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Although Friberg's theoretical analysis is frequently used to analyse the dowel bar-concrete interaction in jointed plain concrete pavement (JPCP) system, the compressive stress concentration at top and bottom of the dowel slot cannot be explained with this theory. In this paper, two modifications including the elastic deformation of concrete support and the stress distribution factor considering the sinusoidal contact stress distribution are proposed to improve the Friberg's theoretical analysis. Modifications are then validated against elastic finite element analysis (FEA) results in terms of the contact stress distribution, the maximum compressive stress as well as the range of compression zone. To further investigate the maximum compressive stress at the joint surface, relevant parameters including the dowel bar diameter, the modulus of elasticity of concrete as well as the joint width are studied through elastic finite element analysis (FEA). Apart from proposing referenced moduli of dowel support, a close relationship between the modified modulus of dowel support and dowel bar diameter is also found and verified. Finally, differences between the Friberg's theoretical analysis and the modified method are summarised in a flow chart at the end of the paper. [ABSTRACT FROM AUTHOR]

The effect of temperature on the meso-mechanical properties of each structural layer of the pavement was studied in this paper. Fitting standard indoor uniaxial compression tests, meso-scale parameters of the material were obtained. With the mesoscopic parameters of each structural layer, a two-dimensional discrete element model of the pavement was constructed. This discrete element model of the road surface was coupled with the 2 DOF 1/4 vehicle model, and the unevenness of the road surface provided incentives for vehicles. At different temperatures, the meso-mechanical response of each structural layer of the road surface was solved under the action of vehicle loads. The movement of particles at different temperatures was analysed. The results show: compared with the finite element model, the vertical displacement produced by the discrete element model is 4.8% larger than the finite element model. That shows that the discrete element model data has certain credibility. The vertical displacement decreases as the depth of the structural layer increases and increases as the road surface temperature increases. And the vertical stress decreases as the depth of the structural layer increases, and increases as the road surface temperature increases. The horizontal stress of the upper layer is compressed, the horizontal stress of the lower layer is stretched, and the horizontal stress of the remaining structural layers does not change significantly. The horizontal stress decreases as the road surface temperature increases. The tangential stress of each structural layer is in anti-symmetric state, both tensile state and compressed state. Tangential stress decreases with increasing road surface temperature. The higher the temperature, the smaller the tangential stress. The effect of temperature on the velocity of particles in the early stage is greater than that in the late stage. [ABSTRACT FROM AUTHOR]

The adhesive bonding strength of the membrane layers between the asphalt concrete surface layers and the decks of steel bridges has a strong influence on the fatigue life of orthotropic steel deck bridges (OSDBs). The interfacial properties between the membrane and the layers bonded to it have not been extensively studied in the current orthotropic steel deck bridge system. For the adequate characterisation of the adhesive-bonding strength of various membranes and surrounding materials on OSDBs and for the collection of the necessary parameters for finite element model, details of the membrane adhesion test (MAT) are introduced and simulated by using the adhesive traction-separation interface element which was developed in a companion paper to this contribution (Liu, X., Kasbergen, C., Li, J., & Scarpas, A. (2019). Modelling of membrane bonding response: part 1 development of an adhesive contact interface element. International Journal of Pavement Engineering). Parametric studies of the adhesive contact element utilised for modelling the membrane bonding layer in the MAT test have been performed on the basis of the combination of different critical strain energy release rates and the characteristic opening length in the constitutive model. Comparison of membrane deformation profiles and the in-time debonding force distribution between experimental observations and finite element simulations have been presented. [ABSTRACT FROM AUTHOR]

This paper presents a new approach for calibration of Mechanistic-Empirical Pavement Design Guide (MEPDG) permanent deformation models using the Hamburg Wheel Rut Tester (HWRT) Data. The approach was applied on two Ontario mixes tested in HWRT to calibrate and validate the asphalt concrete (AC) rut models. Data from one Long-Term Pavement Performance (LTPP) programme test section in Ontario were also used for verification, calibration and validation of the AC and unbound pavement layer rut models. The section had two construction (CN) life spans, one before milling and overlay (CN1) and one after (CN2). The study used two finite element models and an Excel VBA sheet to run the verification, calibration and validation of the MEPDG rut models. Proposed calibration coefficients resulted in significant reduction in bias, sum of squared errors (SSE) and standard error of estimate (SEE) for rutting by at least 91% for the two HWRT mixes and by at least 67% for CN1 and CN2, when compared with the global and Ontario local calibration coefficients. The results support the conclusion that the approach of using laboratory wheel tracking device data for calibrating the MEPDG rut models is promising. [ABSTRACT FROM AUTHOR]

Over the recent years, considerable attention has been drawn to intelligent driving technologies and particularly to automated vehicles (AVs). The deployment of AVs would provide the opportunity to have more control over the dynamics of the vehicle, including its lateral movement, which can affect the pavement's long-term rutting performance. The controlled lateral movement of the AVs may also imply a reduced lane width. This paper evaluates the impacts of dedicating a reduced lane width to AVs on pavement rutting performance, considering two lateral movement modes for AVs; zero-wander and uniform-wander. A finite element model was developed using ABAQUS software. The rutting simulation results of this study showed that the abrupt changes in the loading schemes of the zero- and uniform-wander modes cause considerable accumulated rutting in the edges of the loading areas. This is significantly greater than the total rutting induced by the human-driven vehicles (HDVs) following the normal-wander mode, which causes a compensated rutting behaviour by a gradual increase in loading time. Furthermore, the comparison between rutting depths in different lane widths reveals that when dedicating the narrower lane for AVs with a uniform-wander distribution, the pavement's total rutting depth would remarkably increase compared to the wider lanes. [ABSTRACT FROM AUTHOR]

In this paper, the dynamic response of an axisymmetric transversely isotropic medium with its modulus varying with depth subjected to the lightweight deflectometer (LWD) load is calculated by an analytical solution method. In this model, the analytical solutions are expressed as power series, and both cases of vertical modulus, increasing and decreasing with depth, are considered. This study can be divided into three key steps. Firstly, the ordinary differential equations are obtained via the Hankel–Laplace transform, and the general solutions of dynamic response are obtained according to the Frobenius method. Secondly, combined with the boundary conditions, the dynamic responses of the subgrade in the time domain are calculated. The accuracy and reliability of this dynamic model are proved by parameter convergence analysis, finite element method and comparison validation. Lastly, the effect of thickness, non-uniform distribution of modulus and transverse isotropy subjected to LWD load are analysed and discussed. The calculation methods and the corresponding results are meaningful for the design and non-destructive monitoring of the subgrade. [ABSTRACT FROM AUTHOR]

Traditional jointed plain concrete pavement (JPCP) systems cannot be reused after grouting fast-setting materials in the dowel slot. To achieve demountability, a removable dowel bar connection system is proposed in this paper. The severe stress concentration occurring in JPCP systems is mitigated by applying a stainless steel ring at the pavement joint surface. In the monotonic loading tests, different stainless steel ring thicknesses, lengths and the stainless steel tube thicknesses were considered. The effect of the stainless steel ring on the structural performance of the removable dowel bar connection system was studied in terms of the failure mode, the deflection response, ductility and the strain distribution and development. Besides, after being validated against experimental test results, the developed finite element model was used to conduct the extended parametric analysis, in which a close relationship was found between the ultimate load and the stainless steel ring length. To prevent the localised crushing failure, the maximum compressive stress at the joint surface was compared with the allowable bearing stress under service load. By using FEA data, an empirical equation was finally proposed to predict the ultimate loads of specimens with the proposed connection system. [ABSTRACT FROM AUTHOR]

Paris' power law is commonly used to describe transverse thermal cracking propagation in asphalt concrete (AC) pavements. In its most common format, it relates the rate of change in the crack length per cycle to changes in either the stress intensity factor K or the energy release. The parameters defining this relationship for ACs can be obtained using the Texas cyclic Overlay Test (OTR). This paper describes two numerical approaches for simulating the OTR using the extended finite element method (XFEM). The first uses the direct low-cyclic fatigue (LCF) approach and the second uses the virtual crack closure technique (VCCT). Comparisons of the model predictions to laboratory OTR measurements for six mixtures suggest that the XFEM model coupled with VCCT is better suited for simulating the OTR. The model output includes the crack length and the energy release rate ERR (i.e. ${\rm \Delta }J_R$ Δ J R ) as cracks propagate. This data was used to fit the modified Paris' law parameters ${A}^{\prime}$ A ′ and ${n}^{\prime}$ n ′ as a function ${\rm \Delta }J_R$ Δ J R . Subsequently, the traditional A and n Paris' power law parameters were fitted by estimating the corresponding ΔK. Using this model, it was possible to efficiently estimate the AC cracking parameters using as input only the tensile modulus and the critical ERR. [ABSTRACT FROM AUTHOR]

In this paper, the wheel track areal distribution of a short takeoff and landing aircraft was tested by using the self-developed airport pavement wheel track test system. The transverse and longitudinal distribution regulations of the wheel track of single-aircraft takeoff, dual-aircraft takeoff and landing were statistically analyzed, and the coverage of each point on the pavement were obtained. The joint simulation of MATLAB and ABAQUS was utilised to realise the fast calculation of the stress state at each point of the pavement. The longitudinal load of the pavement calculated based on the six-degree-of-freedom aircraft taxiing model was substituted into the finite element model, and the allowable coverage at each point on the pavement was calculated combined with the fatigue equation of concrete. Furthermore, an airport pavement design method based on the cumulative damage areal distribution was proposed, which could provide damage characteristics at any point on the pavement. The case analysis shows that the thickness of pavement within 600 m at both ends of the pavement for Aircraft A can be designed as 22 cm, and that of the middle pavement can be designed as 19 cm. [ABSTRACT FROM AUTHOR]

In this study, the plastic coupled cohesive model and enhanced virtual crack closure technique (VCCT) are used to investigate the fracture behaviour of the basalt fibre reinforced asphalt concrete (BFRAC). In the plastic coupled cohesive model, the separation and traction response along the cohesive zone advance ahead of a crack tip is governed by an exponential cohesive law. The double-K fracture theory is integrated into the enhanced VCCT model. It is shown that the simulated load-cracking mouth opening displacement (P-CMOD) curves from both the plastic coupled cohesive model and the enhanced VCCT model compares favourably with the measured curves from the single-edge notched beam. The parameters used in the plastic coupled cohesive model cannot directly be obtained from the standard test, and the inverse analysis method is always necessary for identifying the fracture parameters. On the contrary, the fracture parameters in the enhanced VCCT method can be directly calculated from the P-CMOD curves based on the double-K fracture theory and the finite plastic fracture theory (Hutchinson, Rice, Rosengren singular crack tip fields, abbreviated as HRR field). Meanwhile, compared with the plastic coupled cohesive model, the enhanced VCCT model coupled with the Ramberg–Osgood elasto-plastic harden model is promising for investigating the physical mechanism underlying the nonlinear fracture of BFRAC. This paper proposed two concrete and valuable models in the finite element method for simulating the fracture behaviour of the huge structure with asphalt and asphalt concrete. [ABSTRACT FROM AUTHOR]

This paper presents a virtual generation method for the heterogeneous microstructure of asphalt mixtures. The coarse aggregates used in the digital asphalt mixture were derived from real aggregates captured by a three-dimensional (3D) laser scanner. Then, a rigid-body dynamic simulation framework was proposed to generate a stable skeletal structure composed of coarse aggregates similar to those formed by compaction. Furthermore, FAM and air voids were generated based on the generated aggregate skeleton and the assumption of equal thickness of FAM film. To prove the reliability of the model, the air voids of the digital asphalt mixture samples were verified by comparison with real specimens. The generated digital specimens were also applied to finite element method (FEM) simulations to predict the dynamic modulus of the asphalt mixture and the simulated results were in good agreement with the experimental results. The method can be applied to study the spatial distribution of asphalt mixture components, the movement pattern of aggregate particles during compaction and numerical simulations at the microscopic scale. [ABSTRACT FROM AUTHOR]

Accurate monitoring of concrete pavement support condition is critical for pavement maintenance. This paper proposed a novel support condition monitoring method using distributed optical fiber sensing (DOFS) technology. The DOFS-based method can precisely monitor the support condition on a larger scale. Single-mode optical fiber with a particular rubber encapsulation was applied as a compression sensor, measuring the interfacial compression status between the concrete pavement slab and the pavement base through a compression-to-strain transfer mechanism. Finite element analysis (FEA) and laboratory experiments were conducted to compression-to-strain transfer mechanism. It was revealed that the average compression-to-strain transfer efficiency reached over 1900 μϵ/mm. The design parameters of the compression sensor were also provided based on the FEA and experiment results. A quasi-distributed sensing system was developed to capture the two-dimensional support condition by connecting the sensors in a particular path. The sensing system's effectiveness was demonstrated by conducting full-scale tests and using the pressure-sensitive film (PSF) as a comparison. The test results showed a great deal of applicability for support condition monitoring under concrete pavement. [ABSTRACT FROM AUTHOR]

This paper quantifies the relevance of restriction to joint rotation of an airfield concrete pavement when calculating critical curling stresses and deflections using a validated finite element model. The validation uses strains measured at the John F. Kennedy International Airport. To calculate critical curling stresses and deflections, the pavement was subjected to 5263 h of temperature variation determined by utilising the enhanced integrated climate model and thermocouple readings. The profiles include a wide range of average temperatures, temperature gradients, and temperature nonlinearity. Three conditions were included: (1) joints free to displace and rotate; (2) joints free to rotate, but partially restrained to vertical displacement; and (3) joints partially restrained to vertical displacement and rotation. Differences in critical stresses between the second and third conditions were greater than 5% for 70% of the time. When considering rotational restriction, critical deflections are reduced. Eighty percent of the difference, with respect to the free case, was caused by rotational restriction. It was evident that joint rotation intensifies the influence of curling stresses and deflections on long-term performance of airfield rigid pavement. [ABSTRACT FROM AUTHOR]

The rutting resistance design of asphalt pavement is full of compromise between technology and economy because it is difficult to predict rutting evolution and distribution. In order to investigate the criterion of rutting, two forms yield function based on the Perzyna theory were contrasted and utilised in the finite element model. Besides, temperature and traffic load, the most important factors of rutting, were taken into consideration to make the analysis of yield function closer to the field condition of pavement. Two resistance points were proposed as criterions in this paper. One can be used in pavement maintenance to figure out the depth of serious rutting, the other can be used in pavement design to determine the usage depth of modified asphalt mixture. The analysis illustrates that the key to controlling rutting at intersections is to use better anti-rutting materials at the top layers instead of deepening the usage of modified asphalt mixture. Besides, the depth of rutting varies dramatically with axle weights. It can be inferred that there may be deviations of the prediction for the rutting distribution and evolution when using the method of equivalent axle weight. [ABSTRACT FROM AUTHOR]

This paper used the finite element method to analyse surface water distribution characteristics on porous asphalt layer under unsaturated seepage, and further compared the critical rainfall intensity of porous asphalt pavements with different design parameters. In this study, the Richards equation was used to describe the unsaturated seepage, and the results were validated with experimental data. The results show that when the water accumulates on the pavement surface, it would firstly emerge at the lowest level of pavement along the longitudinal direction, and then spread along transverse and longitudinal directions. The water depth has no remarkable difference along the longitudinal direction while it differs a lot among different transverse positions. The distribution of surface water depth was analysed and the correlation between the surface water coverage in the transverse direction and the rainfall intensity was established with high R-square values. For pavements with different geometries, the porous layer thickness has the most remarkable effect on the critical rainfall intensity of porous asphalt pavements. [ABSTRACT FROM AUTHOR]

This study systematically investigates the effect of microcracking on the shrinkage performance and durability of cement-treated macadam (CTM). Microcracks formed in the early stage of microcracking can reduce reflection cracks generated in semi-rigid base asphalt pavements. The shrinkage characteristics and durability of CTM after microcracking are important to consider in the engineering of the CTM base. In this study, indoor shrinkage tests were conducted on the prepared specimens in ten working conditions, and finite element analysis of the water loss shrinkage of the microcracked CTM was conducted using a cohesive zone model (CZM). The CTM durability after early microcracking was analyzed and evaluated through fatigue tests and freeze–thaw cycle tests. The results showed that the drying shrinkage strain and temperature contraction coefficient of the CTM could be effectively reduced by microcracking. The fatigue life of the CTM decreased with 50% microcracking, but was still within the service requirement. Taking the 104 Chinese road reconstruction project as the research background, microcracking should be conducted 35 d before the freezing period to avoid significantly affecting the frost resistance of the CTM base. This study provides a theoretical basis for the promotion and application of microcracking techniques in practical engineering. [ABSTRACT FROM AUTHOR]

Skid-resistance performance of a runway greatly influences aircraft landing safety. A wet runway significantly increases the incidence rates of aircraft overrun. To study the influence of the skid-resistance performance of a runway on aircraft landing, a co-simulation method is proposed. First, a finite element (FE) model of the local tire-water film-runway simulation is established to obtain the combination coefficient-slip ratio curve of a tire on a wet runway. Second, a global model of an Airbus A320 virtual prototype (VP) is created. Then, on the basis of fuzzy control theory, a two-dimensional (2D) fuzzy controller of the aircraft AB is established. The friction coefficient-slip ratio curve of the tire on the wet runway obtained in the local simulation is introduced into the full-scale hydroplaning simulation model of the aircraft. Finally, the global-local multiscale simulation method is used to analyze the skid-resistance behaviour of the aircraft on three types of runways. It is found that the increase of water film thickness of the pavement and the increase of the grounding speed cause the attenuation of the friction coefficient of a runway, finally causing the reduction of the deceleration rate of the aircraft and the increase of the braking distance. [ABSTRACT FROM AUTHOR]

This article is related to the development of potholes in bituminous pavements possibly occurring in winter at negative temperature and in presence of pore water in the asphalt concrete (AC) layers. It was shown already that this type of degradation could be due to swelling of the AC pore water. A constitutive law was previously developed to model this phenomenon; the present article deals with its implementation in a finite element (FE) program to evaluate the mechanical effects induced by the propagation of a frost front in a pavement. This novel program handles the coupling between the thermoviscoelastic problem with swelling in AC materials and the heat equation with phase change. First applied to the modelling of characterization tests on partially saturated AC specimens, the developed program has proved to be relevant. Then, to get closer to onsite conditions, an original frost-thaw test was carried out on a bilayer AC structure partially saturated. The test led to the delamination of the two layers during the second frost-thaw cycle. Its modelling showed that the interface rupture was triggered by differential strains and self-stress fields developing in the sample. These results can provide an explanation to the initialisation of the pothole issue. [ABSTRACT FROM AUTHOR]

Three-dimensional numerical finite element (FE) biphasic models verified against the experimental data were developed aiming to study the accuracy of FE modelling in the prediction of viscoelastic properties of crumb rubber-modified asphalt binders. In the numerical models, crumb rubber-modified asphalt binders are considered as a heterogeneous composite material consisting of the original asphalt binder and rubber particles which respectively have viscoelastic and hyperelastic behaviours. Three different dosages of crumb rubber including 10, 15 and 20 wt% of the original asphalt are added. To capture rubber particles distribution within the bituminous matrix, a random generation method by using the MOA software (French acronym for random object modeller) was implemented based on rubber's minimum and maximum particle sizes. In order to determine the viscoelastic properties of the original asphalt binder as well as the crumb rubber-modified ones, the dynamic shear rheometer (DSR) was used. The excellent agreement between the numerical FE modelling and experimental results witnessed the capability of biphasic finite element models to predict the visco-hyperelastic behaviour of crumb rubber-modified asphalt binders having an error lower than 9%. [ABSTRACT FROM AUTHOR]

The fatigue properties of the asphalt pavement layer are influenced significantly by different strain levels and temperatures. This research investigated the critical fatigue position within the asphalt pavement layer considering the couple effects of strain levels and temperatures. Firstly, field tests were conducted to measure the typical temperature distribution of the asphalt pavement layer. Secondly, laboratory four-point beam fatigue test and dynamic modulus test were applied to evaluate the fatigue life and the dynamic modulus of the asphalt mixture, respectively. Based on the results of field and laboratory tests, the distributions of strain and fatigue damage within the asphalt layer at different temperature conditions were calculated. It was found that the fatigue life of asphalt mixture decreased with the rising strain level but increased with the rising temperature. The critical fatigue position in the flexible pavement changed from 5 to 20 cm when the pavement temperature condition varied from high to medium/low. In terms of the semi-rigid pavement, this position varied between 6 and 12 cm at different temperature conditions. In addition, the fatigue damage within the semi-rigid pavement at high temperature was found to be as noticeable as that at medium/low temperatures. Thus, the fatigue properties of the asphalt layer at higher temperatures need to be carefully evaluated as well. [ABSTRACT FROM AUTHOR]