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.

scholarly journals Experimental Investigation on Short Concrete Columns Reinforced by Bamboo Scrimber under Axial Compression Loads

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Min Lei ◽  
Zihao Wang ◽  
Penghui Li ◽  
Liyi Zeng ◽  
Hongyao Liu ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Axial Compression ◽  
Concrete Columns ◽  
Steel Reinforcement ◽  
Concrete Column ◽  
Strength Concrete ◽  
Bamboo Scrimber ◽  
Low Strength ◽  
Low Strength Concrete

The paper presents bamboo scrimber bars as a reinforcing material instead of steel reinforcement in low-strength concrete columns. Twelve short concrete columns with different reinforcements are tested under axial compression load to study the axial compressive behavior of short concrete columns reinforced by bamboo scrimber. Three columns are reinforced concrete columns, and the other nine columns are bamboo scrimber reinforced concrete columns. The failure process, bearing capacity, axial deformation, and strain of the specimens are compared and analyzed. The results show that the bonding performance between the bamboo scrimber bars by surface treatment and low-strength concrete is excellent. In low-strength concrete columns, the material properties of bamboo bars play more thoroughly than those of steel bars. When the bamboo reinforcement ratio is increased, the concrete column ductility is significantly improved, but the bearing capacity of the concrete column is not increased. The bamboo scrimber bars with the size of 10 mm × 10 mm or 15 mm × 15 mm can be used as longitudinal bars of low-strength concrete columns. The ductility of the short concrete column with 2.56% bamboo scrimber reinforcement is close to that of the short concrete column with 0.72% steel reinforcement.

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 Behavior of Square RC Short Columns with New Arrangement of Ties Subjected to Axial Load: Experimental and Numerical Studies

2022 ◽  
Author(s):  
Hazem Elbakry ◽  
Tarek Ebeido ◽  
El-Tony M. El-Tony ◽  
Momen Ali
Keyword(s):  
Reinforced Concrete ◽  
Axial Load ◽  
Concrete Columns ◽  
Experimental Program ◽  
Transverse Reinforcement ◽  
Reinforcing Bars ◽  
Rc Columns ◽  
Reinforced Concrete Columns ◽  
Short Columns ◽  
Numerical Studies

Reinforced concrete columns consume large quantities of ties, especially inner cross-ties in columns with large dimensions. In some cases, nesting of the pillars occurs as a result of the presence of cross-ties. The main objective of this paper is to develop new methods for transverse reinforcement in RC columns and investigate their effect on the behavior of the columns. The proposed V-ties as transverse reinforcement replacing the ordinary and cross-ties details are economically feasible. They facilitate shorter construction periods and decrease materials and labor costs. For this purpose, experimental and numerical studies are carried out. In the experimental program, nine reinforced concrete columns with identical concrete dimensions and longitudinal reinforcing bars were prepared and tested under concentric axial load with different tie configurations. The main parameters were the tie configurations and the length (lv) of V-tie legs. As part of the numerical study, the finite element model using the ABAQUS software program obtained good agreement with the experimental results of specimens. A numerical parametric study was carried out to study the influence of concrete compressive strength and longitudinal reinforcement ratio on the behavior of RC columns with the considered tie configurations. Based on the experimental and numerical results, it was found that using V-tie techniques instead of traditional ties could increase the axial load capacity of columns, restrain early local buckling of the longitudinal reinforcing bars and improve the concrete core confinement of reinforced concrete columns.

scholarly journals Near-field explosion effects on reinforced concrete columns: an experimental investigation

2018 ◽  
Vol 45 (4) ◽  
pp. 289-303 ◽  
Author(s):  
Abass Braimah ◽  
Farouk Siba
Keyword(s):  
Reinforced Concrete ◽  
Experimental Testing ◽  
Near Field ◽  
Axial Loading ◽  
Concrete Columns ◽  
Load Level ◽  
Experimental Program ◽  
Rc Columns ◽  
Reinforced Concrete Columns ◽  
Scaled Distance

Explosion effects on structures have been an area of active research over the past decades. This is due to the increasing number of terrorists’ action against infrastructures. Although significant amount of work is continuing on the effects of explosions on infrastructures, experimental work involving live explosion testing is limited. Moreover, experimental testing of reinforced concrete (RC) columns subjected to near-field explosions is scant. This paper presents results of an experimental program designed to investigate the effects of near-field explosions on RC columns with different tie spacing and at different scaled distances. The results show that the response of columns is strongly dependent on scaled distance. As the scaled distance increased the severity of damage reduced; seismic columns showed better response. The effect of axial loading was also observed to increase the level of damage on reinforced concrete columns at the axial load level and blast loads considered in the test program.

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