Fire Resistance of Structural Concrete Retrofitted with Carbon Fiber–Reinforced Polymer Composites

2015 ◽  
Vol 2522 (1) ◽  
pp. 151-160 ◽  
Author(s):  
D. V. Reddy ◽  
Khaled Sobhan ◽  
Jody D. Young
Keyword(s):  
Carbon Fiber ◽  
Fire Resistance ◽  
Fire Protection ◽  
Fiber Reinforced Polymers ◽  
Experimental Investigations ◽  
Small Scale ◽  
Fire Exposure ◽  
Fiber Reinforced ◽  
Rc Structures ◽  
Carbon Fiber Reinforced

This paper presents an experimental investigation for evaluating the effects of fire exposure on properties of structural elements retrofitted by carbon fiber–reinforced polymers (CFRPs). Mechanical properties of CFRP-strengthened reinforced concrete (RC) members, protected with secondary insulation, were investigated, before and after (residual) direct fire exposure. Direct fire contact resulted in a reduction in capacity of 9% to 20% for CFRP-strengthened RC beams and 15% to 34% for CFRP-strengthened RC columns. Furthermore, a similitude analysis was developed for a heat transfer relationship between full-scale and small-scale specimens, allowing a one-fourth exposure time reduction for the latter. Results from the experimental investigations demonstrated the benefits of employing secondary fire protection to CFRP-strengthened structures, despite the glass transition temperature being exceeded in the early stages of the elevated-temperature exposure. Therefore, it is suggested that fire protection is necessary for a CFRP-strengthened structure to retain integrity throughout the duration of the fire exposure and on return to ambient temperature. The conclusions of this investigation will lead to recommendations and guidelines to designers and practicing engineers for using CFRP materials in retrofitting RC structures with adequate fire resistance by contributing to the missing information for fire protection requirements not available in codes of practice.

Non-Traditional Shape Variations on Bistable Carbon Fiber Reinforced Polymer Laminates

2020 ◽  
Author(s):  
Christopher M. Nelon ◽  
Jonathan Figueroa ◽  
Oliver J. Myers ◽  
Aaron Shepard
Keyword(s):  
Finite Element ◽  
Carbon Fiber ◽  
Large Scale ◽  
Fiber Reinforced Polymers ◽  
Small Scale ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Carbon Fiber Reinforced ◽  
Polymer Laminates

Abstract The ability of a material to display two equilibrium states, called bistability, has been previously observed in carbon fiber reinforced polymers (CFRPs). For bistability to occur, the laminate must consist of an unsymmetric layup about its midplane which generates internal residual stress from thermal contraction. Prior studies have observed bistability in CFRPs with small-scale rectangular geometries where all sides were less than 250 mm. The aim of this paper is to demonstrate the existence of bistability in large-scale CFRPs with rectangular and non-rectangular geometries. Experiments and finite element analyses were conducted to determine the viability of bistability in large-scale CFRPs where at least one length aspect of the specimen was greater than or equal to 304.8 mm. Specimens whose shapes included rectangles, deltoids, triangles, and circles, were fabricated and tested to determine the presence of bistability and the associated curvature for each cured equilibrium state. Rectangular specimens had a side length of 914.4 mm and widths that varied from 177.8 to 457.2 mm. For the deltoids, triangles, and circles, one length aspect (i.e. the height, hypotenuse, and diameter, respectively) equaled 304.8 mm. Finite element models were created to compare the equilibrium shapes’ curvatures and displacements with the experimental laminates; the existence of bistability was also examined using a nondimensionalized bifurcation plot. Experimentally, bistability was found to occur for the fabricated laminates up to six plies. As the studied laminates could be considered thin, they displayed cylindrical cured shapes. The non-traditional shaped CFRPs followed bistability trends found for traditional, small-scale, rectangular laminates. An inverse relationship between the ply count and curvature was exhibited for the large-scale, rectangular laminates; curvature decreased as the number of plies in the laminate increased.

Accuracy and surface quality of abrasive waterjet machined CFRP composites

2020 ◽  
pp. 002199832097442
Author(s):  
HA Youssef ◽  
HA El-Hofy ◽  
AM Abdelaziz ◽  
MH El-Hofy
Keyword(s):  
Surface Roughness ◽  
Carbon Fiber ◽  
Removal Rate ◽  
Kerf Width ◽  
Fiber Reinforced Polymers ◽  
Abrasive Waterjet ◽  
Experimental Investigations ◽  
Fiber Reinforced ◽  
Cfrp Laminates ◽  
Carbon Fiber Reinforced

The use of carbon fiber-reinforced composites is increasing today since they have an excellent weight-to-mechanical properties ratio. Traditional machining of this material is difficult. Abrasive water jet machining (AWJM) is an advanced non-traditional material removal process that can machine hard-to-cut materials. The process is widely used in aerospace, marine, and automotive industries. However, it encounters several challenges when cutting carbon fiber reinforced polymers (CFRP). The present work aims to study the characteristics of AWJM of CFRP laminates. Detailed experimental investigations are conducted to explore the effect of traverse feed and standoff distance (SOD) on top kerf width, bottom kerf width, kerf angle, profile area, volumetric removal rate, and the average surface roughness, and jet deviation factor. Repeatability tests are also used to assess the kerf dimensional accuracy and surface roughness tolerance achieved by AWJM of CFRP laminates. Results showed that the surface roughness increases along with the cut thickness, especially at large traverse feed and SOD. Both the kerf taper angle and the volumetric removal rate increase with traverse feed and SOD.

scholarly journals Performance of Reinforced Concrete Beams Strengthened with Carbon Fiber Reinforced Polymer Strips

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5866
Author(s):  
Muhammad Haroon ◽  
Jae-Sang Moon ◽  
Changhyuk Kim
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Load Level ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced Polymers ◽  
Fiber Reinforced ◽  
Shear Strengthening ◽  
Rc Structures ◽  
Strength Capacity ◽  
Carbon Fiber Reinforced

Carbon fiber reinforced polymers (CFRP) have shown considerable potential in the repair and rehabilitation of deficient reinforced concrete (RC) structures. To date, several CFRP strengthening schemes have been studied and employed practically. In particular, strengthening of shear damaged RC members with CFRP materials has received much attention as an effective repair and strengthening approach. Most existing studies on strengthening shear-deficient RC members have used unidirectional CFRP strips. Recent studies on strengthened T-beams demonstrated that a bidirectional CFRP layout was more effective than a unidirectional layout. As such studies are limited, in this study, the feasibility of bidirectional CFRP layouts for the shear strengthening of rectangular RC beams was experimentally evaluated. Bidirectional layout details with CFRP anchors as well as rehabilitation timing were considered and investigated. The test results showed that the members with a bidirectional CFRP layout carried less shear strength capacity than those with unidirectional layouts for the same quantity of CFRP material. Nevertheless, the bidirectional CFRP layout allowed for a uniformly distributed stirrup strain compared to the unidirectional CFRP layout at the same load level, which increased the efficiency of the transverse reinforcement. Additionally, the shear contribution of CFRP material according to the CFRP strengthening timing was verified.

scholarly journals Ultrasonic Imaging of Thick Carbon Fiber Reinforced Polymers through Pulse-Compression-Based Phased Array

2021 ◽  
Vol 11 (4) ◽  
pp. 1508
Author(s):  
Muhammad Khalid Rizwan ◽  
Stefano Laureti ◽  
Hubert Mooshofer ◽  
Matthias Goldammer ◽  
Marco Ricci
Keyword(s):  
Carbon Fiber ◽  
Pulse Compression ◽  
Phased Array ◽  
Signal To Noise Ratio ◽  
Near Field ◽  
Ultrasonic Imaging ◽  
Fiber Reinforced Polymers ◽  
Fiber Reinforced ◽  
Custom Made ◽  
Carbon Fiber Reinforced

The use of pulse-compression in ultrasonic non-destructive testing has assured, in various applications, a significant improvement in the signal-to-noise ratio. In this work, the technique is combined with linear phased array to improve the sensitivity and resolution in the ultrasonic imaging of highly attenuating and scattering materials. A series of tests were conducted on a 60 mm thick carbon fiber reinforced polymer benchmark sample with known defects using a custom-made pulse-compression-based phased array system. Sector scan and total focusing method images of the sample were obtained with the developed system and were compared with those reconstructed by using a commercial pulse-echo phased array system. While an almost identical sensitivity was found in the near field, the pulse-compression-based system surpassed the standard one in the far-field producing a more accurate imaging of the deepest defects and of the backwall of the sample.

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