Experimental Study on the Axial Compression Behaviors of Short Rectangular Concrete Columns Encased in CFRP Tube

2011 ◽  
Vol 250-253 ◽  
pp. 370-373
Author(s):  
Wen Bin Sun
Keyword(s):  
Axial Compression ◽  
Concrete Columns ◽  
Compression Tests ◽  
Stress Strain ◽  
Concrete Core ◽  
Cfrp Sheets ◽  
Corner Radius ◽  
Cfrp Sheet ◽  
Axial Compressive Strength ◽  
Cfrp Tubes

In this study, 9 short rectangular concrete columns with cross-section 150mm×300mm and height 600mm are prepared, they are 6 confined concrete columns encased in CFRP tubes and three concrete columns as control specimens. The tubes with fibers oriented at hoop direction are manufactured to have 3 or 5 plies of CFRP sheet with 10mm, 20mm, or 40mm rounding corner radius. To ensure proper bond, a 100mm overlap is provided in the direction of fibers. Axial compression tests are conducted to investigate the axial strengths, compression behaviors, stress-strain relationships, and ductility until the CFRP tubes rupture. It is evident that the CFRP tube confinement can improve the behaviors of concrete core, in terms of axial compressive strength or axial deformability. Experimental results also show that the stress-strain behaviors of confined specimens vary with different the layers of CFRP sheets and corner radius at vertical edges.

Experimental Study on the Compressive Behavior of Concrete Encased in CFRP Tubes

2010 ◽  
Vol 168-170 ◽  
pp. 1335-1341
Author(s):  
Wen Bin Sun
Keyword(s):  
Concrete Columns ◽  
Axial Direction ◽  
Compressive Behavior ◽  
Stress Strain ◽  
Strain Behavior ◽  
Corner Radius ◽  
Strain Relationship ◽  
Axial Compressive Strength ◽  
Frp Tube ◽  
Cfrp Tubes

Fiber reinforced polymer (FRP) tube-encased concrete columns represent a formwork-free, steel-free, and corrosion-resistant alternative for a construction of a new infrastructure. In this study, a total of nine square concrete columns with cross-section of 200mm×200mm and height of 600mm including six confined concrete encased in CFRP tubes and three unconfined concrete as control specimens are prepared. The tubes with fibers oriented at 90° from axial direction are manufactured to have 3 or 5 plies of CFRP with 10mm, 20mm, or 40mm rounding corner radius. To ensure proper bond, a 100mm overlap is provided in the direction of fibers. Uniaxial compressive tests are conducted to investigate the axial strength, compressive behavior, stress-strain relationship, and ductility of them throughout the loading history until the CFRP tubes rupture. It is evident that in all cases, the CFRP tube confinement can improve the behavior of unconfined concrete, in terms of axial compressive strength or axial deformability. Test results have shown that the stress-strain behavior of confined specimens vary with different confinement parameters, such as the level of confinement (3-ply and 5-ply), corner radius at vertical edges (10, 20 and 40 mm).

scholarly journals Influence of the Cross–Sectional Shape and Corner Radius on the Compressive Behaviour of Concrete Columns Confined by FRP and Stirrups

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 341
Author(s):  
Yang Wei ◽  
Yang Xu ◽  
Gaofei Wang ◽  
Xunyu Cheng ◽  
Guofen Li
Keyword(s):  
Mechanical Properties ◽  
Axial Compression ◽  
Concrete Columns ◽  
Confined Concrete ◽  
Compression Tests ◽  
Cross Sectional ◽  
Compressive Behaviour ◽  
Corner Radius ◽  
The Cross ◽  
Sectional Shape

Axial compression tests were carried out on 72 FRP (fiber reinforced polymer)–stirrup composite−confined concrete columns. Stirrups ensure the residual bearing capacity and ductility after the FRP fractures. To reduce the effect of stress concentration at the corners of the confined square−section concrete columns and improve the restraint effect, an FRP–stirrup composite−confined concrete structure with rounded corners is proposed. Different corner radii of the stirrup and outer FRP were designed, and the corner radius of the stirrup was adjusted accurately to meet the designed corner radius of the outer FRP. The cross−section of the specimens gradually changed from square to circular as the corner radius increased. The influence of the cross−sectional shape and corner radius on the compressive behaviour of FRP–stirrup composite−confined concrete was analysed. An increase in the corner radius can cause the strain distribution of the FRP to be more uniform and strengthen the restraint effect. The larger the corner radius of the specimen, the better the improvement of mechanical properties. The strength of the circular section specimen was greatly improved. In addition, the test parameters also included the FRP layers, FRP types and stirrup spacing. With the same corner radius, increasing the number of FRP layers or densifying the stirrup spacing effectively improved the mechanical properties of the specimens. Finally, a database of FRP–stirrup composite−confined concrete column test results with different corner radii was established. The general calculation models were proposed, respectively, for the peak points, ultimate points and stress–strain models that are applicable to FRP−, stirrup− and FRP–stirrup−confined concrete columns with different cross−sectional shapes under axial compression.

Experimental Research on Bearing Capacity of Concrete Columns with High Strength Concrete Core under Axial Compression Loading

2012 ◽  
Vol 479-481 ◽  
pp. 2041-2045
Author(s):  
Yue Qi
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Axial Compression ◽  
High Strength Concrete ◽  
High Strength ◽  
Concrete Columns ◽  
Concrete Column ◽  
Reinforced Concrete Column ◽  
Concrete Core ◽  
Strength Concrete

Based on experimental research on plain concrete columns with high strength concrete core, the formula to predict the bearing capacity of concrete columns with high strength concrete core under axial compression loading was brought forward in previous paper, in order to verify the formula whether right, axial compression test including 3 concrete columns with high strength concrete core and 1 ordinary reinforced concrete column were completed, and the failure characteristic was analyzed additionally. According to experimental results, it can be shown that the failure modes of concrete columns with high strength concrete core are similar to that of ordinary reinforced concrete columns, however, the bearing capacity of concrete columns with high strength concrete core is significant higher compared with that of ordinary reinforced concrete column; the results of the bearing capacity obtained by the formula (2) was in good agreement with the experimental results.

Effect of Column Parameters on Axial Compression Behavior of Concrete-Filled FRP Tubes

2005 ◽  
Vol 8 (4) ◽  
pp. 443-449 ◽  
Author(s):  
Zhenyu Zhu ◽  
Iftekhar Ahmad ◽  
Amir Mirmiran
Keyword(s):  
Axial Compression ◽  
Experimental Program ◽  
Test Results ◽  
Compression Tests ◽  
Concrete Core ◽  
Compression Behavior ◽  
Reinforced Polymer ◽  
Dowel Action ◽  
Frp Tubes ◽  
Glass Frp

Axial compression tests have shown fiber reinforced polymer (FRP) tubes to significantly enhance both strength and ductility of concrete columns. However, most experiments and associated models typically do not account for the internal reinforcement, size effect of the column, and the end load-bearing conditions of the tube. An experimental program was undertaken to evaluate the effect of these parameters on the performance of CFFT columns. Glass FRP tubes filled with plain, steel-reinforced, and glass FRP-reinforced concrete were tested with and without end grooves, which would prevent the tube from directly bearing of the axial load. The experiments showed the dowel action of the internal reinforcement to improve the ductility of the columns by restraining the lateral dilation of concrete core. Anempirically derived confinement model, augmented with the stress-strain response of the internal reinforcement, showed close agreement with test results.

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.

Experimental Study on the Bearing Capacity and Ductility of High Strength Concrete Columns Wrapped with CFRP Cloth

2012 ◽  
Vol 166-169 ◽  
pp. 1333-1336
Author(s):  
Zhong Jun Hu ◽  
Yan Xu
Keyword(s):  
Experimental Study ◽  
Bearing Capacity ◽  
High Strength Concrete ◽  
High Strength ◽  
Concrete Columns ◽  
Compression Tests ◽  
Strength Concrete ◽  
Axial Compressive Strength ◽  
High Strength Concrete Columns ◽  
Strength And Ductility

By the axial compression tests on a total of 19 high strength concrete columns wrapped with CFRP cloth, the influence of shape section and different layers on the axial compressive strength and ductility is studied. The experimental results indicated: high strength concrete columns wrapped with CFRP in increasing the bearing capacity and ductility of concrete columns is still valid, its effect on the improvement of ductility is much greater than its capacity.

scholarly journals Effect of Fiber Angles on Hybrid Double-Tube Concrete Columns under Monotonic Axial Compression

2019 ◽  
Vol 2019 ◽  
pp. 1-19 ◽  
Author(s):  
Bing Zhang ◽  
Yu-Jun Qi ◽  
Tao Huang ◽  
Qian-Biao Zhang ◽  
Yu Hu ◽  
...  
Keyword(s):  
Axial Compression ◽  
Axial Strain ◽  
Concrete Columns ◽  
Steel Tube ◽  
Compression Tests ◽  
Research Attention ◽  
Absolute Value ◽  
The Absolute ◽  
Frp Tube ◽  
Hoop Direction

Hybrid double-tube concrete columns (hybrid DTCCs) are a novel form of hybrid columns that combine fiber-reinforced polymer (FRP) composites with two traditional construction materials (i.e., concrete and steel). Hybrid DTCCs consist of an outer FRP tube and an inner steel tube aligned concentrically, with the space between the two tubes and inside of the steel tube filled with concrete. The three materials (i.e., FRP, concrete, and steel) in hybrid DTCCs are combined optimally to deliver excellent performances, such as excellent ductility and remarkable corrosion resistance. Recently, hybrid DTCCs have received increasing research attention on their compressive behavior. Existing studies, however, are focused on hybrid DTCCs with fibers of the FRP tube oriented in the hoop direction or close to the hoop direction. Against this background, this paper presents a series of monotonic axial compression tests on hybrid DTCCs with a particular focus on the effect of fiber angles (i.e., the angle of the fiber orientations to the longitudinal axis of the FRP tube). Three types of fiber angles (i.e., ±45°, ±60°, or ±80°) and two FRP tube thicknesses (i.e., 4 mm and 8 mm) were employed in the present study. Experimental results show that the concrete in hybrid DTCCs is well confined by both the FRP tube and the steel tube, leading to excellent ductility; the confinement effect of the FRP tube increases with the increase of the absolute value of fiber angles, whereas the ultimate axial strain decreases with the increase of the absolute value of fiber angles. An existing analysis-oriented model, which considers the different confining states of the concrete between the two tubes and that inside of the steel tube, is verified using the present test results. The model is capable of providing accurate predictions for hybrid DTCCs with a ±80° FRP tube. For hybrid DTCCs with a ±45° or ±60° FRP tube, the model yields reasonable accurate predictions for the peak axial load but underestimates the ultimate axial strain consistently.

scholarly journals Overall buckling behaviour of laminated CFRP tubes with off-axis ply orientation in axial compression

2019 ◽  
Vol 26 (1) ◽  
pp. 230-239 ◽  
Author(s):  
Ruijie Zhu ◽  
Feng Li ◽  
Dongdong Zhang
Keyword(s):  
Axial Compression ◽  
Test Data ◽  
Slenderness Ratio ◽  
High Stress ◽  
Reduction Factor ◽  
Compression Tests ◽  
Future Design ◽  
High Stress Level ◽  
Cfrp Tubes ◽  
Overall Buckling

AbstractThis paper presents an experimental investigation of overall buckling behaviour of carbon fibre reinforced plastic (CFRP) tubes with different off-axis ply orientations. A series of specimens are designed and prepared with stacking sequences [0∘4/±θ∘], with θ corresponding to either 0, 90, 45 or 60. Axial compression tests with effective end-reinforcement and hinge support are performed to investigate the overall buckling behaviour. With respect to the future design and application of CFRP tubes with this type of stacking sequence, column curves for each stacking sequences and all test data are fitted based on Perry-Robertson formula. With respect to the high stress level in the relatively short CFRP tube that facilitates the development of defects, test data present high levels of discreetness. We propose a strategy for engineering safe design in which a reduction factor is added to the original reduction factor based on statistical analysis when the universal slenderness ratio is less than 2.

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