Study of Influence of Operating Parameters on Braking Distance

Stopping distance includes driver thinking distance and braking distance. Braking distance is one of the basic standards for road design and maintenance practices. Adequate tire–pavement skid resistance plays a significant role in reducing braking distance and consequently enhancing road safety. With technology such as the antilock braking system, the friction force is maximized by applying the brakes repeatedly, in an on-and-off pattern, such that the braking distance is shortened. Several studies have shown the effect that some parameters, such as water film thickness, tire inflation pressure, and wheel load, have on braking distance. Less discussed is the effect of slip ratio, temperature, and pavement surface characteristics. Measuring the braking distance in the field is energy-consuming and time-consuming, and there are uncertainties in the environmental conditions as well. General approaches to calculating braking distance are based on basic mechanics principles. To the authors’ knowledge, a model that can simulate the whole braking process is not available. The presented study proposes a way to predict braking distance by means of finite element modeling only. A model that can include the effect of parameters such as temperature, slip ratio, and pavement surface characteristics on the braking distance is introduced.Accepted Author ManuscriptPavement Engineerin

Towards an understanding of the self-healing capacity of asphaltic mixtures

The self-restoring or healing capacity of asphalt has been known for quite some time. Yet, to this date, there is no consensus of the fundamental mechanism underlying this phenomenon. In this paper a multi-scale model is presented which focuses on the healing phenomenon from a thermodynamic point of view. In the model, healing of bituminous material is simulated at the micro scale via a phase field model, utilizing a modified version of the Cahn Hilliard and Flory-Huggins equations. This model is then connected to a more general elasto-visco-plastic constitutive framework for the simulation of asphalt mixtures. The paper presents the developed hypothesis, the experimental evidence and summarizes some of the theoretical background. The model has been implemented in the 3D finite element system CAPA-3D and preliminary results are shown

Experimental study of membrane fatigue response for asphalt multisurfacing systems on orthotropic steel deck bridges

In order to adequately characterize the fatigue response of the various membranes with surrounding multilayer surfacing layers on orthotropic steel decks and collect the necessary parameters for FE modeling, the details of the cyclic Membrane Adhesion Tester (MAT) are introduced. The fatigue damage in membrane interface is related to the amount of dissipated work computed by using the measurement of actuator load and piston deformation during the loading cycle. The dissipated work, which is equivalent to the lost part of the total potential energy of the membrane, has been utilized to explain the incremental damage during the testing. Furthermore, using the experimental data obtained from MAT, ranking of the bonding characteristics of various membrane products is demonstrated as well as the role of other influencing factors, such as the types of substrate and test temperatures.Structural EngineeringCivil Engineering and Geoscience

The Influence of Air Void Content on Moisture Damage Susceptibility of Asphalt Mixtures: A Computational Study

Because of the difficulties associated with the generation of finite element meshes based on X-ray computed tomography scans and with the extraordinary computational demands in performing three-dimensional (3-D) finite element analyses, past modeling efforts have focused primarily on two-dimensional representations of asphalt mixtures and have placed no emphasis on the inclusion of the air voids network in the body of an asphalt concrete specimen. A 3-D micromechanical moisture damage model has been developed and implemented in the finite element system CAPA-3D capable of addressing individually the three main phases of asphalt concrete: aggregate, mastic, and air voids. The 3-D finite element meshes of different types of asphalt mixtures were generated on the basis of X-ray scans. By means of CAPA-3D, the significance of the air voids structure in the development of moisture damage in asphalt concrete specimens was demonstrated. Availability of the model enables evaluation and ranking of the contribution of the characteristics of the individual mixture components to the overall mixture moisture resistance.Structural EngineeringCivil Engineering and Geoscience

Finite Element Studies of Skid Resistance under Hot Weather Condition

The skid resistance of a pavement surface is an important characteristic that influences traffic safety. Previous studies have shown that skid resistance varies with temperature. However, relatively limited work has been carried out to study the effect of temperature on skid resistance in hot climates. Recent developments in computing and computational methods have encouraged researchers to analyze the mechanics of the tire-pavement interaction phenomenon. The aim of this paper is to develop a thermo-mechanical tire pavement interaction model that would allow more robust and realistic modeling of skid resistance using the Finite Element (FE) method. The results of this model were validated using field tests that were performed in the State of Qatar. Consequently, the validated FE model was used to quantify the effect of factors such as speed, inflation pressure, wheel load, and ambient temperature on the skid resistance/braking distance. The developed model and analysis methods are expected to be valuable for road engineers to evaluate the skid resistance and braking distance for pavement management and performance prediction purposes.Pavement Engineerin

Test method to assess membrane layers fatigue response on orthotropic steel bridge decks

In order to adequately characterize the fatigue response of the various membranes with surrounding multilayer surfacing layers on orthotropic steel decks and collect the necessary parameters for FE modeling, the details of the cyclic Membrane Adhesion Tester (MAT) are introduced. The fatigue damage in membrane interface is related to the amount of dissipated work computed by using the measurement of actuator load and piston deformation during the loading cycle. The dissipated work, which is equivalent to the lost part of the total potential energy of the membrane, has been utilized to explain the incremental damage during the testing. Furthermore, using the experimental data obtained from MAT, ranking of the bonding characteristics of various membrane products is demonstrated as well as the role of other influencing factors, such as the types of substrate and test temperatures.Structural EngineeringCivil Engineering and Geoscience