Design-oriented axial stress–strain model for partially fiber-reinforced-polymer-confined normal-strength concrete

2020 ◽  
Vol 23 (16) ◽  
pp. 3481-3495
Author(s):  
Junlong Yang ◽  
Jizhong Wang ◽  
Ziru Wang
Keyword(s):  
Axial Stress ◽  
Concrete Columns ◽  
Fiber Reinforced Polymer ◽  
Confined Concrete ◽  
Normal Strength Concrete ◽  
Stress Strain ◽  
New Model ◽  
Strength Concrete ◽  
Reinforced Polymer ◽  
Normal Strength

Due to the influence of “arching action” in fiber-reinforced polymer (FRP) partially confined concrete columns as a result of the unconfined regions, the confinement of the concrete columns wrapped with discrete FRP strips is less efficient when compared with full wrapping schemes. This study comprehensively investigates the difference of the the confinement mechanism between fully and partially FRP confined circular normal-strength concrete and thus presents a new design-oriented model to predict the stress–strain relationships of partially FRP confined normal-strength concrete. The formulas used to determine the strength and corresponding strain of several key points on the stress–strain curves are also proposed by the regression analysis according to a reliable test database from the relevant literature. Besides, another selected database including 100 FRP partially wrapped circular concrete columns is also collected for model verification. The results show that better performance can be achieved by the new model compared with the selected models in predicting the ultimate conditions of partially FRP confined concrete. Finally, some specimens are chosen to assess the performance of the new model in predicting the complete axial stress–strain curves. The comparisons reveal that satisfactory accuracy and good agreement can be achieved between the theoretical predictions and experimental observations.

scholarly journals Low-Cost Fiber Rope Reinforced Polymer (FRRP) Confinement of Square Columns with Different Corner Radii

Buildings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 355
Author(s):  
Qudeer Hussain ◽  
Anat Ruangrassamee ◽  
Somnuk Tangtermsirikul ◽  
Panuwat Joyklad ◽  
Anil C. Wijeyewickrema
Keyword(s):  
Ultimate Strength ◽  
Predictive Models ◽  
Axial Stress ◽  
Low Cost ◽  
Concrete Columns ◽  
Confined Concrete ◽  
Test Results ◽  
Stress Strain ◽  
Reinforced Polymer

This research investigates the behavior of square concrete columns externally wrapped by low-cost and easily available fiber rope reinforced polymer (FRRP) composites. This study mainly aims to explore the axial stress-strain relationships of FRRP-confined square columns. Another objective is to assess suitable predictive models for the ultimate strength and strain of FRRP-confined square columns. A total of 60 square concrete columns were cast, strengthened, and tested under compression. The parameters were the corner radii of square columns (0, 13, and 26 mm) and different materials of FRRP composites (polyester, hemp, and cotton FRRP composites). The strength and deformability of FRRP-confined specimens were observed to be higher than the unconfined specimens. It was observed that strength gains of FRRP-confined concrete columns and corner radii were directly proportional. The accuracy of ultimate strength and strain models developed for synthetic FRRP-confined square columns was assessed using the test results of this study, showing the need for the development of improved predictive models for FRRP-confined square columns. Newly developed unified models were found to be accurate in predicting the ultimate strength and strain of FRRP-confined columns.

Behavior of Large-Scale Circular and Square RC Columns Confined with Carbon Fiber-Reinforced Polymer under Uniaxial Compression

2010 ◽  
Vol 163-167 ◽  
pp. 3686-3693
Author(s):  
Zhen Yu Wang ◽  
Dai Yu Wang ◽  
Da Gang Lu
Keyword(s):  
Carbon Fiber ◽  
Large Scale ◽  
Axial Stress ◽  
Concrete Columns ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Stress Strain ◽  
Rc Columns ◽  
Reinforced Polymer

Most experimental studies concerning the stress-strain behavior of concrete columns confined with carbon fiber-reinforced polymer (CFRP) focused on plain concrete columns with small section. In this study, 34 concrete columns with large-scale circular and square cross section confined with CFRP were tested under axial compression to investigate the influence of sectional dimensions, internal steel reinforcement and thickness of CFRP jackets on the stress-strain behaviors. Test results indicated that the confinement of CFRP resulted in significant increase in axial stress and strain for circular RC columns, while remarkable enhancement in axial strain but slightly in axial stress for square RC columns. The stress-strain responses of CFRP-confined square RC columns were significantly influenced by sectional dimensions and internal transverse reinforcement. The typical confinement ratio, which is obtained from studies on CFRP-confined unreinforced concrete columns with small cross sections, was not applicable for the case of large-scale square RC columns.

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.

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