New mechanics-based confinement model and stress–strain relationship for analysis and design of concrete columns wrapped with FRP composites

Structures ◽  
2021 ◽  
Vol 33 ◽  
pp. 2659-2674
Author(s):  
Koosha Khorramian ◽  
Pedram Sadeghian
Keyword(s):  
Concrete Columns ◽  
Stress Strain ◽  
Analysis And Design ◽  
Frp Composites ◽  
Strain Relationship ◽  
Confinement Model

Behavior and modeling of post-heated circular concrete specimens repaired with fiber-reinforced polymer composites

2021 ◽  
pp. 136943322110585
Author(s):  
Seyed Mehrdad Elhamnike ◽  
Rasoul Abbaszadeh ◽  
Vahid Razavinasab ◽  
Hadi Ziaadiny
Keyword(s):  
Strain Curve ◽  
Concrete Columns ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Concrete Members ◽  
Frp Composites ◽  
Reinforced Polymer ◽  
Fiber Reinforced Polymer Composites

Exposure of buildings to fire is one of the unexpected events during the life of the structure. The heat from the fire can reduce the strength of structural members, and these damaged members need to be strengthened. Repair and strengthening of concrete members by fiber-reinforced polymer (FRP) composites has been one of the most popular methods in recent years and can be used in fire-damaged concrete members. In this paper, in order to provide further data and information about the behavior of post-heated circular concrete columns confined with FRP composites, 30 cylindrical concrete specimens were prepared and subjected under four exposure temperatures of 300, 500, 700, and 900. Then, specimens were repaired by carbon fiber reinforced polymer composites and tested under axial compression. Results indicate that heating causes the color change, cracks, and weight loss of concrete. Also, with the increase of heating temperature, the shape of stress–strain curve of FRP-retrofitted specimens will change. Therefore, the main parts of the stress–strain curve such as ultimate stress and strain and the elastic modulus will change. Thus, a new stress–strain model is proposed for post-heated circular concrete columns confined by FRP composites. Results indicate that the proposed model is in a good agreement with the experimental data.

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).

Flexural-Shear Behavior of High-Strength Concrete Short Columns

2001 ◽  
Vol 17 (4) ◽  
pp. 679-695 ◽  
Author(s):  
Armen Martirossyan ◽  
Yan Xiao
Keyword(s):  
High Strength Concrete ◽  
Axial Load ◽  
High Strength ◽  
Concrete Columns ◽  
Experimental Program ◽  
Stress Strain ◽  
Strength Concrete ◽  
Short Columns ◽  
Strain Relationship ◽  
High Strength Concrete Columns

This paper discusses the seismic performance of high-strength concrete columns. The research is a part of an ongoing comprehensive experimental program to investigate seismic design methods of high-strength concrete structures. The first stage of the program involved testing of fifteen high-strength concrete stub columns under concentric axial compression. The concrete compressive strength was about 69 MPa (10,000 psi). In addition, a large database including eighty-six similar tests conducted by other researchers was constructed, and stress-strain behavior of high-strength concrete was investigated. Based on the analysis, a stress-strain relationship for high-strength concrete columns was proposed. Secondly, six 1/3-1/2 scale high-strength concrete short columns were tested under combined axial load and cyclic shear, with double curvature condition. The primary experimental parameters included axial load ratio, longitudinal reinforcement ratio, and volumetric ratio of transverse reinforcement. The proposed stress-strain relationship was used in the analysis of the lateral force–displacement relationship for high-strength concrete columns. Moment-curvature analysis, based on proposed equivalent stress block approach, as well as plastic hinge mechanism, has been incorporated in this analytical tool. The analytical results agreed well with the primary load-deflection envelopes obtained from the tests.

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