete Columns ◽  
Hysteretic Behavior ◽  
Load Carrying Capacity ◽  
Vertical Load ◽  
Shear Strengthening ◽  
Rc Columns ◽  
Load Carrying ◽  
Strength And Ductility

The compressive strength and ductility of concrete can be considerably improved by lateral confinement. In this study, an emergency seismic retrofit technique using lashing belt prestressing is used as to manually retrofit damaged reinforced concrete (RC) columns. The initial prestressing is an important aspect of this technique and is introduced by the ratchet buckle. Thus, this technique offers active and passive confinement as well as shear strengthening. Furthermore, diagonal cracks in the damaged RC columns can be closed by using the active confinement of lashing belts, and the lateral and vertical load-carrying capacity and ductility of the damaged RC columns are recovered. In this study, the recovered axial compression capacity of the retrofitted RC columns and repaired RC columns using epoxy resin was investigated. Finally, the hysteretic behavior of the shear-damaged RC columns after the proposed emergency retrofit was investigated.

scholarly journals Strengthening of Low-Strength Concrete Columns with Fibre Reinforced Polymers. Full-Scale Tests

2020 ◽  
Vol 5 (11) ◽  
pp. 91
Author(s):  
Sonia Martínez ◽  
Ana de Diego ◽  
Viviana J. Castro ◽  
Luis Echevarría ◽  
Francisco J. Barroso ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Concrete Columns ◽  
Experimental Program ◽  
Small Scale ◽  
Rc Columns ◽  
Reinforced Polymers ◽  
Strain Capacity ◽  
Strength Concrete ◽  
Low Strength ◽  
Low Strength Concrete

Confinement of columns with externally bonded fibre reinforced polymers (FRP) sheets is an easy and effective way of enhancing the load carrying and strain capacity of reinforced concrete (RC) columns. Many experimental studies have been conducted on cylindrical small-scale un-reinforced concrete specimens externally confined with FRP. It is widely accepted that confinement of square or rectangular columns is less efficient than the confinement of circular columns. The theoretical models for rectangular sections are mostly based on approaches for circular columns modified by a shape factor, but the different models do not give similar results. This paper presents an experimental program on large-scale square and rectangular RC columns externally strengthened with carbon FRP sheets and subjected to axial load. The main variables were the side-aspect ratio of the cross-section, the radius of curvature of the corners and the amount of FRP reinforcement. The results show that the FRP confinement can increase the strength and strain capacity of rectangular concrete columns with low strength concrete. The FRP hoop ultimate strain was much lower than the material ultimate tensile strain obtained from flat coupon tests and the strain efficiency factor achieved in the tests was less than the value usually recommended by design guides.

Experimental Investigation of Reinforced Concrete Columns with Steel Embedded Tubes

2021 ◽  
Vol 878 ◽  
pp. 134-143
Author(s):  
Mohammed H. Hameed ◽  
Ali Hussein Ali Al-Ahmed ◽  
Zena K. Abbas
Keyword(s):  
Experimental Investigation ◽  
Reinforced Concrete ◽  
Cross Section ◽  
Concrete Columns ◽  
Experimental Results ◽  
Experimental Program ◽  
Test Results ◽  
Steel Tubes ◽  
Eccentric Load ◽  
Rc Columns

This study aimed to investigate the influence of longitudinal steel embedded tubes located at the center of the column cross-section on the behavior of reinforced concrete (RC) columns. The experimental program consisted of 8 testing pin-ended square sectional columns of 150×150 mm, having a total height of 1400 mm, subjected to eccentric load. The considered variables were the steel square tube sizes of 25, 51 and 68 mm side dimensions and the load eccentricity (50 and 150) mm. RC columns were concealed steel tubes with hollow ratios of 3%, 12% and 20% depending on tube sizes used. The experimental results indicated an improvement in the overall behavior of eccentric columns when steel embedded tubes are used. The maximum gain in strength was about 59% for the hollow ratio of 20% with e/h=1. The test results show that the inserted steel pipe improves strength, ductility and enables these columns to absorb more energy than a similar solid column.

Seismic assessment of reinforced concrete columns with short lap splices

2021 ◽  
pp. 875529302199483
Author(s):  
Eyitayo A Opabola ◽  
Kenneth J Elwood
Keyword(s):  
Reinforced Concrete ◽  
Failure Mode ◽  
Failure Modes ◽  
Concrete Columns ◽  
Seismic Assessment ◽  
Rc Columns ◽  
Lap Splices ◽  
Displacement Response ◽  
Force Displacement ◽  
Probable Failure

Existing reinforced concrete (RC) columns with short splices in older-type frame structures are prone to either a shear or bond mechanism. Experimental results have shown that the force–displacement response of columns exhibiting these failure modes are different from flexure-critical columns and typically have lower deformation capacity. This article presents a failure mode-based approach for seismic assessment of RC columns with short splices. In this approach, first, the probable failure mode of the component is evaluated. Subsequently, based on the failure mode, the force–displacement response of the component can be predicted. In this article, recommendations are proposed for evaluating the probable failure mode, elastic rotation, drift at lateral failure, and drift at axial failure for columns with short splices experiencing shear, flexure, or bond failures.

A combined experimental and numerical analysis on the seismic behavior of short reinforced concrete columns with different structural sizes and axial compression ratios

2017 ◽  
Vol 27 (9) ◽  
pp. 1416-1447 ◽  
Author(s):  
Liu Jin ◽  
Shuai Zhang ◽  
Dong Li ◽  
Haibin Xu ◽  
Xiuli Du ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Axial Compression ◽  
Seismic Behavior ◽  
Load Capacity ◽  
Concrete Columns ◽  
Simulation Method ◽  
Reinforced Concrete Columns ◽  
Mesoscopic Simulation ◽  
Energy Dissipation Capacity

The results of an experimental program on eight short reinforced concrete columns having different structural sizes and axial compression ratios subjected to monotonic/cyclic lateral loading were reported. A 3D mesoscopic simulation method for the analysis of mechanical properties of reinforced concrete members was established, and then it was utilized as an important supplement and extension of the traditional experimental method. Lots of numerical trials, based on the restricted experimental results and the proposed 3D mesoscopic simulation method, were carried out to sufficiently evaluate the seismic performances of short reinforced concrete columns with different structural sizes and axial compression ratios. The test results indicate that (1) the failure pattern of reinforced concrete columns can be significantly affected by the shear-span ratio; (2) increasing the axial compression ratio could improve the load capacity of the reinforced concrete column, but the deformation capacity would be restricted and the failure mode would be more brittle, consequently the energy dissipation capacity could be deteriorated; and (3) the load capacity, the displacement ductility, and the energy dissipation capacity of the short reinforced concrete columns all exhibit clear size effect, namely, the size effect could significantly affect the seismic behavior of reinforced concrete columns.

Study on the Behaviors of Steel Reinforced Concrete Cloumns

2011 ◽  
Vol 368-373 ◽  
pp. 248-252
Author(s):  
Bao Sheng Yang ◽  
Yun Yun Li
Keyword(s):  
Bearing Capacity ◽  
Axial Compression ◽  
Compression Ratio ◽  
High Strength Concrete ◽  
Seismic Behavior ◽  
Slenderness Ratio ◽  
High Strength ◽  
Concrete Columns ◽  
Axial Compression Ratio ◽  
High Strength Concrete Columns

The influence on columns behaviors of slenderness ratio are analyzed, and the influence on columns’ anti-seismic behavior of axial compression ratio, stirrup ratio and steel form are analyzed through the test on bearing capacity and level load of low cycle reverse of steel reinforced high-strength concrete columns. The bearing capacity of the long columns reduces along with the slenderness ratio increasing and augments along with concrete strength increasing. Probability of suddenly destruct increases along with the column slenderness ratio augmenting through the test. In addition, anti-seismic behavior of columns are effected not only axial compression ratio, but also steel form. Axial compression coefficien of the steel reinforced high-strength concrete columns with different steel form may be adjusted, however, the influence of stirrup ratio is very little on anti-seismic behavior of columns.

Analytical stress–strain model of reinforced concrete masonry wallettes under axial compression

Structures ◽  
2021 ◽  
Vol 34 ◽  
pp. 2922-2935
Author(s):  
Tatheer Zahra ◽  
Julian Thamboo ◽  
Mohammad Asad ◽  
Mengli Song
Keyword(s):  
Reinforced Concrete ◽  
Axial Compression ◽  
Stress Strain ◽  
Concrete Masonry ◽  
Strain Model
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