scholarly journals Experimental Assessment on the Flexural Bonding Performance of Concrete Beam with GFRP Reinforcing Bar under Repeated Loading

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Minkwan Ju ◽  
Hongseob Oh
Keyword(s):  
Bond Length ◽  
Repeated Loading ◽  
Variable Loading ◽  
Loading Test ◽  
Variable Amplitude Loading ◽  
Static Test ◽  
Variable Amplitude ◽  
Reinforcing Bar ◽  
Bond Performance ◽  
Bonding Performance

This study intends to investigate the flexural bond performance of glass fiber-reinforced polymer (GFRP) reinforcing bar under repeated loading. The flexural bond tests reinforced with GFRP reinforcing bars were carried out according to the BS EN 12269-1 (2000) specification. The bond test consisted of three loading schemes: static, monotonic, and variable-amplitude loading to simulate ambient loading conditions. The empirical bond length based on the static test was 225 mm, whereas it was 317 mm according to ACI 440 1R-03. Each bond stress on the rib is released and bonding force is enhanced as the bond length is increased. Appropriate level of bond length may be recommended with this energy-based analysis. For the monotonic loading test, the bond strengths at pullout failure after 2,000,000 cycles were 10.4 MPa and 6.5 MPa, respectively: 63–70% of the values from the static loading test. The variable loading test indicated that the linear cumulative damage theory on GFRP bonding may not be appropriate for estimating the fatigue limit when subjected to variable-amplitude loading.

Fatigue crack growth prediction model under variable amplitude loading conditions

2021 ◽  
pp. 105678952199873
Author(s):  
Menghan Li ◽  
Xin Liu ◽  
Zhenguo Li ◽  
Yingbo Zhang
Keyword(s):  
Crack Growth ◽  
Life Prediction ◽  
Stress Ratio ◽  
Crack Size ◽  
Model Parameters ◽  
Remaining Life ◽  
Variable Loading ◽  
Variable Amplitude Loading ◽  
Variable Amplitude ◽  
Crack Growth Model

Crack size prediction under variable amplitude loading is a very complex process, which is also important for life prediction in engineering. A crack growth model considering different stress ratio for fatigue remaining life prediction is proposed in this paper. The model utilizes stress ratio to describe the variable loading sequences, which makes the calculation greatly simplified. The rain-flow method is utilized to characterize the load sequence effects under variable amplitude loading. In addition, particle filter is utilized to estimate the model parameters describing the crack growth. Finally, case study indicates that the proposed approach is efficient in predicting crack growth and fatigue remaining life.

scholarly journals Experimental study on bond performance between GFRP bars and concrete

2020 ◽  
Vol 165 ◽  
pp. 04041
Author(s):  
Fu Decheng ◽  
Wang Bo
Keyword(s):  
Experimental Study ◽  
Bond Strength ◽  
Bond Length ◽  
Concrete Strength ◽  
Bond Failure ◽  
Bond Performance ◽  
Gfrp Bars ◽  
Bonding Performance ◽  
Pull Out ◽  
Gfrp Reinforcement

Based on 27 bonding test of pull-out specimens, the bonding performance between GFRP and concrete was studied systematically. The bond failure between concrete and GFRP includes four stages: microslip stage, linear slip stage, nonlinear slip stage and bond failure stage. The experiment shows that there is no significant correlation between concrete strength and bond strength, bond strength increases with the bond length and decreases with the increase of GFRP reinforcement diameter.

scholarly journals Performance of chosen multiaxial cycle counting method under non-proportional multiaxial variable loading.

2018 ◽  
Vol 165 ◽  
pp. 16008
Author(s):  
Matus Margetin ◽  
Dominik Biro
Keyword(s):  
Fatigue Life ◽  
Testing Machine ◽  
Time Estimation ◽  
Life Time ◽  
Variable Loading ◽  
Data Set ◽  
Variable Amplitude Loading ◽  
Variable Amplitude ◽  
Counting Methods ◽  
Brown's Method

One of the most crucial tasks in fatigue life-time estimation of components loaded with multiaxial variable amplitude loading is to correctly identify loading cycles that can be used with multiaxial damage criterions. During past years, several cycle counting methods have been proposed for multiaxial loading conditions. The aim of this text is the comparison of selected multiaxial cycle counting methods, namely Wang-Brown’s method, Modified Wang-Brown’s method, Bannantine-Socie’s method and then a critical analysis of the obtained results. For the comparison of chosen methods, a new data set, consisting of experimentally obtained results from multiaxial non-proportional variable amplitude loading tests carried on by authors, has been used. The tested specimens were made from S355J0 structural steel and the testing procedure has been carried out on the MTS Axial/Torsion servo hydraulic testing machine. Findley and McDiarmid multiaxial criterion with Palgren-Miner summation rule have been used for fatigue life-time estimation of the tested specimens.

scholarly journals Influence of Roughness on Shear Bonding Performance of CFRP-Concrete Interface

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1875 ◽  
Author(s):  
Yushi Yin ◽  
Yingfang Fan
Keyword(s):  
Surface Roughness ◽  
Bond Length ◽  
Interfacial Bonding ◽  
Interface Roughness ◽  
Fiber Reinforced ◽  
Bond Slip ◽  
Practical Applications ◽  
Bond Performance ◽  
Bonding Performance ◽  
Concrete Interface

The potential of Fiber Reinforced Polymer (FRP) in the reinforcement of concrete structures has been shown in many studies and practical applications. However, few works have focused systematically on the development of quantitative criteria to measure surface roughness and relate this parameter to the bonding mechanical property. Moreover, some researchers have declared that, if the concrete interface is rougher, the bond performance between FRP and concrete will be increase, However, there is no answer to how rough the surface is. There are limited application standards for engineers to conduct in FRP reinforcement projects. This work evaluated several concrete specimens with three different strengths and six types of interface roughness. A single shear test was conducted to study the influence of surface roughness on the interfacial bonding performance of a carbon fiber-reinforced composite (CFRP)-concrete beam. The results show that, among the six interfaces, a concrete interface with the roughness of 0.44 has the best interfacial bonding performance. An interfacial appearance with the cement mortar almost cleaned away, and almost one fifth of the single coarse aggregate bared will get the best bond performance. Roughness parameters significantly influenced the effective bond length. The effective bond length of the six interfaces experienced an overall decreasing trend as the roughness increased. The bond–slip curves of concrete interfaces with roughness of 0.25–0.44 did not significantly change the rigidity within the brittle region. The rougher the interface was, the shorter the brittle region was. After entering a plasticity stage, the bond–slip curves for the six types of interfaces all declined with different slopes, and the max slip values were 0.04–0.35 mm when debonding failure occurred.

Application of the Strip Yield Model to Crack Growth Predictions for Structural Steel

2010 ◽  
Vol 57 (1) ◽  
pp. 1-20
Author(s):  
Małgorzata Skorupa ◽  
Tomasz Machniewicz
Keyword(s):  
Structural Steel ◽  
Crack Growth ◽  
Model Calibration ◽  
Load History ◽  
Yield Model ◽  
Variable Amplitude Loading ◽  
Variable Amplitude ◽  
Constraint Factors ◽  
Strip Yield Model ◽  
Closure Mechanism

Application of the Strip Yield Model to Crack Growth Predictions for Structural SteelA strip yield model implementation by the present authors is applied to predict fatigue crack growth observed in structural steel specimens under various constant and variable amplitude loading conditions. Attention is paid to the model calibration using the constraint factors in view of the dependence of both the crack closure mechanism and the material stress-strain response on the load history. Prediction capabilities of the model are considered in the context of the incompatibility between the crack growth resistance for constant and variable amplitude loading.

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