Fatigue-Cumulative Damage Model of RC Crane Girders Strengthened with FRP Strips

The cumulative damage of the reinforced concrete (RC) crane girders occurred by overload, fatigue and other reasons in service may deteriorate the safety of RC crane girders seriously, so it is necessary to analyze the damage mechanism and rationally reinforce them in good time. In this paper, RC crane girder strengthened with CFRP strips is taken as a target, and the mechanical performance degradation under fatigue load is studied. According to the basic theory of continuum damage mechanics, a damage variable is defined by flexural rigidity, and fatigue- cumulative damage model, which describes the process of damage and fracture, is established. The variation law of cumulative damage of RC crane girders strengthened with FRP strips under crane load is discussed, and the failure patterns such as concrete cracking, debonding between CFRP strips and concrete, yield of steel bars etc., are studied. The criterion which can be used to estimate the cumulative damage degree of strengthened RC crane girders is proposed. Finally, the evolution of the fatigue damage in the RC crane girders strengthened with CFRP strips is numerically simulated, and the results show that the proposed model can correctly describe the damage and failure process of strengthened RC crane girders. The research will provide a reference for the damage analysis and reinforcement of RC crane girders strengthened with CFRP strips.

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Modelling of Thermal Cracking Behaviours of Fiber-Reinforced Composites

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.334-335.237 ◽

2007 ◽

Vol 334-335 ◽

pp. 237-240

Author(s):

Tao Xu ◽

Shan Yong Wang ◽

Chun An Tang ◽

Li Song ◽

Shi Bin Tang

Keyword(s):

Process Analysis ◽

Failure Process ◽

Damage Model ◽

Mechanical Damage ◽

Thermal Cracking ◽

Model Material ◽

Thermal Mismatch ◽

Failure Patterns ◽

Damage And Fracture ◽

The Matrix

In this paper, a coupled thermal-mechanical-damage model, Material Failure Process Analysis for Thermo code (abbreviated as MFPA-thermo), was applied to investigate the formation, extension and coalescence of cracks in FRCs, caused by the thermal mismatch of the matrix and the particles under uniform temperature variations. The effects of the thermal mismatch between the matrix and fibers on the stress distribution and crack development were also numerically studied. The influences of the material heterogeneity, the failure patterns of FRCs at varied temperatures are simulated and compared with the experimental results in the present paper. The results show that the mechanisms of thermal damage and fracture of the composite remarkedably depend on the difference between the coefficients of thermal expansion of the fibers and the matrix on a meso-scale. Meanwhile, the simulations indicate that the thermal cracking of the FRCs at uniform varied temperatures is an evolution process from diffused damage, nucleation, and finally linkage of cracks.

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Nonlinear cumulative damage model and application to bridge fatigue life evaluation

Advances in Structural Engineering ◽

10.1177/1369433217746344 ◽

2017 ◽

Vol 21 (9) ◽

pp. 1402-1408

Author(s):

Huili Wang ◽

Sifeng Qin ◽

Yunjie Wang

Keyword(s):

Fatigue Life ◽

Damage Mechanics ◽

Damage Model ◽

Cumulative Damage ◽

Life Evaluation ◽

Cumulative Rate ◽

Miner’S Rule ◽

Fatigue Life Evaluation ◽

Cumulative Damage Model ◽

Miner's Rule

Fatigue is a damage accumulation process in which material property deteriorates continuously. Fatigue life prediction issues are important for safety. This article aims to develop a nonlinear cumulative damage model. A fatigue damage model based on the continuum damage mechanics is addressed and applied to bridge fatigue life evaluation. First, the bridge nonlinear cumulative damage model based on damage mechanics is propounded and equivalent effective stress range is given. Then, the effects of the main parameter in the model are analyzed. Finally, Xinghai Bay Bridge is taken as a case study. The results indicate that the damage is increased with the material parameter [Formula: see text] reduced. [Formula: see text] is a material parameter depending on stress amplitude and without physical meaning. If [Formula: see text], the effect of [Formula: see text] is negligible. If [Formula: see text], nonlinear cumulative damage model degrades into Miner’s rule and effect of [Formula: see text] to structural damage is maximum. The cumulative damage curve calculated by the nonlinear cumulative damage model is nonlinear, with a low cumulative rate initially but a very high cumulative rate at the end of the design life, whereas the Miner’s rule is linear. The nonlinear cumulative damage model can reflect actual damage process, while Miner’s rule is pessimistic.

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Damage Analysis and Numerical Simulation for Failure Process of Extra-Long Pre-Stressed Concrete Beams

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.368-373.1318 ◽

2011 ◽

Vol 368-373 ◽

pp. 1318-1322

Author(s):

Jian Yuan ◽

Wen Gang Zhu ◽

Min Chen

Keyword(s):

Damage Mechanics ◽

Concrete Beams ◽

Failure Process ◽

Damage Model ◽

Mechanics Model ◽

Damage And Fracture ◽

Tension And Compression ◽

Damage Constitutive Model ◽

Damage Theory ◽

Elastic Damage

The failure process for an extra-long pre-stressed concrete beam under static loads was simulated based on the elastic damage theory with the commercial software ABAQUS. By taking account of the different damage behaviors of concrete under tension and compression conditions, a damage mechanics model with three independent parameters was derived from the elastic damage theory. By combining the proposed damage model with the ABAQUS, the damage model was added to UMAT user subroutine. This method was developed to analyze the failure process of the extra-long pre-stressed concrete beams. The theoretical results show that the proposed damage constitutive model can be applied to describe the damage and fracture behaviors of the extra-long pre-stressed concrete beams.

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Continuum Damage Mechanics Approach for Modeling Cumulative-Damage Model

Mathematical Problems in Engineering ◽

10.1155/2021/7136846 ◽

2021 ◽

Vol 2021 ◽

pp. 1-12

Author(s):

Haoran Li ◽

Jiadong Wang ◽

Juncheng Wang ◽

Ming Hu ◽

Yan Peng

Keyword(s):

Fatigue Life ◽

Damage Mechanics ◽

Stress Amplitude ◽

Damage Model ◽

Continuum Damage Mechanics ◽

Cumulative Damage ◽

Continuum Damage ◽

Variable Loading ◽

Cumulative Damage Model ◽

Additional Hardening

In this study, we propose a novel cumulative-damage model based on continuum damage mechanics under situations where the mechanical components are subjected to variable loading. The equivalent completely reversed stress amplitude accounting for the effect of mean stress, stress gradients, loading history, and additional hardening behavior related to nonproportional loading paths on high-cycle fatigue under variable loading is elaborated. The effect of mean stress, stress gradients, loading history, and additional hardening behavior related to nonproportional loading paths is considered by averaging the superior limit of the intrinsic damage dissipation work in the critical domain. We developed a novel cumulative-damage model by introducing the equivalent completely reversed stress amplitude into the damage-evolution model. For better comparison, existing cumulative-damage models, including the Palmgren–Miner law, corrected Palmgren–Miner law, Morrow’s plastic work interaction rule, and Wang’s rule, were employed to predict the fatigue life under variable loading. The proposed model performed better, considering the error scatter band obtained by plotting the predicted and experimental fatigue life on the same coordinate system. The model precisely predicts fatigue life under variable loading and easily identifies its material constants.

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