Design Fatigue Lives of Polypropylene Fibre Reinforced Polymer Concrete Composites

Flexural fatigue behavior of Poly-propylene fibre reinforced polymer concrete composites (PFRPCC) has been investigated at various stress levels and the statistical analysis of the data thus obtained has been carried out. Polymer Concrete Composite (PCC) samples without addition of any type of fibres were also tested for flexural fatigue.  Forty specimens of PCC and One hundred and Forty One specimens of PFRPCC containing 0.5%, 1.0% and 2.0% polypropylene fibres were tested in fatigue using a MTS servo controlled test system. Fatigue life distributions of PCC as well as PFRPCC are observed to approximately follow a two parameter Weibull distribution with correlation coefficient exceeding 0.9. The parameters of the Weibull distribution have been obtained by various methods. Failure probability, which is an important parameter in the fatigue design of materials, has been used to obtain the design fatigue lives for the material. Comparison of design fatigue life of PCC and PFRPCC has been carried out and it is observed that addition of fibres enhances the design fatigue life of PCC

Aging concrete structures: a review of mechanics and concepts

The safe and cost-efficient management of our built infrastructure is a challenging task considering the expected service life of at least 50 years. In spite of time-dependent changes in material properties, deterioration processes and changing demand by society, the structures need to satisfy many technical requirements related to serviceability, durability, sustainability and bearing capacity. This review paper summarizes the challenges associated with the safe design and maintenance of aging concrete structures and gives an overview of some concepts and approaches that are being developed to address these challenges

Fatigue Analysis of High Performance Cement Concrete for Pavements Using the Probabilistic Approach

Cement concrete pavements are designed for flexural fatigue loading due to traffic. Due to its numerous advantages high performance cement concrete is finding it’s way in pavement construction. This paper investigates the fatigue strength of High Performance Cement Concretes subjected to flexural loading. Fatigue studies are conducted on these concretes to obtain the fatigue lives at various stress levels. Static flexural strength tests are conducted to determine the static failure loads on prism specimen. From the experimental studies carried out, the number of load repetitions to failure on the concretes under study is determined for three stress ratios. From the data obtained S-N curves are developed using linear regression models considering log normal distribution as is being presently adopted. Recent literature shows that weibull distribution is found to have more convincing physical features than the lognormal distribution to describe the fatigue behavior o concrete. To incorporate the probability of failure, weibull distribution is considered and Pf-S-N diagram are developed. It is observed that addition of fly ash and silica fume improves the fatigue performance of concrete by48% and 83% at a stress level of 0.75

A Report of the Investigation on Steel Bridge Design Criteria to Help Minimize the Probability of Fracture; Project IHR-304, Illinois Cooperative Highway Transportation Research Program

In this study the nature of actual random traffic stress histories in steel beam or girder highway bridges has been investigated. Quantitative field test results have been used to develop mathematical models that can be used to represent the stress histories for such bridges. The beta distribution function has been found to be an effective mathematical model for the actual stress-range histograms and has been used to establish random stress factors and can be used in fatigue design to account for the random nature of loadings in highway bridges.State of Illinois. Department of TransportationU.S. Department of Transportation. Federal Highway Administratio

Aeronautical engineering: A continuing bibliography, supplement 122

This bibliography lists 303 reports, articles, and other documents introduced into the NASA scientific and technical information system in April 1980

Comparison of alternatives to amplitude thresholding for onset detection of acoustic emission signals

Acoustic Emission (AE) monitoring can be used to detect the presence of damage as well as determine its location in Structural Health Monitoring (SHM) applications. Information on the time difference of the signal generated by the damage event arriving at different sensors in an array is essential in performing localisation. Currently, this is determined using a fixed threshold which is particularly prone to errors when not set to optimal values. This paper presents three new methods for determining the onset of AE signals without the need for a predetermined threshold. The performance of the techniques is evaluated using AE signals generated during fatigue crack growth and compared to the established Akaike Information Criterion (AIC) and fixed threshold methods. It was found that the 1D location accuracy of the new methods was within the range of <1–7.1%<1–7.1% of the monitored region compared to 2.7% for the AIC method and a range of 1.8–9.4% for the conventional Fixed Threshold method at different threshold levels

Probabilistic lifetime assessment of RC structures under coupled corrosion-fatigue deterioration processes

International audienceStructural deterioration is becoming a major problem when considering long term performance of infrastructures. The existence of a corrosive environment, cyclic loading and concrete cracking cause structural strength degradation. The interaction of these conditions can only be taken into account when modeling the coupled action. In this paper, a new model to assess lifetime of RC structures subject to corrosion-fatigue deterioration processes, is proposed. Separately, corrosion leads to cross section reduction while fatigue induces the nucleation and the propagation of cracks in steel bars. When considered together, pitting corrosion nucleates the crack while environmental factors affect the kinematics of crack propagation. The model is applied to the reliability analysis of bridge girders located in different chloride-contaminated environments. Overall results show that the coupled effect of corrosion-fatigue on RC structures affects strongly its performance leading to large reduction in the expected lifetime

Aeronautical Engineering. A continuing bibliography, supplement 115

This bibliography lists 273 reports, articles, and other documents introduced into the NASA scientific and technical information system in October 1979

Flexural Fatigue Analysis of Concrete made with 100% Recycled Concrete Aggregates

The paper presents results of an investigation to study the flexural fatigue performance of concrete beams made with 100% Coarse Recycled Concrete Aggregates (RCA). Experimental investigation has been carried out to obtain the flexural fatigue lives of concrete beam specimens of size 100 × 100 × 500 mm at various stress levels under four point flexural fatigue loading. The test data is used to plot the S-N curves and a simple regression analysis is used to propose an equation to estimate the flexural fatigue strength of concrete made with 100% RCA. The flexural fatigue performance of concrete made with 100% RCA has been assessed in terms of its mean and design fatigue lives. Two million cycles fatigue strength/endurance limit has also been estimated and compared with the previous studies available on Natural Aggregates (NA).