Multi-axle Loads Research Articles

Evaluation of equivalent axle load factors for multi axles based on fatigue tests using actual strain waveforms

Equivalent axle load factor (EALF) is used to characterize the fatigue damage effect of multi-axle loads on asphalt pavement. EALF is calculated as the ratio of the pavement’s fatigue resistance under a single axle load to that under a multi-axle load. Existing studies use the same fatigue life function to predict the fatigue life of asphalt mixture under both single- and multi-axle loads, primarily focusing on the differences in pavement strains under these two configurations. However, strain waveforms in asphalt pavement caused by multi-axle loads differ from those under single-axle loads, altering the mixture’s fatigue behavior. To address this issue, this research tests the fatigue responses of asphalt mixtures under actual loading waveforms from single-axle, tandem-axle, and tridem-axle loads. Based on the test results, fatigue life functions are developed for each axle configuration and used to establish an updated EALF model. Since the applied fatigue life functions are based on test results from more realistic strain waveforms, the calculated EALFs provide more reliable predictions of the damaging effect of multi-axle loads on asphalt mixtures.

Minimum variance unbiased Bayesian smoothing for input and state estimation of systems without direct Feedthrough: Mitigating Ill-Posedness of online load identification

In this paper, the problem of moving load identification using pure displacement measurements is addressed. It is known that when no assumptions are made on the statistics of the unknown loads and a minimum variance unbiased (MVU) estimation approach is adopted, the existing methods in the literature suffer from a very elevated load estimation uncertainty. This elevated uncertainty is due to ill-posedness of the problem. In this paper a new method is proposed that addresses this issue via an MVU smoothing approach. To alleviate this problem, a MVU smoothing algorithm is proposed in this study, via modification of a MVU smoothing Bayesian estimator proposed by some of the co-authors of this paper hence referred to as MSBE, which leads to substantial decrease in the moving load estimation uncertainties using pure displacement measurements. The efficacy of the MSBE is studied through a simulated experiment corresponding to a numerical model of an operating steel railway bridge with riveted connections and a multi-axle load. The selection of the hyperparameters of the smoothing and filtering techniques are discussed, and the optimal values are presented. The parametric studies show that the proposed method can yield highly accurate results, and substantially outperforms a celebrated MVU filter proposed by Gillijns and De Moor.

Research of multi-axles effects on the flexible pavement based on the viscoelastic continuum damage model

Damages caused by the multi-axles load on the pavement are more complex, due to the interaction between axles. To investigate influences of the multi-axles load on the bottom-up crack of the flexible pavement, the equivalent factor (EF) that represents damage ratios of multi-axles to single-axle based on the viscoelastic continuum damage model was proposed. Through the finite element method, influences of temperature, pavement thickness, and axle configuration on the EF were analyzed. Results suggest that the asphalt mixture with smaller m-value is more likely to have smaller EF. With the increase of temperature and asphalt layer thickness, EF of dual-axles load increases but EF of triple-axles load decreases. Besides, the wheelbase is the only factor of the axle configuration that has remarkable impacts on the EF. Making the distance between the maximum compressive and tensile stress close to the wheelbase can reduce the damage of multi-axle load.

Different Analysis of Rigid Pavement Subjected to Multi Axle Load and Temperature Effect

In this study the axle load studies are carried out to determine actual load of each axles on the road surface. In the present study, Static Weighing method is used for the axle load survey. The Sample size of the axle load survey is determined by conducting Classified Volume Survey as per IRC: 58 – 2015. Axle load Spectrum is generated with the help of axle load study. Based on the Axle load survey and Warping stress, stress – deflection analysis is done with the help of Westergaard Theory, IRC-58 (2015) and ANSYS software. Results which are analysis by Ansys is closed to Westergaard theory and IRC – 58 (2015) In the present study, stretch Kankot to Vavdi, near Punitnagar, Rajkot is selected for the analysis study.

Response Characteristics of Inverted-base Asphalt Pavement Structure in Cold Area under Multi-axle Loads

In cold areas, semi-rigid base asphalt pavement is prone to generate reflection cracks due to thermal contraction and dry shrinkage, and the base layer cracks can cause surface layer cracking and shorten the service life of the pavement. Aiming at understanding the response characteristics of asphalt pavement structure under multi-axle loads in cold areas, this paper took semi-rigid base asphalt pavement and inverted-base asphalt pavement as the research objects, and employed ANSYS to conduct finite element analysis on them to figure out the response characteristics of the asphalt pavement structure under the condition of different multi-axle loads and graded macadam base course. The research results showed that, the action of multi-axal loads increased the tensile stress of the base layer of the asphalt pavement and the tensile stress of the base layer of the semi-rigid base asphalt pavement, and increased the road surface deflection, which had resulted in insufficient bearing capacity of the pavement structure, and thus causing significant damages to the asphalt pavement; analysis of the response characteristics of the two types of asphalt pavement showed that, adding a graded macadam base course as the stress-absorbing layer is conductive to reducing the tensile stress of the base layer of the semi-rigid base asphalt pavement and effectively delaying or inhibiting reflection cracks generating on the pavement. The study of this paper provided a theoretical reference for the design and construction of asphalt pavement.