Experimental Study on CFRP-Bonded Steel Plates with Thickness Reduction Using Underwater Epoxy

2011 ◽  
Vol 117-119 ◽  
pp. 373-379
Author(s):  
Xiao Chen ◽  
Yasuo Kitane ◽  
Yoshito Itoh
Keyword(s):  
Epoxy Adhesive ◽  
Steel Plates ◽  
Fiber Reinforced Polymer ◽  
Structural Performance ◽  
Carbon Fiber Reinforced Polymer ◽  
Curing Process ◽  
Test Results ◽  
Initial Stiffness ◽  
Reinforced Polymer ◽  
Loading Tests

This paper presents a series of uniaxial loading tests on the thickness-reduced steel plates bonded with carbon fiber reinforced polymer (CFRP) strand sheets using underwater epoxy as adhesive. Four sets of material test are carried out on epoxy coupons at different curing times. Repaired performance of CFRP-bonded steel plates is investigated in terms of initial stiffness, yield strength, and failure mode of the specimens. Test results showed that the structural performance of CFRP-bonded steel plates does not reach the expected design level due to a slow curing process of epoxy adhesive in this study. The curing effects of epoxy adhesive on the repaired performance are discussed.

scholarly journals Analytical and Experimental Study of Residual Stresses in CFRP

2013 ◽  
Vol 2013 ◽  
pp. 1-4
Author(s):  
Chia-Chin Chiang ◽  
Vu Van Thuyet ◽  
Shih-Han Wang ◽  
Liren Tsai
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Curing Process ◽  
Cooling Process ◽  
Element Analysis ◽  
Reinforced Polymer ◽  
Fiber Reinforced Polymer Composites ◽  
Good Environment

Fiber Bragg Grating sensors (FBGs) have been utilized in various engineering and photoelectric fields because of their good environment tolerance. In this research, residual stresses of carbon fiber reinforced polymer composites (CFRP) were studied using both experimental and analytical approach. The FBGs were embedded inside middle layers of CFRP to study the formation of residual stress during curing process. Finite element analysis was performed using ABAQUS software to simulate the CFRP curing process. Both experimental and simulation results showed that the residual stress appeared during cooling process and the residual stresses could be released when the CFRP was machined to a different shape.

Numerical Investigation on Surface Crack Growth in Steel Plates Repaired With Carbon Fiber-Reinforced Polymer

2019 ◽  
Author(s):  
Zongchen Li ◽  
Xiaoli Jiang ◽  
Hans Hopman
Keyword(s):  
Crack Growth ◽  
Surface Crack ◽  
Steel Structures ◽  
Steel Plates ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Surface Cracks ◽  
Fiber Reinforced ◽  
Reinforced Polymer ◽  
Surface Crack Growth

Abstract Fatigue crack growth is a major challenge to the structural integrity of steel structures. In technical practice, surface cracks are of great importance since cracks in components and structures often exhibit this geometry. Fiber-reinforced polymer (FRP) strengthening technology is a reliable technique to repair cracks in steel structures. Yet the investigation on FRP repairing surface cracks in steel structures is lacking. What’s more, the crack growth might cause crack-induced debonding at the interface of FRP reinforcement, generating negative effects to the reinforcement effectiveness. Unfortunately, there are limited studies in the open literature for this issue. In this paper, we conduct the investigation on surface crack growth in steel plates reinforced with Carbon Fiber-reinforced polymer (CFRP) under tensile load. Three-dimensional finite element models are built to predict the stress intensity factors of the surface cracks. The crack-induced debonding is considered in the finite element analysis by introducing the cohesive zone model and a bond failure criterion. In accordance with Paris law, surface crack growth rate of different models are predicted. The influential parameters of crack-induced debonding are analyzed by means of parametric studies. The results indicate that CFRP reinforcement could significantly decrease the surface crack growth rate, while the crack-induced debonding might generate negative effect on CFRP reinforcement. In addition, the crack-induced debonding is affected by not only the interfacial properties, but also the reinforcement scheme, such as thickness of the adhesive layer, CFRP layer number and its elastic modulus, and the depth of surface cracks.

scholarly journals Bond Relationship of Carbon Fiber-Reinforced Polymer (CFRP) Strengthened Steel Plates Exposed to Service Temperature

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3761
Author(s):  
Hui Li Lye ◽  
Bashar S. Mohammed ◽  
Mohamed Mubarak Abdul Wahab ◽  
Mohd Shahir Liew
Keyword(s):  
Carbon Fiber ◽  
Flexural Strength ◽  
Steel Plates ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Service Temperature ◽  
Fiber Reinforced ◽  
Reinforced Polymer ◽  
Adhesion Failure ◽  
Relationship Of

Emerging as a new technology, carbon fiber-reinforced polymer (CFRP) has been introduced to rehabilitate and strengthen steel structures using an adhesive agent. However, the outdoor service temperature is potentially degrading to the mechanical strength of the adhesive, as well as affecting the bonding of the strengthened steel structure. Therefore, this paper aims to investigate the bond relationship of CFRP-strengthened steel plates exposed to service temperatures. Two types of experiments were conducted to determine the tensile and flexural performance of CFRP-strengthened steel plates. The experiments were designed using a Box–Behnken design (BBD) and response surface methodology (RSM) by considering three parameters: service temperature (25 °C, 45 °C and 70 °C), number of CFRP layers (one, three and five layers) and bond length (40, 80 and 120 mm). The findings show the dominant failure mode transformed from adhesion failure between steel and adhesive interfaces to adhesion failure between CFRP and adhesive interfaces as the service temperature increased. The tensile strength improved by 25.62% when the service temperature increased. Field emission scanning electron microscope (FESEM) analysis proved that the strength enhancement is due to the densification and reduction of the adhesive particle microstructure gaps through the softening effect at service temperature. However, service temperature is found to have less impact on flexural strength. Incorporating the experimental results in RSM, two quadratic equations were developed to estimate the tensile and flexural strength of CFRP-strengthened steel plates. The high coefficient of determination, R2, yields at 0.9936 and 0.9846 indicate the high reliability of the models. Hence, it can be used as an estimation tool in the design stage.

scholarly journals Experimental Study on Structural Degradation of CFRP Strengthened RC Beams Subjected to Weak Interfaces

2016 ◽  
Vol 10 (1) ◽  
pp. 384-401
Author(s):  
Xiaogang Wang ◽  
Wenwu Fan ◽  
Xiangbo Du ◽  
Zhaoxin Fang
Keyword(s):  
Early Stage ◽  
Fiber Reinforced Polymer ◽  
Structural Performance ◽  
Carbon Fiber Reinforced Polymer ◽  
Rc Beams ◽  
Shear Transfer ◽  
Reinforced Polymer ◽  
Externally Bonded ◽  
Strengthened Beam ◽  
Cover Thickness

The performance of corroded reinforced concrete (RC) beams strengthened with externally bonded carbon fiber reinforced polymer (CFRP) materials may be affected by a weak interface caused either by defective bonding between the new and old concrete in the case of cover replacement or by expansive cracks in the case of direct application. To investigate this effect, thirteen strengthened beam specimens with preinstalled horizontal weak interfaces were designed and tested in monotonic bending. Through analysis of the experimental results, in terms of load deflection curves and the derived bond stress distribution, it was found that intermediate delamination was induced by the weak interfaces, which greatly impaired the integrity of the strengthening system and eventually led to CFRP integral debonding without lateral confinement. Degradation of the shear transfer ability through the interface can be expected due to interfacial weakening, increasing of the CFRP reinforcement ratio and reduction of cover thickness. Crack-induced weak interfaces caused less serious damage at the early stage but induced more dramatic degradation as cracks expanded. U-strip confinement was found to be effective in improving the structural performance of the strengthened beam and preventing CFRP integral debonding. Nevertheless, intermediate delamination cannot be prevented, increasing the risk of CFRP premature rupture and end anchorage failure.

scholarly journals Experimental Study on Slender CFRP-Confined Circular RC Columns under Axial Compression

2021 ◽  
Vol 11 (9) ◽  
pp. 3968
Author(s):  
Zhongjun Hu ◽  
Quanheng Li ◽  
Hongfeng Yan ◽  
Yuchuan Wen
Keyword(s):  
Axial Compression ◽  
Slenderness Ratio ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Test Results ◽  
Rc Columns ◽  
Compression Load ◽  
Reinforced Polymer ◽  
Load Carrying ◽  
Practical Engineering

The test results on the performance of carbon fiber-reinforced polymer (CFRP)-confined reinforced concrete (RC) columns under axial compression load are presented in this study. Twelve slender CFRP-confined circular RC columns with a diameter of 200 mm were divided into two groups. Six specimens with different slenderness ratios of 12, 20, 32, 40, 48, and 56 were contained in each group. The experimental results demonstrated the circumferential CFRP wrap was effective in enhancing the ultimate axial load of slender CFRP-confined circular RC columns compared with unwrapped RC columns. The experimental investigation also showed that the slenderness of the specimens had important influences on the axial compressive behavior, and the axial bearing capacity of slender CFRP-confined circular RC columns decreased as the slenderness ratio increased. In order to predict the load-carrying capacities of slender CFRP-confined circular RC columns, a formula was proposed and the prediction agreed with the experiments. The slenderness of slender CFRP-confined circular RC columns was recommended to be less than 26.5 in practical engineering.

Durability of Broken Concrete Specimens Strengthened with CFRP Sheets

2010 ◽  
Vol 123-125 ◽  
pp. 1119-1122
Author(s):  
Ming Ju Lee ◽  
Ming Gin Lee ◽  
Yi Shuo Huang ◽  
Yang Hsin Liang
Keyword(s):  
Flexural Strength ◽  
Flat Surface ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Load Carrying Capacity ◽  
Test Results ◽  
Cfrp Sheets ◽  
Reinforced Polymer ◽  
Load Carrying ◽  
Externally Bonded

Carbon fiber-reinforced polymer (CFRP) composites are thin laminates that are externally bonded to broken concrete specimens using an epoxy system to increase their load-carrying capacity in this study. This paper reports the test results of broken concrete specimens strengthened with CFRP sheets and subjected to two aggressive environments including ultraviolet (UV) and freeze-thaw cycles. Test results revealed that three different CFRP layers are effective in retrofit on the broken compressive or flexural concrete specimens. The broken concrete specimens repaired with an epoxy and CFRP system could improve their compressive strength, flexural strength or ductility. Both aggressive environment tests didn’t cause obvious degradation to hardness index, compressive or flexural strength. The flexural specimens used half-U coating and anchorage systems were much higher strength than those only wrapped with CFRP sheets on the flat surface.

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