Pavement Thickness Research Articles

Longitudinal Cracking in Alternate Jointed Plain Concrete Panel Widths in Wisconsin

This paper presents the results of comparative analyses of longitudinal cracking occurring in wider concrete panels (>12ft) in Wisconsin. The analysis revealed that approximately 60% of 1,008 segments involved in the study experienced longitudinal cracking. For the same pavement thickness and joint spacing, panel widths of 12ft and 14ft that exhibited higher amounts of longitudinal cracking than the larger 15-ft panel, received corresponding higher levels of truck traffic than the 15-ft panel. Pavement segments with thickness of 9in at a joint spacing of 20ft experienced higher amounts of longitudinal cracking in 14ft and 15ft wide panels than in 12ft wide panels. For a 9-in pavement thickness at a joint spacing of 16ft, the best performance may be attained by using 12ft wide panels. For a 14-ft wide panel with 9-in or 10-in thickness, the best performance may be attained using a 15-ft joint spacing. In addition, models developed showed that longitudinal cracking variations in 10-in 14-ft wide panels at 16-ft or 20-ft joint spacing is dictated by the Annual Average Daily Traffic, while percent trucks is the foremost factor that explains variations in longitudinal cracking for 12-ft and 15-ft wide panels at specific joint spacing and thickness values.

Design and construction of a roundabout in fibremix concrete

Road pavement constructed with fibremix concrete allows longer distances between joints compared to unreinforced concrete pavements. Fibremix concrete has been used in parking areas near motorways, city roundabouts, road crossings, bicycle paths and regional roads with uncracked lengths up to 80 m. Without a dedicated design tool for fibremix concrete pavements, the maximum crack-free slab length was obtained by trial and error during several projects. In 2015, with the experience from the past years, the Province of Noord-Brabant, a regional government in the Netherlands, has constructed a roundabout in fibremix concrete on a crossing between two regional roads. This paper describes the design, special details and execution of this roundabout in fibremix concrete. Some technical details of the roundabout: T-crossing on the N625 near the city of Oss, the Netherlands One single-lane roundabout: pavement width: 5.25 m Diameter: 50 m Thickness of concrete pavement: 25 cm Fibremix concrete (2 types of steel fibres + 1 type of polypropylene fibre) Only 6 doweled joints Note: the roundabout was designed and constructed by the Den Ouden Group in the period May – June 2015.

Surface Stresses of Thick Concrete Pavement Slabs Due To Traffic Loads and Non-Linear Temperature Distributions.

In this study, possibility of top-down cracking in concrete pavement was investigated. The main cause of the crack is supposed to be tensile stress at the top of the concrete slab. 3DFEM simulations that took into account actual temperature distributions throughout slab depth were performed on concrete pavements for a heavy duty road and an international airport. Thermal stress analysis revealed that nonlinear negative temperature distribution produces relatively large tensile stress at the top of the slab, which cannot be precisely estimated by conventional thermal stress equations based on the linear temperature distribution. Areas where the bottom surface of concrete slab was separated from the surface of underlying layer were very small, because the underlying layer deformed similarly as the slabs deformed and reduced the gap area. The combined stresses were also calculated with the application of both wheel and thermal loads. The maximum top combined stress occurred at a position away from the wheel loads. The ratio of the top combined stress in negative temperature gradient to the bottom combined stress in positive temperature gradient is greater in the airport pavement than that in the road pavement. The installation of dowels in joints reduced the combined stress in the loaded slab.

Implementation of Precast Concrete for Rapid Renewal of Pavements

The rapid repair and rehabilitation of roadways with high traffic volumes is a critical need faced by all highway agencies. This need has been the catalyst for development of long-lasting precast concrete pavement (PCP) systems as alternatives to cast-in -place procedures. In the US, PCP has been shown to be a ready-to-use technology, and its effective implementation has served to reduce construction-related congestion, improve work-zone safety, and provide long-lasting pavement performance. Highway agencies in the US have recognized the potential for using PCP to achieve long-life performance for pavement rehabilitation while reducing the overall duration of lane closures on heavily trafficked roadways. PCP typically is used where high volumes of traffic limit work zones to off-peak times such as nighttime periods, and where longlife pavement performance is desired. The uses of PCP include, but are not limited to: replacement of intersections where rutting and shoving of existing asphalt requires frequent maintenance activity; reconstruction of ramps and mainline sections of heavily trafficked roadways; full-depth replacement of deteriorated joints; reconstruction of bridge underpasses where prestressed concrete can provide increased load-carrying capacity without increasing pavement thickness; overlays of existing concrete and asphalt pavements; inlays of existing asphalt pavements; and the replacement of bridge approaches. This paper provides a brief summary of the highway agencies that used PCP during the years 2000 through 2014; a summary of the uses of PCP planned and underway by highway agencies in response to a rollout of PCP technology by the 2nd Strategic Highway Research Program (SHRP2), and key reference documents published by the Federal Highway Administration (FHWA) and others to advance the use of PCP technology.

Evaluation of Technologies for Nondestructively Determining Concrete Pavement Thickness

The U.S. Army Engineer Research and Development Center (ERDC) was tasked by the U.S. Air Force (USAF) to evaluate the capability of emerging nondestructive testing equipment to accurately estimate the thickness of pavement surfaces without requiring large footprint equipment or pavement repairs. The ERDC research team conducted an evaluation of eleven nondestructive technologies, including eight ground penetrating radar devices and three different seismic technologies, on nineteen concrete test locations with varying pavement thicknesses. For each of the different pavement types, a single core was extracted to provide calibration points. The involved vendors and researchers estimated initial thickness, and upon receiving the calibration core thicknesses, final thickness estimates were computed. The accuracy of each technology was quantified by calculating the absolute difference between the actual core measurement and the estimated measurement. This paper describes the eleven different technologies, their performance on the test locations, and comparisons in terms of accuracy and implementation difficulty.

The high value utilization characteristics of coal gangue powder with emulsified asphalt mastic through rheological and viscoelastic damage theory

In order to solve the problems of rutting and early fatigue cracks in emulsified asphalt cold recycled pavement, and the shortage of natural stone resources and new environmental hazards caused by the use of traditional limestone powder filler. In this study, coal gangue powder was added to prepare Emulsified Asphalt Mastic (EAM) to improve the rheological properties and fatigue performance. A series of tests, including frequency scanning, temperature scanning, Multiple Stress Creep Recovery (MSCR), Linear Amplitude Scanning (LAS), and Fourier Transform Infrared spectroscopy (FTIR) were conducted. Through rheology theory, viscoelastic damage theory, the impact of three fillers: Coal Gangue Powder (CGP), Limestone Powder (LP) and Portland Cement (PC), as well as four kinds of Powder-Binder ratios (P/B) (0.6, 0.9, 1.2, 1.5) on the high temperature rheology and medium temperature fatigue performance of EAM was analyzed. The findings reveal that the filler content has a great influence on the proportion of viscoelastic components of EAM in the low frequency domain. The complex shear modulus (G*) and phase angle (δ) of EAM were suitable for Christensen-Anderson-Marasteanu model (CAM) model in the wide frequency domain. Increasing the filler content and Rotating Thin Film Oven Test (RTFOT) aging can improve the high-temperature stability and stress sensitivity of EAM, but it reduced its fatigue resistance. The high temperature performance of EAM containing PC and CGP exhibit superior high-temperature performance compared to LP fillers. Conversely, LP mastic demonstrate superior anti-fatigue performance under actual strain levels in both thin and thick asphalt pavement layers, surpassing the performance of PC mastic and CGP mastic. Therefore, coal gangue powder can be used as a new type of green filler to replace limestone powder. An appropriate amount of incorporation can improve the high temperature stability of the mortar and does not have a huge impact on the fatigue performance. The most suitable range of P/B is identified as 0.6–1.0 when utilizing LP as the filler, 1.2–1.5 when utilizing PC or CGP as the filler.

THE ROAD AND THE ENVIRONMENT, A MARRIAGE OF CONVENIENCE: THICK POROUS PAVEMENTS

In the paper "The Road and the Environment, a Marriage of Convenience: Thick Porous Pavements," authors Jean-Pierre Christory, Gilles Pipien, Bernard Soudieu, and Jean Chauchot address the evolving demands on urban road construction towards integrating environmental considerations. With urban areas expanding, there's a rising emphasis on roads not just as traffic conduits but as elements contributing to environmental management, including noise control, hydrological management, and pollution control. The research focuses on the development and application of porous concrete pavements, distinguished by their capacity to handle noise, water, and pollution more effectively than traditional materials. These pavements, characterized by their thickness (generally over 15 cm) and lack of post-compacting variation, have demonstrated significant advantages in environmental management without compromising on traditional road durability and reliability. Field trials in France have confirmed the effectiveness of these pavements in urban settings, showing promise in terms of noise reduction, water management, and overall environmental impact mitigation. The paper suggests that with ongoing advancements in technology and design, porous pavements can significantly contribute to more sustainable and environmentally friendly urban infrastructure development. (Abstract generated by AI tool ChatGPT 4)

EUROPEAN CONCRETE ROAD STANDARDS AND PRACTICES

The scientific article "European Concrete Road Standards and Practices" by Raymond Sharp provides a comprehensive overview of the current standards and practices in the construction of concrete roads across Europe, focusing on twelve countries: Austria, Belgium, Czechoslovakia, Denmark, France, Great Britain, Italy, the Netherlands, Spain, Sweden, Switzerland, and West Germany. The research synthesizes data from the Permanent International Association of Road Congresses (PIARC) and the European Cement Association, including detailed synoptic tables prepared for previous European symposia on concrete roads. This study delves into the various factors influencing pavement design, including traffic levels, sub-grade strength, and pavement materials, discussing the complexities of predicting future traffic and the insensitivity of pavement costs to small traffic variations. It examines the philosophical and economic decisions that guide pavement thickness and highlights the standardization in pavement design across different nations, emphasizing the small changes in design thickness due to the proven success and economic efficiency of existing systems. Furthermore, the paper explores the influence of non-technical factors such as governmental policies and competition between construction methods on pavement design. It also discusses the impact of local material availability and construction practices on the cost and quality of road construction. The research concludes that while concrete pavements generally perform well and offer long life spans, there are multiple viable approaches to pavement design influenced by local conditions and historical practices. It suggests that imposing a uniform design approach across different environments and traditions is impractical, advocating for flexible, context-specific solutions in pavement engineering. (Abstract generated by AI tool ChatGPT 4)

Improving pavement structure at signalized intersections to reduce gas emissions

Abstract Road defects often occur at signalised intersections, leading to reduced vehicle speeds and traffic congestion. Road damage has a direct impact on increasing fuel consumption and vehicle emissions. So a benchmark is needed to assess the condition of the pavement, one of which is the PCI (Pavement Condition Index) method. PCI is the level of pavement surface condition. If there is known damage, it is necessary to make efforts to improve the pavement structure. One of them is with the help of SPDM (Shell Pavement Design Method) software, which is software that functions to determine the performance of asphalt in the form of pavement thickness. The results showed road damage at a signalled intersection using the PCI method, so that recommendations for handling the damage can be found. From these recommendations, road structure improvements are carried out with overlays analysed using the SPDM application. The overlay thickness is obtained by subtracting the SPDM design thickness and the total design thickness of the flexible layer. The result is the overlay thickness on Tentara Pelajar Road 49 mm, West Diponegoro Road 75 mm, and East Diponegoro Road 74 mm. Improvements to the pavement structure at signalised intersections can reduce vehicle gas emissions.

A versatile deformation-oriented criterion for optimisation-based backcalculation of the pavement moduli and thickness

ABSTRACT Optimisation-based backcalculation problem in order to extract pavement moduli and thickness have been drastically developed nowadays. It not only serves a feasible cost-effective technique but also shapes a special class of non-destructive tests. The historical course of evolution in this field has caused the emergence of a variety of detector criteria. In this regard, the conventional deformation-based variation criterion (CVC), calculates the discrepancies between the deflection of the pavement surface and the deflection computed by the numerical simulation engine. Indeed, the CVC suffers from the lack of knowledge in relevance with the deformation pattern of the pavement surface. To tackle this dim spot, the present research work aims to propose a versatile criterion called ‘deformation-pattern-based variation criterion (PVC)’ to estimate both moduli and thickness of pavement using the IAS metaheuristic optimisation algorithm. Remarkably, the proposed criterion, PVC, not only efforts to find the deflection points of the pavement surface but also strives to adjust a consistent deformation with the variation pattern of the pavement surface. To investigate the efficiency and robustness of the proposed technique, it is implemented on a hypothetical three-layer pavement and a four-layer field pavement. The obtained results confirmed the outperforming of the PVC compared with the CVC in terms of the pavement modulus and thickness estimation.

Assessment of Concrete Pavement Performance on Istanbul's BRT Lines

The performance of concrete pavements is directly related to stresses and vertical displacements generated by vehicle loads. Selecting appropriate pavement and base thickness is crucial for extending service life in heavy vehicle areas like Istanbul's bus rapid transit lines.This study aims to calculate the maximum stress and vertical displacements caused by Istanbul's bus rapid transit vehicles on concrete pavements. There are currently four types of buses actively operating on Istanbul's bus rapid transit line, each with different axle configurations and load capacities. Stresses and vertical displacements were calculated for the heaviest axle configuration of these buses under edge and center loading conditions using the Finite Element Method (FEM). These analyses were repeated across three different overlay conditions: concrete overlay of asphalt, concrete overlay of concrete, and concrete overlay on granular base. A total of 24 analyses, covering various loading conditions and pavement configurations, were conducted using the EverFE software. This research reveals maximum stress and vertical displacement values under various loading conditions, base properties, and slab thicknesses, offering critical insights for determining pavement thickness and guiding maintenance strategies. This study also fills the gap in the literature regarding the determination of concrete pavement thickness for BRT lines.

Influence of the Bailey Gradation Method on the Mechanical Behavior of Asphalt Mixture Containing Steel Slag as an Alternative Aggregate

This study evaluates the feasibility of reusing steel slag aggregates in asphalt concrete, analyzing the impact of different gradation methods (Bailey method and conventional Brazilian method) on the mechanical properties of the mix. Using the Marshall methodology and Petroleum Asphalt Concrete (PAC) 30/45, parameters such as Marshall stability, indirect tensile strength, resilient modulus, fatigue life through diametral compression, and permanent deformation (Flow Number) were investigated. Additionally, a simulation for a hypothetical section in the city of Rio de Janeiro, Brazil, was performed using the mechanistic-empirical pavement design software, Medina. The results showed that the mixture produced by the Bailey method outperformed the others in all analyses. This method led to a more compact mix, providing significant advantages, including up to a 35% reduction in final pavement thickness and a 110.6% increase in Flow Number (FN), enabling the mix to withstand extremely heavy traffic, as reported in the literature. Regarding fatigue life, the Bailey mixture achieved a fatigue class of 4, compared to the conventional mixture class 1. These findings indicate that using the Bailey gradation method for producing asphalt mixtures with steel slag can optimize binder content and improve resistance to permanent deformation and fatigue, making it a viable and sustainable alternative for asphalt pavements.

Application of Ground Penetrating Radar in the Assessment of Aged Roads: Focus On Complex Structures Under Different Weather Conditions

Ground penetrating radar (GPR) has been widely used to assess asphalt and pavement, especially in quality testing for newly constructed roads. However, its usage has been limited in regard to aged roads. Thus, this study focuses on the applicability of GPR to extract diverse information regarding structure, thickness, and various conditions, including the moisture content of an aged road section that has undergone repeated renewals. First, two methods were employed to calculate the thickness and dielectric values; the reflection amplitude and ground truth methods. The analysis was done by RADAN 7 software. Based on the findings, the average error of thickness on the same day between continuous GPR and the core data were 2.87% and 8.72%, respectively. Second, dielectric analysis of three structural units was performed under different moisture conditions. As a result, the average dielectric values of macadam (3, 3.3, and 4), surface asphalt layer (4, 7.06, and 8.31), and cement-treated base (4.83, 10.88, and 11.88) were determined under dry, medium-wet, and wet conditions, respectively. The volumetric water difference (f) within the pavement was also estimated. As for the asphalt, macadam, and cement-treated base, the difference in the volume fraction of water (f) was 0.06, 0.01, and 0.1, respectively, under dry and wet conditions, and 0.04, 0.004, and 0.09, respectively, under dry and medium-wet conditions. Overall, the findings demonstrate that reasonably accurate assessments of the pavement thickness, structure, dielectric values, and amplitude of aged roads can be achieved by using a GPR survey under various conditions.

Comparison of Rigid Pavement Planning Using PD T-14-2003 and NAASRA 1987 Methods in Industrial Areas

As vital infrastructure, roads are a means of transportation access and function as a distribution route for goods and services. Road pavement plays a crucial role in highway construction, necessitating proper planning according to Indonesian standards and planning criteria to ensure smooth land transportation and provide comfort and safety for its users. This study aims to provide information on road conditions, drainage dimensions, and construction costs. Planning is crucial in every road construction design, particularly for rigid pavement, based on survey data collected from the road section. Numerous methods exist for calculating the design value of rigid pavement. We use the Pd T-14-2003 method and the NAASRA 1987 method (National Association of Australian State Road Authorities) to plan rigid pavement thickness in the industrial area of PT. Bukit Muria Jaya Kudus. The Pd T-14-2003 method yielded a JSKN of 4x107 and a CBR of 35% for the subgrade, resulting in a plate thickness of 150 mm. While the Naasra 1987 planning method achieved a JSKN of 6x107 and a CBR of 35% for the base soil, a plate thickness of 160 mm was obtained with a value of K = 80 kPa/mm. The reinforcement planning using the Pd T-14-2003 and Naasra 1987 methods involves longitudinal reinforcement D10 mm at a distance of 150 mm and transverse reinforcement D10 mm at 250 mm. The drainage dimensions at the cross-section location are width x height (1 m x 1 m), and the guard's height is 0.2 m.

Subgrade performance assessment for rigid runway using long-term pavement performance database

Maintaining desired subgrade performance is an effective way to reduce runway pavement deterioration. Due to lack of extensive field test data, life-cycle performance of runway subgrade has not been fully understood. In order to quantitatively estimate subgrade condition, a novel method of evaluating subgrade performance was developed and validated using the 726 sets of Heavy Weight Deflectometer (HWD) test data of ten runway sections. Statistical analysis demonstrates that the structural behaviour of rigid runway subgrade follows normal distribution in different service stages and can be efficiently evaluated by the subgrade performance index (ψ). The results of factor analysis show that Accumulated Air Traffic Volume (ATV) during service life is the major cause of spatial variations in subgrade condition. In the designed service period of runway, it validates that sea-reclaimed subgrade results in faster degradation in the initial stage of service life while thicker pavement exhibits better capability in protecting the subgrade soil in long-term view. Besides, the differences in applied loads and pavement thickness give rise to the subgrade performance variation in longitudinal direction. Meanwhile, the comparison between the main and the less trafficked test lines in transversal direction reveals that the aircraft impacts play a positive role in resisting the natural fatigue process. By the suggested method, subgrade performance of HWD test points can be categorized into 4 levels from “Excellent”, “Good”, “Fair” to “Poor” based on ψ value. It is helpful for airport agency to make scientific decisions on Maintenance and Rehabilitation (M&R) treatment by calculating the effective area of envelope (β) using the ratio of subgrade performance (η).

Optimization of Pavement Structure Using High-Modulus Asphalt Coating Considering the Effects of Base-Course Combinations

High-modulus asphalt concrete (HMAC) has been widely used in the surface coating of high-grade pavement. Due to HMAC’s modulus being significantly higher than traditional asphalt concrete, the mechanical responses of a pavement structure using an HMAC coating must be notably different from those of a traditional asphalt pavement structure. Moreover, when asphalt surface coating is fixed, the selection of base-course combinations will determine the mechanical response of the whole pavement structure. However, previous studies usually analyzed the mechanical response of pavement structures at limited combinations of base-courses, resulting in difficulties comprehensively understanding the laws of mechanics and effectively optimizing the HMAC pavement structure. Hence, in this study, a total of 108 groups of numerical experiments under six working conditions of base-course combinations are carried out using orthogonal experimental design to investigate the mechanical response of pavement structures using HMAC coatings using the PR MODULE high-modulus additive. The effects of pavement thickness, material modulus, and structural combination on mechanical responses are analyzed for the 108 groups to determine the optimal pavement combinations based on the balance of mechanical response and economic efficiency. The results show the following: The effect of the base layer type on mechanical response is more significant than that of the subbase layer type. Surface and undersurface layer thickness for the granular material base layer; surface and base layer thickness for the asphalt mixture base layer; and base layer thickness, subbase layer modulus, and base layer modulus for the inorganic binder mixture base layer are the key factors for mechanical response. Finally, six recommended HMAC pavement structure configurations for various base-courses are proposed.

Development and verification of rutting prediction model based on variable frequency load test

ABSTRACT An innovative rutting test method was developed based on the existing rutting prediction model to improve the rutting prediction model used in the asphalt pavements. The loading mould was improved based on test requirements and equipment characteristics, and small-scale and full-scale variable frequency load rutting tests were conducted. Nonlinear multiple regression analysis was conducted on the test results using numerical analysis software, converting driving speed into loading frequency and incorporating it into the rutting prediction model. This resulted in a permanent deformation prediction model for asphalt mixtures, incorporating factors such as temperature, pressure, loading cycles, loading frequency, and pavement thickness. Fourteen highways were selected as validation sections. The validation results showed that the average error of the prediction model established in this study was 15.48%, compared to 24.42% and 27.94% for the other two models. For different grades of highways, the load frequency parameter can distinguish the rutting conditions under different driving speeds, making the rutting prediction model established in this study more accurate compared to measured values.

A Comparative Study of Pavement Roughness Prediction Models under Different Climatic Conditions

Predicting the International Roughness Index (IRI) is crucial for maintaining road quality and ensuring the safety and comfort of road users. Accurate IRI predictions help in the timely identification of road sections that require maintenance, thus preventing further deterioration and reducing overall maintenance costs. This study aims to develop robust predictive models for the IRI using advanced machine learning techniques across different climatic conditions. Data were sourced from the Ministry of Energy and Infrastructure in the UAE for localized conditions coupled with the Long-Term Pavement Performance (LTPP) database for comparison and validation purposes. This study evaluates several machine learning models, including regression trees, support vector machines (SVMs), ensemble trees, Gaussian process regression (GPR), artificial neural networks (ANNs), and kernel-based methods. Among the models tested, GPR, particularly with rational quadratic specifications, consistently demonstrated superior performance with the lowest Root Mean Square Error (RMSE) and highest R-squared values across all datasets. Sensitivity analysis identified age, total pavement thickness, precipitation, temperature, and Annual Average Daily Truck Traffic (AADTT) as key factors influencing the IRI. The results indicate that pavement age and higher traffic loads significantly increase roughness, while thicker pavements contribute to smoother surfaces. Climatic factors such as temperature and precipitation showed varying impacts depending on the regional conditions. The developed models provide a powerful tool for predicting pavement roughness, enabling more accurate maintenance planning and resource allocation. The findings highlight the necessity of tailoring pavement management practices to specific environmental and traffic conditions to enhance road quality and longevity. This research offers a comprehensive framework for understanding and predicting pavement performance, with implications for infrastructure management both locally and worldwide.

Statistical and machine learning models for predicting spalling in CRCP

Continuously reinforced concrete pavement (CRCP), crucial for the resilience of transportation infrastructure owing to its continuous steel reinforcement, confronts a critical challenge in the form of spalling—a distress phenomenon posing a threat to pavement durability and overall structural integrity. The detachment or breakage of concrete from the surface compromises CRCP’s functionality and raises safety concerns and escalating maintenance costs. To address this pressing issue, our study investigates the multifaceted factors influencing spalling, employing a comprehensive approach that integrates statistical and machine learning techniques for predictive modeling. Descriptive statistics meticulously profile the dataset, emphasizing age, thickness, precipitation, temperature, and traffic parameters. Regression analysis unveils key relationships, emphasizing the significance of age, annual temperature, annual precipitation, maximum humidity, and the initial International Roughness Index (IRI) as influential factors. The correlation matrix heatmap guides feature selection, elucidating intricate interdependencies. Simultaneously, feature importance analysis identifies age, Average Annual Daily Traffic (AADT), and total pavement thickness as crucial contributors to spalling. In machine learning, adopting models, including Gaussian Process Regression and ensemble tree models, is grounded in their diverse capabilities and suitability for the complex task at hand. Their varying predictive accuracies underscore the importance of judicious model selection. This research advances pavement engineering practices by offering nuanced insights into factors influencing spalling in CRCP, refining our understanding of spalling influences. Consequently, the study not only opens avenues for developing improved predictive methodologies but also enhances the durability of CRCP infrastructure, addressing broader implications for informed decision-making in transportation infrastructure management. The selection of Gaussian Process Regression and ensemble tree models stems from their adaptability to capture intricate relationships within the dataset, and their comparative performance provides valuable insights into the diverse predictive capabilities of these models in the context of CRCP spalling.

Field measurement and numerical simulation on vertical temperature gradient of steel box girders

The vertical temperature gradient (VTG) is a critical factor contributing to thermal stresses or deformations in bridge structures. However, the current provisions concerning the VTG of steel box girders are inadequate. Accordingly, this paper systematically investigated the VTG of a steel box girder in Wuhan using field measurement and numerical simulations. The temperature distributions of the steel box girder were first characterised based on measured temperature data. A thermal model of the steel box girder was then established using measured time-varying meteorological data, with the convective heat transfer coefficient obtained through an inversion method to update the model. The numerical findings align well with the observed temperature, and the fitted unfavourable VTG values exceed the current normative threshold. Furthermore, parametric investigations were carried out to reveal the impacts of meteorological and structural parameters on the VTG. The results indicate that solar radiation and pavement thickness have a considerable impact on the VTG. Finally, this research recommends that the present VTG guidelines should be modified by introducing appropriate adjustment factors related to the level of solar radiation intensity in different regions to strengthen their capacity for safeguarding.