Fatigue Life Of Concrete Research Articles

Experimental and theoretical evidence for the load sequence effect in the compressive fatigue behavior of concrete

A realistic prediction of the concrete fatigue life exposed to high-cycle loading scenarios with variable amplitudes is of utmost importance for a reliable and economically efficient design of civil engineering infrastructure for transport and energy supply. Current design codes estimate the fatigue life under variable amplitudes using the Palmgren–Miner rule, which assumes a linear scaling between lifetimes measured for uniform cyclic loading scenarios. Several experimental series conducted in the past, however, indicate that this assumption is not valid and that it may lead to unsafe design. In this paper, an experimental and theoretical investigations of the fatigue loading sequence effect in normal- and high-strength concrete behavior are presented, which confirm this observation. In particular, a test campaign with 135 cylinder specimens, including three concrete grades and six different loading scenarios has been conducted. Several response characteristics of the fatigue behavior including Wöhler curves, fatigue creep curves and evolving shapes of hysteretic loops have been evaluated. To substantiate the experimental results, a theoretical explanation of the observed sequence effect is formulated based on the assumption, that energy is dissipated uniformly within the volume of a test specimen during subcritical, compressive cyclic loading. Then, superposition of energy dissipation profiles along the lifetime measured for constant amplitudes becomes possible and a theoretical justification of the experimentally observed sequence effect can be provided. Moreover, a reverse sequence effect reported in the literature for bending fatigue of concrete can then be explained by an unevenly distributed energy dissipation over a cracked specimen. Supported by the theoretical consideration, the processed experimental data is used to validate existing fatigue life assessment rules by testing their ability to reflect the load sequence effect.

Flexural Behavior of Polypropylene Fiber Reinforced Concrete Beams with Super elastic Wire Under Repeated Loading

This paper investigates the effect of polypropylene fiber (PPM-12) and nitinol (NiTi) superelastic Shape Memory Alloy (SMA) wires in concrete beams under flexural repeated loading. For this purpose, nine of simply supported beams with dimensions of (1000 mm length, 80 mm width and 125 mm depth) were considered. Test specimens were divided into three groups (G1, G2 and G3). Specimens in group G2 and G3 were reinforced with different ratios of PPM-12 fiber (0.5%and 0.75%) by volume of concrete and threaded (NiTi) superelastic SMA wires. Group G1 was reinforced with traditional steel rebar and SMA wires without PPM-12 fiber. The results revealed that the addition of PPM-12 fiber to concrete have a negative effect on the mechanical properties of concrete with respect to load carrying capacity in the other side the addition of fiber led to a controlled crack propagation in concrete and increased the fatigue life of concrete. The (NiTi) superelastic threaded wires were active in some specimens in which some displacement recovery was noticed. The importance of study is how to enhance concrete life and reducing crack propagation in concrete by using polypropylene fiber and NiTi wire as reinforcement in concrete.

A Review on Fatigue Life Prediction of Plain Concrete

Fatigue analysis of concrete structures is important since it is the limiting factor to service life of many infrastructures. The heterogeneity in concrete and its complex behaviour upon repetitive loading makes the fatigue life prediction of concrete erratic. This paper presents a review on the fatigue life prediction models of plain concrete. Review includes the deterministic and probabilistic approach for the prediction of fatigue life of concrete. It has been observed that deterministic approach depends on certain parameters and initial conditions and is not reliable for the prediction of fatigue life of concrete. So there is a demand for a more generalised model based on probabilistic approach which includes randomness in the fatigue failure of concrete. Recent studies show utilisation of artificial neural network, a computational tool based on this approach can be utilised to predict the fatigue behaviour of concrete.

Material and Size Effect on Fatigue Damage of Concrete for Pavement Application

Highway pavements need to withstand repeated and varying traffic loads due to which they may fail at a stress level lower than their strength called fatigue. Fatigue is the progressive damage due to propagation of cracks and is considered to be the primary cause of structural failure in concrete pavement. The propagation of cracks in concrete is resisted by the fracture toughness, which is a material property. Stress intensity factor is used to express the fracture toughness which depends upon the present state of crack tip stress, strength and geometry of the structural component. Material fracture toughness and the applied stress ratio influence the progressive damage and the fatigue life of concrete. This paper investigates analytically the progressive damage of concrete due to cyclic loading based on a stress intensity factor based fatigue damage prediction model. The effects of material property and specimen size have found to affect the propagation of cracks and the incremental damage. The varying sequence of cyclic loading has found to influence the progressive damage and fatigue life of concrete significantly.

Influence of aggregate size on flexural fatigue response of concrete

Plain concrete used in pavements undergoes fatigue damage with repeated traffic and thermal loading. Numerous studies were conducted previously to evaluate the effect of various parameters on the fracture behavior of concrete. Nominal maximum aggregate size which is one of the parameters investigated in the past, to evaluate the fracture characteristics was focused to influence the fracture energy of concrete significantly. This could be due to a larger crack path and greater crack growth resistance offered by the larger aggregates in the fracture process zone. Hence, it is worthwhile to investigate the effect of nominal maximum aggregate size (NMAS) of aggregate on the fatigue life of concrete. This factor, if influential, might be a feasible approach for field application to control the fatigue performance of concrete. In the present study, the effect of nominal maximum aggregate size was evaluated under different stress levels (80, 85, and 90%) and different frequencies of loading (2, 5, and 10 Hz). For this purpose, flexural fatigue test was conducted on concrete beam specimens. The specimens were prepared with a blend of fine aggregate and coarse aggregate with two different nominal maximum aggregate sizes (10 mm and 20 mm, designated as S10 and S20 respectively). A total of 100 specimens of 100 mm × 100 mm × 500 mm size were used in the experimental investigation. The results show that the fatigue life of samples with S10 mixture is significantly higher compared to S20 mixture for 80% stress level but are almost similar for 90% stress level irrespective of the loading frequency. The fatigue results are in better agreement with three-parameter Weibull distribution compared to other distributions such as lognormal as confirmed by the goodness of fit test Anderson-Darling statistic. The value of β, the Weibull distribution characteristic shape parameter, obtained as less than 1.0 in this study, indicates the risk of early life failures for the considered stress levels. The survival probability plots and p-value statistics suggest that stress level influences the fatigue life estimation for both S10 and S20 samples but not the loading frequency. Based on the present study, it can be concluded that smaller nominal maximum aggregate size is more beneficial for the fatigue performance of concrete.

Enhanced assessment rule for concrete fatigue under compression considering the nonlinear effect of loading sequence

In this paper, a refined engineering rule for the assessment of remaining fatigue life of concrete under compressive cyclic loading with varying amplitudes is proposed. The rule has been derived based on a combined numerical and experimental investigation of the loading sequence effect. The applied modeling approach is based on a damage model using the equivalent tensile strain rate to govern the fatigue damage evolution upon loading and reloading at subcritical load levels. A systematic calibration and validation procedure of the numerical model was performed based on the available experimental results. The prediction of the numerical model was compared with existing damage accumulation rules for the assessment of the concrete fatigue life exposed to varying loading ranges. Based on these studies, an enhancement of the Palmgren-Miner rule is proposed and validated for several loading sequence scenarios.

A probabilistic analyzed method for concrete fatigue life

In this manuscript, a novel analyzed method is proposed for stochastic analysis of concrete fatigue life. Starting from the material randomness and the typical fatigue damage accumulation behavior, a newly developed stochastic fatigue damage model (SFDM) is introduced to calculate the fatigue life. Then, a sensitivity analysis towards SFDM is carried out, based on which, the random model parameters representing the concrete fatigue mechanisms are verified. Based on the collected test data of different material strength levels, the probabilistic distributions of the random model parameters are identified, and these are used for the subsequent probabilistic analysis of concrete fatigue life. To implement the probabilistic analysis, a probability density evolution equation is developed by employing the probability density evolution method (PDEM). Through solving this equation, the probability density functions (PDF) of random concrete fatigue life and the corresponding mean and variance as well as their evolution with different loading levels are obtained.

THE FATIGUE DURABILITY OF THE MODIFIED ASPHALT CONCRETE UNDER THE EFFECT OF INTENSIVE TRAFFIC LOADS

Summary. The problem of prediction of the service life of asphalt concrete surface constructed with modified asphalt concrete application onto a traffic lane is examined. Asphalt concrete behaviour in road surface under the traffic loads was analysed. There were shown The results of experiments and their mathematical analysis of the assessment of standard and modified cold asphalt concrete fatigue life on road surface were shown. The service life of an asphalt concrete surface covered with standard and modified cold asphalt concrete is examined. The prediction has been received with an account of stress relaxation processes in asphalt concrete pavement and unevenness of traffic load application.

Uncertainty Analysis in Fatigue Life Prediction of Concrete Using Evidence Theory

Various sources of uncertainty exist in concrete fatigue life prediction, such as variability in loading conditions, material parameters, experimental data and model uncertainty. In this article, the uncertainty model of concrete fatigue life prediction based on the S-N curve is built, and the evidence theory method is presented for uncertainty analysis in fatigue life prediction of concrete while considering the epistemic uncertainty of the parameter of the model. Based on the experimental of concrete four-point bending beams, the evidence theory method is applied to quantify the epistemic uncertainty stem from experimental data and model uncertainty. To improve the efficiency of computation, a method of differential evolution is adopted to speedup the works of uncertainty propagation. The efficiency and feasibility of the proposed approach are verified through a comparative analysis of probability theory.

Mathematical Simulation of Concrete Fatigue Strength under Cyclic Loading

The problem of forecasting the durability of structures, buildings and constructions is one of the most urgent and important tasks in building sphere. In this paper, the authors propose a mathematical model of damage accumulation for the numerical simulation of the fatigue life of concrete. The results of numerical experiments with different levels of the applied load to the model are given, the fatigue characteristics of concrete material - Wohler curve - is built. On the basis of the developed method, the algorithm for research building designs using mathematical and physical modeling is formulated.

Fatigue Performance and Multiscale Mechanisms of Concrete Toughened by Polymers and Waste Rubber

For improving bending toughness and fatigue performance of brittle cement-based composites, two types of water-soluble polymers (such as dispersible latex powder and polyvinyl alcohol powder) and waste tire-rubber powders are added to concrete as admixtures. Multiscale toughening mechanisms of these additions in concretes were comprehensively investigated. Four-point bending fatigue performance of four series concretes is conducted under a stress level of 0.70. The results show that the effects of dispersible latex powder on bending toughness and fatigue life of concrete are better than those of polyvinyl alcohol powder. Furthermore, the bending fatigue lives of concrete simultaneously containing polymers and waste rubber powders are larger than those of concrete with only one type of admixtures. The multiscale physics-chemical mechanisms show that high bonding effect and high elastic modulus of polymer films as well as good elastic property and crack-resistance of waste tire-rubber powders are beneficial for improving bending toughness and fatigue life of cementitious composites.

Concrete Fatigue Life Characteristics of the Different Survival Rates in the Lateral Pressure Conditions

Under cyclic loading of concrete structures, fatigue failure is the main failure modes of fatigue, which has become the fatigue design of concrete structure must be considered, then the concrete fatigue studies must clarify the fatigue life of concrete under different survival curve S-N curve. Based on the statistics of the two parameter Weibull distribution theory, obtain the concrete under different survival rates of fatigue life distribution, namely to improve survival, reduce the fatigue life; stress level is reduced, the fatigue life is increased; and has set up more than 50% under different survival rates of concrete fatigue equation.

A Model to Predict Fatigue Life of Concrete Based on Total Strain Energy Density

A law on the cumulative damage is presented basing on total strain energy induced as damage parameter to calculate the cumulative damage when the specimens of concrete subjected to fatigue loading.Then the maximum of critical cumulative damage and location of production are determined basing on the equation of cumulative fatigue damage combined with experimental result through using the finite element analysis and the critical plane method in fatigue analysis.The relation equation between the standardized critical total strain energy density and stress level is obtained by considering the impact of loading level.The fatigue life of specimens can be predicted by combining the equation of cumulative fatigue damage with the relation equation of damage and stress level and the prediction results coincide with experimental results very well.

Two-Parameter Weibull Distribution Theory Testing Analysis in Fatigue Life of Asphalt Mixture

It has been commonly used normal distribution to describe the fatigue life of asphalt concrete. Because of the variability of the material itself and environmental conditions for test, experimental fatigue life datas obtained show a large discrete. Through a large number of laboratory tests and optimization of the strong representation of the data source, this paper verified distribution of the fatigue life of asphalt concrete in statistical in the use of two-parameter Weibull distribution theory and obtained fatigue life equation by regression under different failure probability.The results showed that: Weibull distribution theory can be used to describe asphalt concrete fatigue life distribution under the complicated conditions in a multi-factor.

Experimental and numerical investigations on fatigue damage propagation and life prediction of high-performance concrete containing reactive mineral admixtures

The effects of reactive mineral admixtures (fly ash and ground slag) on damage propagation and fatigue life of concrete are deeply investigated by experiments and numerical simulations based on high-resolution digital images of the actual concrete microstructure. Four-point bending experimental fatigue tests are performed, where the evolution of the damage is followed using a real-time detection method. The initiation and propagation of micro-cracks and fatigue damage of concrete are predicted by the improved lattice model, and the modeling results are consistent with the experimental ones. Furthermore, the modeling and experimental results show that, by adding fly ash and ground slag to concrete, the fatigue crack propagation and damage accumulation under high/low stress levels change with respect to those related to concrete without admixtures, and the fatigue behavior of the material with such admixtures improves.

Real-time Detection and Analysis of Damage in High-performance Concrete under Cyclic Bending

In order to quantitatively evaluate the damage level in high-performance concrete (HPC) with pozzolanic minerals under constant amplitude cyclic loads, three methods for real-time damage detection are employed in the present work, i.e., dynamic modulus instrument, real-time strain collector, and digital speckle correlative method (DSCM). Six mechanical parameters at different numbers of loading cycles are real-time captured by these three methods. For a maximum applied fatigue stress equal to 70% of the static flexural strength, a cohesive crack is detected on the specimen surface by the DSCM system from 10% of concrete fatigue life. The nucleation and propagation of the cohesive crack is reflected by the change of the strain concentration zone in 2-dimensional strain fields. The experimental results show that the admixtures of Class F Fly Ash (FA) and S95 Ground Granulated Blast-furnace Slag (GGBS) in high proportions increase the strain and cohesive-crack opening displacement as well as remarkably improve the fatigue performance of HPC.

Laboratory Testing Material Property and FE Modeling Structural Response of PAM-Modified Concrete Overlay on Bridges

Portland cement concrete overlay on bridge deck is subjected to distresses of cracking and interface debonding under the effects of repeated vehicle loading and temperature cycling. In order to improve the overlay performance, this research used the polyacrylamide (PAM) polymer to modify the mechanical properties of concrete. The direct shear and impact resistance tests were designed to measure the interface bonding strength and dynamic performance, respectively. The comprehensive and flexural strength and three-point bending fatigue tests were conducted following the standards. Meanwhile, the three-dimensional finite-element (FE) models of the T-girder and box-girder bridges under the moving traffic loadings were built to analyze the stress response and improve the structural design. An analytical model of flexural stress was developed and validated the FE modeling results. A rubber cushion was designed in the FE model to “absorb” the flexural stress. Laboratory testing results indicate that PAM can significantly improve the flexural strength, bonding strength, impact resistance, and fatigue life of concrete. The modified concrete with 8% PAM by mass of cement poses higher flexural strength and impact resistance than concretes with other PAM percentages. FE simulation results indicate that there exists a critical overlay thickness inducing the maximum interface shear stress, which should be avoided in the structural design. The rubber cushion can effectively relieve the flexural stress.

Statistical Analysis for Fatigue Life of Concrete

Statistical analysis is presented for 108 groups of fatigue test data of concrete, including tests of abnormal value, variance and distribution-fitted with fuzzy optimization; analysis of variance, sample size and error. It is chiefly concluded that effect of stress level of repeated loading on the fatigue life of concrete is much more significant than that of stress rate and relative stress amplitude, and effect of stress rate and relative stress amplitude are of the same significance; Relationship of sample size, relative error and significant level is also presented; fatigue life of concrete is more fitted for lognormal distribution than Weibull distribution. Suggestion for relevant code, standard and regulation are presented.

A distribution function for the fatigue life of concrete

The fatigue life distribution of concrete under repeated loading with random excitation is scattered. Thus it is desirable to use an uncertainty measure such as probability in the analysis of concrete fatigue life. This Paper, based on a fatigue damage mechanism analysis, considers the fatigue damage development process of concrete to be a Markov process. A new distribution function is given for the damage at a given time which can also predict the life distribution if the critical damage is given. By comparison with test results, it is shown that this new distribution is sufficiently flexible to fit test data.

変動繰返し荷重下におけるコンクリートの疲労特性に関する研究

In order to understand the effects of various factors on fatigue life of concrete under varying repeated load, two-stage and three-stage stress fatigue tests were performed. As the factors, the order of repeated loads, the number of cycles in initial stress level (S1) n1, and the following stress level S2, S3 were selected. Since the values of fatigue life of concrete are known to scatter widely, the fatigue test results were evaluated statistically.The experimental results show the followings:(1) The sum of cycles ratio for the same test condition follows a logarithmic normal distribution.(2) The estimation of fatigue life with Miner's rule predicts on the unsafety side when the initial stress level is higher than the following stress level.(3) The Miner's rule, however, may be applicable for the prediction of fatigue life of concrete under varying repeated load when the order of repeated load is uncertain.