Dissertations / Theses on the topic 'Axle Loads'

Several aspects of vehicle-pavement interaction have been studied and discussed in this thesis. Initially the pavement response is studied through a quasi-static and a dynamic computationally efficient framework under moving traffic loads. Subsequently, a non-stationary stochastic solution has been developed in order to account for the effect of pavement surface deterioration on pavement service life.The quasi-static procedure is based on a superposition principle and is computationally favourable, as it requires only a reduced incremental problem to be solved numerically. Using the developed framework, the effect of vehicle configuration and traffic characteristics on the damage induced in pavements is investigated numerically. It is shown that the developed numerical model provides a more accurate explanation of different distress modes.In the dynamic approach the pavement roughness and vehicle suspension system are linked to a dynamic pavement model in order to account for the dynamic effects of vehicle-pavement interaction on pavement response. A finite element method is employed in order to establish the response function for a linear viscoelastic pavement structure with dynamic effects taken into account. The developed computational procedure is applied to evaluate the effect of the pavement surface roughness on the pavement structure response to truck traffic loadings.Furthermore, the deterioration trends for the flexible pavement surface have been investigated based on field measurements of longitudinal profiles in Sweden. A predictive function is proposed for surface deterioration that is based on the average gradient of yearly measurements of the road surface profiles in Swedish road network. The developed dynamic framework is further elaborated to a non-stationary stochastic approach. The response of the flexible pavement is given for a non-stationary random case as the pavement surface deteriorates in pavement service life, thus influencing the magnitude of the dynamic loads induced by the vehicles. The effect of pavement surface evolution on the stress state induced in the pavement by moving traffic is examined numerically. Finally the effect of surface deterioration on pavement service life has been investigated and discussed in the thesis by incorporating the proposed prognostic surface deterioration model into a ME design framework. The results are discussed for different case studies with different traffic regimes. It was indicated that the predicted pavement service life decreases considerably when the extra dynamic loads, as a result of pavement surface deterioration, has been taken into account. Furthermore, the effect of performing a predictive rehabilitation process (i.e. resurfacing) has been studied by employing a LCC framework. The application of preventive maintenance was shown to be effective, especially when the deterioration rate is high.<br><p>QC 20141119</p>

The need for modern transportation systems together with the high demand for sustainable pavements under applied loads have led to a great deal of research on concrete pavements worldwide. Development of finite element techniques enabled researchers to analyse the concrete pavement under a combination of axle group loadings and environmental effects. Consequently, mechanistic approaches for designing of concrete pavements were developed based on results of finite element analyses. However, unpredictable failure modes of concrete pavements associated with expensive maintenance and rehabilitation costs have led to the use of empiricalmechanistic approach in concrete pavement design. Despite progressive knowledge of concrete pavement behaviour under applied loads, concrete pavements still suffer from deterioration due to crack initiation and propagation, indicating the need for further research. Cracks can be related to fatigue of the concrete and/or erosion of materials in sub-layers. Although longitudinal, midedge and corner cracks are the most common damage modes in concrete pavements, Austroads method for concrete pavement design was developed based on traditional mid-edge bottom-up transverse cracking introduced by Packard and Tayabji (1985). Research presented in this thesis aims to address the most common fatigue related distresses in concrete pavements. It uses comprehensive finite element models and analyses to determine the structural behaviour of concrete pavements under vehicular loads and environmental effects. Results of this research are supported by laboratory tests and an experimental field test. Results of this research indicate that the induced tensile stresses within the concrete pavement are significantly affected by vehicle speed, differential temperature gradient and loss of moisture content. Subsequently, the interaction between the above mentioned factors and concrete damage modes are discussed. Typical dynamic amplifications of different axle groups are presented. A new fatigue test setup is also developed to take into consideration effects of pavement curvature on fatigue life of the concrete. Ultimately, results of the research presented in this thesis are employed to develop a new guide for designing concrete pavements with zero maintenance of fatigue damage.

The field of monitoring is one of rapid development. Advances in sensor technologies, in data communication paradigms and data processing algorithms all influence the possibilities of Structural Health Monitoring, damage detection, traffic monitoring and other implementations of monitoring systems. Bridges are a very critical part of a country’s infrastructure, they are expensive to build and maintain, and many uncertainties surround important factors determining the serviceability and deterioration of bridges. As such, bridges are good candidates for monitoring. Monitoring can extend the service life and avoid or postpone replacement, repair or strengthening work. Many bridges constitute a bottleneck in the transport network they serve with few or no alternative routes. The amount of resources saved, both to the owner and the users, by reducing the amount of non-operational time can easily justify the extra investment in monitoring. This thesis consists of an extended summary and three appended papers. The thesis presents advances in sensor technology, damage identification algorithms and Bridge Weigh-In-Motion techniques. Two case studies are carried out. In the first a bridge and traffic monitoring system is implemented in a highway suspension bridge to study the cause of unexpected wear in the bridge bearings. In the second a fully operational Bridge Weigh-In-Motion system is developed and deployed in a steel railway bridge. The gathered data was studied to obtain a characterization of the site specific traffic.<br>QC 20111122

The field of bridge monitoring is one of rapid development. Advances in sensor technologies, in data communication and processing algorithms all affect the possibilities of Structural Monitoring in Bridges. Bridges are a very critical part of a country’s infrastructure, they are expensive to build and maintain, and many uncertainties surround important factors determining their serviceability and deterioration state. As such, bridges are good candidates for monitoring. Monitoring can extend the service life and avoid or postpone replacement, repair or strengthening works. The amount of resources saved, both to the owner and the users, by reducing the amount of non-operational time can easily justify the extra investment in monitoring. This thesis consists of an extended summary and five appended papers. The thesis presents advances in sensor technology, damage identification algorithms, Bridge Weigh-In-Motion systems, and other techniques used in bridge monitoring. Four case studies are presented. In the first paper, a fully operational Bridge Weigh-In-Motion system is developed and deployed in a steel railway bridge. The gathered data was studied to obtain a characterization of the site specific traffic. In the second paper, the seasonal variability of a ballasted railway bridge is studied and characterized in its natural variability. In the third, the non-linear characteristic of a ballasted railway bridge is studied and described stochastically. In the fourth, a novel damage detection algorithm based in Bridge Weigh-In-Motion data and machine learning algorithms is presented and tested on a numerical experiment. In the fifth, a bridge and traffic monitoring system is implemented in a suspension bridge to study the cause of unexpected wear in the bridge bearings. Some of the major scientific contributions of this work are: 1) the development of a B-WIM for railway traffic capable of estimating the load on individual axles; 2) the characterization of in-situ measured railway traffic in Stockholm, with axle weights and train configuration; 3) the quantification of a hitherto unreported environmental behaviour in ballasted bridges and possible mechanisms for its explanation (this behaviour was shown to be of great importance for monitoring of bridges located in colder climate) 4) the statistical quantification of the nonlinearities of a railway bridge and its yearly variations and 5) the integration of B-WIM data into damage detection techniques.<br><p>QC 20140910</p>

Vehicle over loading, or single axle over loading, is one of the major causes of pavement deterioration. Trafik Verket (TV), the Swedish Transport Administration, recognized that the current process for estimating traffic volume should be reevaluated, and if possible improved. This degree project uses data from the Bridge Weigh in Motion (BWIM) system to study the actual loads applied to Swedish highways. The axle load spectrum is plotted with the conventional frequency distribution plots, and with a new cumulative distribution approach. The paper introduces the maximum allowable potential vehicle weight MAPVW concept, and uses this visual technique to identify overloads for different vehicle geometries. The paper concludes that for 5 and 6 axle trucks the triple axle is frequently overloaded, while for longer trucks one of the dual axles is often over loaded. The highest over loads tend to be on the driving axle, suggesting incorrect loading procedures.

Thesis (PhD)--Stellenbosch University, 2012.<br>ENGLISH ABSTRACT: Road Tra c legislation prescribes constraints on the forces/loads which vehicles may exert on the road at contact surfaces or load points. These constraints have bearing on speci c contact surfaces or groups of contact surfaces. The constraints are in the form of maximum force values and maximum ratios, which may exist between forces. The forces exerted by a vehicle on the road is determined by a combination of the vehicle's own mass, dimensional characteristics, and the mass and position of its cargo. The mass and position of the cargo can be modelled by only considering its centroid. The centroid's position is linked to a certain cargo arrangement. It is necessary, in terms of legal constraints, to distinguish between legally permissable- and non-permissable arrangements. Methods are proposed in this dissertation to determine the borders for the position of the centroid according to cargo-mass, for a variety of vehicle con gurations. The determination of borders for the position of the centroid is the result of a three part process. Firstly, the legal limits are translated to mathematical inequalities that must be satis ed for the forces at contact surfaces. Secondly, conservative parametric estimates for the forces, in terms of the position and the mass of the centroid of a given vehicle, must be derived. Finally these estimates are incorporated into the load constraints and an enclosed permissable area for the centroid is found. These position constraints are suitable inputs to solution methods of various cargo arrangement problems. Linear programmes which can solve certain general arrangement problems by utilising the position constraints on the centroid, were successfully developed. Solutions are presented for the arrangement of pallet-freight, as well as the arrangement of cargo units with asymetrical centroids over the length or width of a vehicle's cargo area.<br>AFRIKAANSE OPSOMMING: Padvervoerwetgewing skryf grense op kragte/laste voor wat voertuie by kontakoppervlakke of laspunte, op die pad mag uitoefen. Hierdie voorskrifte het betrekking op spesi eke laspunte en groepe van laspunte. Die voorskrifte is in die vorm van maksimum laswaardes by laspunte en maksimum ratio's wat tussen sekere laste mag bestaan. Die laste wat 'n voertuig op die pad uitvoer word bepaal deur 'n kombinasie van die voertuig se eie massa, dimensionele eienskappe, sowel as sy vrag se massa en posisie. Die vrag se massa en posisie kan gemodelleer word deur slegs die massamiddelpunt daarvan te beskou. Die massamiddelpunt se posisie word gekoppel aan 'n bepaalde vragrangskikking. Dit is nodig om, in terme van wetlike voorskrifte, te kan onderskei tussen wetlik toelaatbare en -ontoelaatbare rangskikkings. Metodes word in hierdie proefskrif voorgestel waarmee daar grense vir die posisie van die vragmassamiddelpunt bepaal kan word na gelang van die vragmassa, vir 'n verskeidenheid van voertuigkon gurasies. Die bepaling van grense vir die posisie van die vragmassamiddelpunt is die resultaat van 'n drieledige proses. Eerstens word die wetlike beperkings herlei na wiskundige ongelykhede waarbinne laste by kontakoppervlakke moet val. Tweedens word konserwatiewe parametriese beramings vir die laste verkry in terme van die ligging en massa van die vragmassamiddelpunt vir 'n gegewe voertuig. Laastens word hierdie beramings in die lasbeperkings opgeneem om 'n afgebakende toelaatbare gebied vir die vragmassamiddelpunt se posisie te verkry. Hierdie posisiebeperkings is geskik om as inset te dien in die oplossingmetodes van 'n verskeidenheid van vragrangskikkingsprobleme. Line^ere programme wat sekere algemene rangskikkingsprobleme kan oplos deur die aanwending van posisiebeperkings op die vragmassamiddelpunt, is suksesvol ontwikkel. Oplossings word aangebied vir die rangskikking van paletvrag, asook die rangskikking van vrageenhede met asimmetriese massamiddelpunte oor die lengte of breedte van 'n voertuig se vragarea.

Volvo Construction Equipment is highly regarded for robust products, but with an increasing competition in their market, development of the product portfolio is more important than ever. One step being carried out is to reduce losses in powertrains and increase the fuel efficiency for solutions such as articulated haulers and wheel loaders. This would eventually lower the fuel costs and emissions for the end customer. With this development, Volvo CE could strengthen their position in the market while also contributing to reducing the construction industry's environmental impact. By investigating the front bogie axle of the recently introduced hauler, Volvo A60H, important information about possible reductions and the distribution of the current losses were found. The investigation focused on a front bogie axle, but some of the results are applicable for other applications such as wheel loaders as well, since a lot of the technology in the axles are similar. A conceptual study was performed where completely new ideas were generated, such as implementing a dry sump system in the axle, as well as ideas for improving the subcomponents currently found in the axle. Two cases were presented for the evaluation of concepts, one with a fully loaded dump body and low speeds, and one with an unloaded dump body and a wider speed interval. The concepts were later evaluated using calculation tools such as MATLAB and a Simulink-model was created for the losses in the axle. When combining concepts that reduces load dependent losses, a potential reduction of 64% of the axle's total losses was achieved for the case with a full dump body. The largest improvement found for the load independent losses was 8% with an unloaded hauler and the highest speed investigated, 50 km/h. A dry sump system improves the axle's efficiency with 45% in optimal working conditions, but was found to lower the efficiency at other conditions. Room for improvement of axle losses currently exists both for load dependent and load independent losses. The evaluation performed pointed towards the load dependent losses being the largest influence on the total losses, even with an unloaded dump body and high speeds. This is an interesting observation since a lot of work at Volvo CE has revolved around reducing the load independent losses since these are easier to affect with different lubrication levels and rotational speeds. A test methodology for load dependent losses should be implemented in order to validate the results of this thesis work, and also to aid further development at Volvo CE.

Soil structure and crop response under annual compactive loads of 10 and 18 t/axle and compaction alleviation treatments were assessed in a continuous corn production system. The alleviation treatments consisted of chemical conditioning with a non-ionic surfactant, and subsoiling with narrow-tined and winged implements. Parameters utilized for determining effects on soil structure were bulk density, water retention characteristics and soil profile characteristics. Significant topsoil and subsoil compaction resulted from both loading levels. Crop yield reductions due to compactive loading ranged from 18 to 27% under optimal weather conditions and were as high as 55 to 86% under adverse weather conditions. Soil amendments by chemical conditioning had no beneficial effect on soil structure or crop yields. Inter-row subsoiling with narrow-tined and winged subsoilers was effective in reducing soil compaction and increasing crop yields.<br>Soil bulk density measurements gave good indication of overall compaction to a depth of 0.4 m and correlated well with crop yields, but were unable to locate differences between compactive treatments. Water retention characteristics indicated significant differences between compactive treatments to a depth of 0.6 m. Soil profile characteristics were useful for determining ped type and size as well as rooting depth and gave the best overall assessment of compaction alleviation effects.<br>Studies were also conducted to develop a method for predicting soil compactibility that would serve to manage soil compaction at the farm level. Preliminary studies focused on the determination of soil material properties for predicting bulk density changes under applied loads. Further investigations were conducted on the variations in constrained modulus, cone index and soil bulk density values under uniaxial loading. A model relating constrained modulus as a function of cone index, bulk density and soil moisture content was developed. Subsequent studies conducted yielded significant relationships between penetration resistance and soil compactibility as indicated by constrained modulus and coefficient of compressibility. Relationships obtained between penetration resistance and parameters of compactive work and bulk density change indicated the feasibility of assessing soil compactibility at the farm level.

In this thesis the effect of axle load spreading through ballast and the effect of support stiffness has been investigated on short span railway bridges. Two types of bridges, simply supported bridges and bridges with integrated backwalls, have been modeled with 2D beam elements. When analyzing the load spreading effect, two types of load shapes have been considered. The first one is the load shape proposed in Eurocode where the axle load is modeled with three point loads where 50% of the axle load acts on the sleeper located underneath the wheel and 25% on the two adjacent sleepers, respectively. Therefrom the loads are further distributed through the sleepers and the ballast. The second load shape that has been studied is a triangular load shape. These two load shapes have been modeled both with different numbers of point loads and as distributed line loads to see how the dynamic response of the bridges is affected and thereby find what level of accuracy that is required to capture the full effect of the load spreading. For the bridges with integrated backwalls the supports were also modeled as springs with varying stiffness to see how the dynamic response was affected. The response was measured in terms of vertical acceleration and bending moment. From the simulations the conclusion can be drawn that the triangular load shape gives significantly lower bridge responses than the Eurocode load shape. It is further found that modeling the axle loads with point loads can give spurious acceleration peaks, which in the case of bridges with integrated backwalls often are critical. For these bridges it is necessary to enhance the accuracy of the load spread, either by increasing the number of point loads or using a distributed line load. From the spring support simulations, it can be seen that support stiffness has great influence on the dynamic response of bridges with integrated backwalls. For certain values the response is increased, whereas for other values a large reduction is obtained.

An indirect tire pressure monitoring system uses the wheel rolling radius as an indicator of low tire pressure. When extra load is put in the trunk of a car, the load distribution in the car will change. This will affect the rolling radius which in its turn will be confused with a change in the tire pressure. To avoid this phenomenon, the load distribution has to be estimated. In this thesis methods for estimating the pitch angle of a car and an offset in the pitch angle caused by changed load distribution are presented and when an estimate is derived, a load distribution can be derived. Alot of available signals are used but the most important are the longitudinal accelerometer signal and the acceleration at the wheels derived from the velocity of the car. A few ways to detect or compensate for a non-zero road grade are also presented. Based on the estimated offset, a difference between the front and rear axle heights in the vehicle can be estimated and compensating for the changed load distribution in an indirect tire pressure monitoring system will be possible.

This thesis is a product of the U.S. Army Corp of Engineer's desire to develop a more accurate procedure for estimating the load capacity of an in-service T-beam bridge. A bridge type that is a stumbling block for U.S. Army field engineers due to the unknown amount and placement of the flexural reinforcement in the T-beam girder cross-sections. Personnel from the U.S. Army Corp of Engineer's Waterways Experiment Station in cooperation with personnel from Virginia Tech conceived a procedure that is potentially more accurate, can be quickly executed in the field, and is relatively easy to use by field engineers. In general, the procedure provides a method for transition between the quantity of flexural reinforcement in a reinforced concrete T-beam and the member's actual moment of inertia. Specifically, the goal of this thesis is to evaluate the accuracy of selected, effective moment of inertia models as a component in the proposed analysis procedure. The accuracy of the selected models is evaluated with test data generated from a testing program detailed herein, which load tested full-scale reinforced concrete T-beams. The test specimens were subjected to a closely-spaced, tandem-axle load configuration, a load configuration typical of military equipment.<br>Master of Science

A caracterização das cargas do tráfego é de grande importância para o dimensionamento de pavimentos, bem como para a quantificação do desempenho para fins de gerência de pavimentos. A utilização de abordagens empíricas para determinar os efeitos das cargas do tráfego nas estruturas de pavimentos, datadas dos anos 1960, apresentam sérias limitações, pois seus resultados são válidos somente para os mesmos, ou muito similares, fatores intervenientes que prevaleciam quando do seu desenvolvimento. Os fatores relativos às solicitações do tráfego e às características dos veículos (tipo de eixo, tipo de rodagem, pressão de enchimento dos pneus e tipo de suspensão) são bem diferentes, atualmente, daquelas existentes há 50 anos. Tendo em vista que os modelos de desempenho são importantes ferramentas dos sistemas de gerência de pavimentos (SGP) para prever a evolução da condição ao longo do tempo e/ou tráfego acumulado e, portanto, dependentes de uma consistente caracterização do tráfego, o objetivo desta pesquisa foi analisar os efeitos da caracterização do tráfego sobre o desempenho dos pavimentos, a partir da geração de modelos estatísticos baseados no conceito proposto pelo método da AASHTO 2002, de espectros de carga por eixo dos veículos comerciais de carga, comparando-os com o conceito de equivalência de carga, desenvolvido a partir do AASHO Road Test na década de 1950. Dados de pesagens realizadas no ano de 2008 no Posto de Pesagem de Veículos da SP-160 Rodovia dos Imigrantes, km 28, pista Sul, foram utilizados para o desenvolvimento dos espectros de carga e posterior modelagem. Testes estatísticos e práticos foram realizados para determinar a variabilidade mensal dos Fatores de Veículos (FV) em relação ao valor médio do ano de 2008. Apesar da análise estatística com a aplicação do teste Kolmogorov-Smirnov (K-S) ter apresentado diferenças significativas entre os espectros mensais e anuais, a variação observada nos fatores de tráfego não resultou em diferenças práticas na espessura final do pavimento. Os modelos estatísticos foram desenvolvidos separadamente para cada classe de veículo e de eixos que o compunha, tendo sido usadas distribuições de probabilidade Log-normal e Weibull para modelar os espectros de carga. Os parâmetros dos modelos foram obtidos através do método dos mínimos quadrados, complementado com a realização de testes K-S e Qui-quadrado, destacando-se a obtenção de coeficientes de determinação (R2) superiores a 0,90. A comparação entre os resultados previstos pelos modelos e os dados originais, feita tanto pela abordagem empírica como empírico-mecanística, com uso dos programas computacionais ELSYM5 e MEPDG, evidencia o modelo Weibull como o mais indicado para aplicação em rodovias brasileiras com características de tráfego semelhantes às da Rodovia dos Imigrantes.<br>The characterization of traffic loads is of great importance for pavement design, as well as for the measurement of performance in a pavement management system. The use of empirical approaches to determine the effects of traffic load on pavement structures, dating from the 1960\'s, presents serious limitations, since its results are just valid for the same or very similar intervening factors that prevailed at the time of its development. The traffic load factors and vehicle characteristics (axle type, tire type, tire inflation pressure, and suspension type) are quite different today from those existing 50 years ago. Given that the performance models are important tools of pavement management systems (PMS) to predict the evolution of pavement condition over time and/or accumulated traffic and therefore dependent on a consistent characterization of the traffic, the objective of this research was to analyze the effects of traffic characteristics on pavement performance through the generation of statistical models based on the concept proposed by the AASHTO 2002 method, axle load spectra of commercial vehicles, comparing them with the concept of load equivalence factor, developed through the AASHO Road Test in the 1950s. Data collected in 2008 in a weighing station located on Immigrant Highway - SP-160, km 28, southern runway, were used for the development of load spectra and subsequent modeling. Practical and statistical tests were performed to determine the variability of monthly vehicle-factors (FV) to the mean value for the year 2008. Despite the statistical analysis, performed by applying the Kolmogorov-Smirnov (KS) test, have shown significant differences between the monthly and annual spectra variation, there were not practical differences in the final thickness of the pavement associated to changes in vehicle-factors. Statistical models were developed for each vehicle class and for its axles, having been used Log-normal and Weibull probability distributions to model the load spectra. The model parameters were obtained from the method of least squares, complemented by the KS and chi-square tests, being important to mention that the coefficients of determination (R2) were greater than 0.90. The comparison between the results predicted by the models and the original data, made either by empirical and empiricalmechanistic approaches, with use of computer programs ELSYM5 and MEPDG, shows that the Weibull model is the most suitable for application in Brazilian highways with similar traffic characteristics to the Immigrants Highway.

This research evaluates four options to produce quality axle load data for pavement design: piezoelectric WIM sites (corrected and uncorrected data), static weigh scales, and a piezo-quartz WIM site. The evaluation applies four data quality principles: data validity, spatial coverage, temporal coverage, and data availability. While all principles are considered, the research contributes in the development and application of an integrated and sequential approach to assess data validity of the options by performing analyses to determine the precision and accuracy of axle load measurements. Within the context of Manitoba, the evaluation reveals that data produced by piezo-quartz and static weigh scales have superior validity, with piezo-quartz data offering better temporal coverage, data availability, and future geographic coverage. Ultimately, the selection of the best option for providing quality axle load data depends on the relative importance of data quality principles for producing data supporting sound pavement designs and infrastructure management decisions.<br>May 2017

Full-scale simulated live load tests were conducted in a controlled laboratory setting using a single-axle frame on 600-mm-inner-diameter reinforced concrete pipe (RCP) and corrugated steel pipe (CSP) when buried in dense, well-graded sand and gravel. Measurements of the RCP at nominal and working forces and beyond are reported for 0.3, 0.6 and 0.9 m of soil cover above the pipe crown. The RCP experienced no cracking when buried at 0.3 m under nominal and working CL-625 and CL-800 single-axle design loads. At these loads, the vertical contraction of the pipe diameter was less than 0.08 and 0.10 mm and the largest tensile strains in the pipe were 75 and 100 με (50-60% of the cracking strain), respectively. A 0.15 (±0.05)-mm-wide axial crack developed at the inner crown in the presence of a 6 kNm/m circumferential bending moment (70% of the theoretical ultimate moment capacity) at the fully factored CL-625 load. This crack did not propagate or widen from 3 series of cyclic load-unload tests. At 1300 kN of applied load the change in pipe diameter was less than 3.5 mm. Increasing soil cover from 0.3 to 0.6 to 0.9 m reduced the circumferential crown bending moment from 6.0 to 3.9 to 2.1 kNm/m, respectively, at 400 kN of axle load. A 1.6- and a 2.8-mm-thick CSP were also subjected to axle loading. No yielding or limit states occurred in the 1.6-mm-thick CSP when buried 0.9-m-deep. However, at 0.6 m of cover a 300 kN axle load caused local yielding at the pipe crown. Increasing soil cover from 0.6 to 0.9 m decreased the vertical diameter change from -3.0 to -1.2 mm and the crown bending moment from 0.7 to 0.2 kNm/m (75% and 20% of the yield moment), respectively, at a 250 kN axle load. Deflections of the thicker CSP were less than the thinner pipe below the CL-625 single-axle load, however further increases in applied load produced a greater response in the thicker pipe, likely due to a haunch support issue. Shallow axle loading produced a greater 3-dimensional response and a larger bending effect in both CSPs.<br>Thesis (Master, Civil Engineering) -- Queen's University, 2012-05-06 15:10:12.754

Tese de doutoramento em Engenharia Civil, na especialidade de Urbanismo, Ordenamento do Território e Transportes, apresentada ao Departamento de Engenharia Civil da Faculdade de Ciências e Tecnologia da Universidade de Coimbra<br>Despite being crucial to the economic and social development of any country or region, road freight transport is one of the players responsible for environmental impact of transport increasing in the last decades. In order to minimise these impacts, heavy vehicles have been evolving. Consequently, road pavement design must keep up with it since a road pavement is designed for a foreseeable heavy traffic flow that will pass on the pavement during its considered life time. The current pavement design procedures convert the heavy traffic flow into a number of Equivalent Standard Axle Load (ESAL) applications. In particular, the Portuguese procedure uses Aggressiveness Factors (AFs) to make that conversion. However, the Portuguese AFs have remained unchanged since at least 1995 and subsequently they are not up-to-date with the evolutions in heavy vehicles. This thesis addresses the development of a methodological framework for AFs (and pavement damage) estimation. For that, axle load spectra are simulated by using a commercial software TruckSIM®. The methodological framework is applied to two case studies, a ‘baseline’ case study and an ‘empty running’ case study. For that, two pavement structures and two trucks are considered. The trucks carry different payload weights and run with different travel speeds over road profiles with different levels of roughness. In the third of a three level-hierarchical approach assumed, an application was created which allows the consideration of the degradation of the Asphalt Concrete (AC) modulus and the roughness growth along the pavement design period. It is used to quantify (a) the effect of the initial International Roughness Index (IRI) value of the road profile on the pavement damage, (b) the effect of the AC modulus degradation on the pavement damage and (c) the effect of the roughness growth on the pavement damage. The results show that the AFs are strongly affected by the truck configuration, the pavement structure, the roughness level of the road profile and the design criterion. For example, the fatigue’s AF for a specific truck running fully loaded at 60 km/h over a road profile with IRI equal to 1 m/km is 53% higher in the thinner structure. The initial IRI value and the amount of AC modulus degradation have a great effect on the pavement damage. The AC modulus degradation can increase the pavement damage, at the end of the considered life cycle, within the range of 136% to 391%. In its turn, the roughness growth can increase the pavement damage within the range of 5% to 18%. The ‘empty running’ case study is intended to show how the methodological framework can be applied to quantify the impact of some transport policies on the pavement damage. When the empty running percentage reduces from 25% to 0%, the pavement damage, at the end of the considered life cycle, increases by more than 26% whichever case is analysed. These results are closely related to the flexible pavement structures, the trucks and the models considered in the analysis. However, the methodological framework developed has the advantage of being easily applied and extendable to other situations.<br>Apesar de ser fundamental para o desenvolvimento social e económico de qualquer região ou país, o transporte rodoviário de mercadorias é um dos responsáveis pelo crescimento do impacto ambiental dos transportes nas últimas décadas. No sentido de minimizar estes impactos, os veículos pesados têm vindo a sofrer alterações. É assim necessário que o dimensionamento de pavimentos rodoviários acompanhe essas alterações, uma vez que um pavimento é dimensionado para suportar um determinado fluxo de veículos pesados que irá solicitar o pavimento ao longo do seu tempo de vida. Os procedimentos de dimensionamento de pavimentos correntemente usados convertem o fluxo de veículos pesados num número equivalente de aplicações de eixos-padrão. Por exemplo, o procedimento usado em Portugal utiliza fatores de agressividade para efetuar essa conversão. No entanto, estes fatores de agressividade permanecem inalterados desde pelo menos 1995, pelo que não têm acompanhado a evolução dos veículos pesados. Esta tese apresenta o desenvolvimento de uma metodologia para estimar fatores de agressividade (e o dano em pavimentos). Neste sentido foram simulados espetros de carga por eixo usando o programa comercial TruckSIM®. A metodologia é aplicada a dois casos de estudo, um caso de estudo de ‘referência’ e um caso de estudo de ‘viagens sem carga’. Para tal, foram consideradas duas estruturas de pavimento e duas configurações de veículos pesados de mercadorias. Os veículos pesados podem transportar cargas com pesos diferentes e circular com velocidades de circulação diferentes sobre pavimentos com diferentes níveis de irregularidade. No terceiro dos 3 níveis da abordagem hierárquica usada, foi criada uma aplicação que permite considerar a degradação do módulo das misturas betuminosas e o aumento da irregularidade do pavimento ao longo do período de dimensionamento. Esta aplicação é usada para quantificar (a) o efeito que a irregularidade inicial do pavimento tem no dano do pavimento, (b) o efeito que a degradação do módulo das misturas betuminosas, ao longo do período de dimensionamento, tem no dano do pavimento e (c) o efeito que o aumento da irregularidade do pavimento, ao longo do período de dimensionamento, tem no dano do pavimento. Os resultados mostram que os fatores de agressividade são fortemente afetados pelo tipo de veículo, pela estrutura do pavimento, pelo nível de irregularidade do pavimento e pelos critérios de dimensionamento considerados. Por exemplo, o fator de agressividade para o critério de fadiga e para um determinado tipo de veículo, que circula completamente cheio a 60 km/h sobre um pavimento com um Índice de Irregularidade Internacional (IRI) igual a 1 m/km, é 53% superior na estrutura delgada. O valor de IRI inicial e o modelo degradação do módulo das misturas betuminosas têm um grande efeito no dano do pavimento. A degradação do módulo pode aumentar os danos, no fim do ciclo de vida considerado, numa percentagem que pode variar entre 136% e 391%. Por sua vez, a evolução da irregularidade pode aumentar o dano do pavimento entre 5% e 18%. O caso de estudo ‘viagens sem carga’ pretende demonstrar a aplicabilidade da metodologia na quantificação do impacto que algumas políticas de transporte podem ter no dano dos pavimentos. Quando a percentagem de viagens sem carga reduz de 25% para 0%, o dano dos pavimentos, no fim do ciclo de vida considerado, aumenta em mais de 26%, seja qual for o caso analisado. Os resultados apresentados estão intrinsecamente relacionados com as estruturas de pavimento, as configurações dos veículos pesados e os modelos considerados na análise. Contudo, a metodologia desenvolvida tem a vantagem de poder ser facilmente utilizada e de poder ser facilmente estendida a outras situações.<br>EMSURE - (CENTRO-07-0224-FEDER-002004)

碩士<br>國立成功大學<br>土木工程學系碩博士班<br>96<br>Abstract Flexible pavement design methods adopted by Taiwan Department of Highway are mostly in accordance with U.S.A.'s method ,American Association of State Highway and Transportation Officials (AASHTO ) designs method. At the same time, it is a easy and convenient design method. Wherever in U.S.A. or international, the design law of Flexible pavement design methods has been changed from traditional experience law into mechanics - experience one (Mechanistic-Empirical Pavement Design Guide, MEPDG). The new design method is expressed with whole axle load distribution other than single equivalent ESAL of 18 kip (80kN ). During the running of 20 years of Taiwan National Department of Highway ,the related traffic character like axle load frequency and truck weight are getting variable with growth of heavy-truck traffic flow. The variety, finally, will cause to influence of design result of pavement thickness. So, it is needed to analyze the variety of those relevant traffic character and to feedback to the administrative system of highway. This research collectes important data regarding the axle load of heavy truck from Taiwan National highways No.1 Gangshan weight station and No.3 Shanhua weight station and Jhutian weight station in recent years.It uses statistics (Non-Parametric Statistic ) to analyze the variety of axle load distribution. The result shows that the load distribution of Gangshan south weight station on National highways No.1 is greatly different from that of Gangshan north weight station .The heavy-vehicle flow on north scale is mostly of semi-trailer, and secondly, the single unit truck . However, the Gangshan south weight station gets opposite result. Obviously, the load of north section is heavier than that of south section . It also compares the variety of static weight station with dynamic one of Shanhua weight station. We find the difference of 4 tons for each heavy-vehicle between static and dynamic weight station. And it always appears normal distribution. Besides, the statistically test of its U11 spatial and temporal variations also shows that most of monthly single axle load distribution are not significant differences. The difference between distributions observed at opposite direction at a site are not significant . To promote stress pavement design method smoothly , this text via long-term collection and statistical method can bring some understanding of variety of traffic character and to build up native axle distribution efficiently.

Within the transit industry it is well known that transit buses have the potential to operate at weights that exceed vehicle weight limits. However, few attempts have been made to date to determine how often this occurs and to what degree. This research characterizes the current transit industry with respect to the regulatory environment, factors that have affected the weight of modern day transit buses, and methods for accommodating transit buses in pavement design. This research then develops and applies a methodology for calculating the in-service weights of standard 40-ft. transit buses using a combination of passenger characteristic data, transit bus curb weight data, and transit ridership data. The findings of this research suggest that the transit bus industry is in a state of competing interests. Weight estimates developed in this research identify that current transit bus models are unable to comply with vehicle weight limits in most jurisdictions even with no passengers on board. Further, these estimates indicate that transit buses have a significant impact on pavements – comparable to those of fully-loaded, five-axle semi-trucks on a per vehicle basis. To date this issue has been addressed in the Canadian Prairie Region by indefinitely granting transit buses overweight permits. However, based on the current state of the transit industry there is little incentive for transit agencies to operate lightweight transit buses and little incentive for transit bus manufacturers to produce lightweight transit buses in order to address pavement and regulatory concerns. Consequently, transit bus axle weight issues in the Canadian Prairie Region are expected to continue in the foreseeable future.<br>October 2015

碩士<br>國立成功大學<br>土木工程研究所<br>86<br>AASHTO剛性鋪面等效軸荷重因子之研究 研 究 生：林聖旋 指導教授：郭振銘 摘 要 目前AASHTO規範為國內剛性鋪面厚度設計常使用的規範之一。 此規範是以單軸8.2 ton(18,000 lb)及胎壓517.3 kPa(75 psi)至565.6 kPa(82 psi)為標準軸重之試驗結果，亦即須先將所有的車軸轉換成相當 於單軸8.2 ton(18 kips)對鋪面所造成損壞的等效軸重因子(ESLF)，再累 積求得設計年限內的等效單軸荷重(ESAL)次數，作為鋪面厚度設計之交通 因子(W18)。若ESLF有稍微的偏差，因龐大交通量之故其設計年限內所累 積下的W18將產生很大的誤差，所設計的鋪面厚度必定有所差距。然而 AASHTO規範的ESLF經驗式僅考慮鋪面版的厚度、車軸種類（單、雙軸）、 車軸重量及鋪面最終服務指標等四項因素而已，且有一部份的ESLF是以外 插的方法得到。　　有鑑於上述之缺失，本研究以電腦模擬現場之方式， 並應用ANAQUS有限元素分析程式去模擬混凝土鋪面及荷重型態以分析其受 力行為。並得一ESLF之迴歸式，同時探討鋪面版厚度、有無荷重傳遞設施 、底層強度、底層厚度、車軸種類及載重大小等各個因子對ESLF的影響。 A Study of Equivalent Single-Axle Load Factor in AASHTO Design Guide for Rigid Pavement Chen-Ming Kuo Sheng-Xuan Lin AbstractNowadays, Guide for Design of Pavement structures by AASHTO is the major reference for rigid pavement design in Taiwan. The main failure of pavement comes from the loads of vehicles. Therefore, if the ESLF(Equivalent Single-Axle Load Factor) varies a little bit, the traffic parameter(W18) accumulated within design period has big deviation because of the huge traffic and it will result in some deviation of the thickness of pavement desingned. This paper models AASHO road tests in three-dimensional finite element method of figure out the slab stresses. Then it uses the experimental formula of ESLF of AASHTO and the common formula (ESLF=(σx／σ18)^c) to figure out c value. After fixing the c value, it will consider the thicknessof the slab, the thickness and strength of the base, with or without dowel bars, the axles loads and thermal loads, and models them in three-dimensional finite element method and matches the formula (ESLF=(σx／σ18)^c) which has a fixed c value to figure out the more properESLF to offer reference for designer of pavement thickness.

Auf der Grundlage der Auswertung von Achslastwägungen auf Bundesautobahnen werden Verfahren zur Bestimmung des dimensionierungsrelevanten Achslastkollektivs auf Straßen ohne Achslastwägungen entwickelt und gegenübergestellt. Im Ergebnis stellt sich das Verfahren mit Erhebung des kompletten Fahrzeugtypkollektivs in situ und anschließender Überlagerung der relativen Fahrzeugtyphäufigkeiten mit standardisierten, fahrzeugtypischen Achslastverteilungen als das geeignetste Verfahren zur Ermittlung des dimensionierungsrelevanten Achslastkollektivs ohne verfügbare Achslastdaten heraus.:1 Einleitung 1.1 Ausgangslage 1.2 Problem- und Zielstellung 1.3 Stand von Wissenschaft und Technik, Literaturrecherche 2 Vorgehensweise 3 Datengrundlage 3.1 Datenbestand 3.2 Datenstruktur 3.3 Plausibilitätsanalyse 3.3.1 Allgemeines 3.3.2 Dimensionierungsrelevante Daten 3.3.3 Informationsrelevante Daten 3.3.4 Datenbestand zur Plausibilitätsanalyse 3.3.5 Methodik der Plausibilitätsanalyse 3.3.6 Definition der Plausibilitätskriterien 3.3.7 Implementierung der Plausibilitätskriterien 3.3.8 Berechnungsalgorithmus 3.3.9 Plausibilitätsfilter 3.3.10 Berechnungsergebnisse und Behandlung unplausibler Daten 3.4 Zusammenfassung 4 Datenauswertung 4.1 Zusammensetzung des Schwerverkehrs 4.2 Häufigkeitsverteilung der Achslasten 4.2.1 Datenbasis und statistische Grundlagen 4.2.2 Grafische Auswertung 4.2.3 Beschreibung mittels statistischer Kenngrößen 4.3 Klassifizierung des qualitativen Achslastniveaus 4.4 Zusammenfassung 5 Dimensionierung der Befestigung nach den Richtlinien für die Standardisierung des Oberbaus von Verkehrsflächen (RStO) 5.1 Allgemeines 5.2 Berechnungsverfahren und Eingangsgrößen 5.2.1 Kriterium Frostsicherheit 5.2.2 Kriterium Tragfähigkeit 5.3 Bemessungsrelevante Beanspruchung und Bauklasse 5.3.1 Gegenüberstellung der Berechnungsergebnisse 5.3.2 Achszahlfaktor 5.3.3 Mittlerer Lastkollektivquotient 5.3.4 Auswirkungen auf die Bauklasse und den Befestigungsaufbau 5.4 Festlegung des Schichtenaufbaus 5.4.1 Schichtenaufbau nach den RStO 01 5.4.2 Schichtenaufbau nach den RStO 12 6 Dimensionierung der Befestigung nach den Richtlinien für die rechnerische Dimensionierung des Oberbaus von Verkehrsflächen mit Asphaltdeckschicht (RDO Asphalt 09) 6.1 Allgemeines 6.2 Berechnungsverfahren und Eingangsgrößen 6.3 Angewandtes Programmsystem zur rechnerischen Dimensionierung 64 6.4 Dimensionierungsberechnungen 6.4.1 Zielstellung 6.4.2 Variation der Achslastklassenbreite 6.4.3 Variation der Achslastverteilung 6.4.3.1 Allgemeines 6.4.3.2 Achslastverteilung auf der Grundlage von Messdaten am Messquerschnitt 6.4.3.3 Achslastverteilung auf der Grundlage standardisierter BAB-Typen 6.4.3.4 Achslastverteilung auf der Grundlage eines reduzierten Fahrzeugtypkollektivs 6.4.3.5 Achslastverteilung auf der Grundlage klassifizierter Fahrzeugtypgruppen 6.4.3.6 Gegenüberstellung der Achslastverteilungen 6.4.3.7 Berechnungsergebnisse 6.4.4 Zusammenfassung und Schlussfolgerungen für die Praxis 7 Ersatzverfahren zur Ermittlung des dimensionierungsrelevanten Achslastkollektivs 7.1 Allgemeines 7.2 Prinzip der Ersatzverfahren zur Ermittlung des dimensionierungsrelevanten Achslastkollektivs 7.3 Ersatzverfahren E1 - Ermittlung des dimensionierungsrelevanten Achslastkollektivs auf der Grundlage des gesamten Fahrzeugtypkollektivs 7.4 Ersatzverfahren E2 - Ermittlung des dimensionierungsrelevanten Achslastkollektivs auf der Grundlage eines reduzierten Fahrzeugtypkollektivs 7.5 Ersatzverfahren E3 - Ermittlung des dimensionierungsrelevanten Achslastkollektivs auf der Grundlage von Fahrzeugtypgruppen 7.6 Ersatzverfahren E4 – Ermittlung des dimensionierungsrelevanten Achslastkollektivs auf der Grundlage der aktualisierten Achslastverteilungen nach den RDO Asphalt 09 7.7 Statistisches Vergleichsverfahren 7.7.1 Allgemeines 7.7.2 Angewandtes statistisches Verfahren 7.7.3 Methodisches Vorgehen 7.8 Standardachslastverteilungen der Fahrzeugtypen nach den TLS 2012 7.9 Praktische Anwendung der Ersatzverfahren 7.9.1 Stichproben im nachgeordneten Straßennetz 7.9.2 Standardachslastverteilungen für Fahrzeugtypen außerhalb der TLS 2012 sowie für Fahrzeugtypen außerhalb der Standardverteilungen 7.9.3 Anwendung des Ersatzverfahrens E1 – Ermittlung des dimensionierungsrelevanten Achslastkollektivs auf der Grundlage des gesamten Fahrzeugtypkollektivs 7.9.4 Anwendung des Ersatzverfahrens E2 – Ermittlung des dimensionierungsrelevanten Achslastkollektivs auf der Grundlage eines reduzierten Fahrzeugtypkollektivs 7.9.5 Anwendung des Ersatzverfahrens E3 – Ermittlung des dimensionierungsrelevanten Achslastkollektivs auf der Grundlage von Fahrzeugtypgruppen 7.9.6 Anwendung des Ersatzverfahrens E4 – Ermittlung des dimensionierungsrelevanten Achslastkollektivs auf der Grundlage der aktualisierten Achslastverteilungen nach den RDO Asphalt 09 7.9.7 Vergleich der dimensionierungsrelevanten Achslastkollektive nach den Ersatzverfahren E1 bis E4 7.9.8 Dimensionierungsberechnungen 7.9.8.1 Dimensionierung des Oberbaus nach den RStO 12 7.9.8.2 Dimensionierung des Oberbaus nach den RDO Asphalt 09 7.9.8.3 Gegenüberstellung der Ergebnisse der Dimensionierung des Oberbaus 7.9.8.4 Bewertung der Ersatzverfahren 8 Zusammenfassung und Ausblick Verzeichnis der verwendeten Abkürzungen Literaturverzeichnis Anlagenverzeichnis Abbildungsverzeichnis Tabellenverzeichnis

Dissertação de Mestrado Integrado em Engenharia Civil apresentada à Faculdade de Ciências e Tecnologia<br>O fluxo de tráfego de veículos pesados é um dos parâmetros que mais influencia o dimensionamento de pavimentos rodoviários. Em Portugal, esse fluxo é convertido num número equivalente de eixos-padrão, através de fatores de agressividade. Contudo, os fatores de agressividade mantêm-se inalterados desde, pelo menos 1995, pelo que se apresentam alheios à evolução que se tem vindo a verificar relativamente à frota de veículos pesados de mercadorias. Adicionalmente, novas metodologias de dimensionamento têm surgido, as quais se baseiam em espetros de carga contruídos através de dados coletados em estações de pesagem dinâmica (WIM – Weigh-in-motion), dados estes que nem sempre estão disponíveis.Com o intuito de superar a indisponibilidade de dados WIM, a presente dissertação avalia o uso da simulação de veículos pesados na definição dos fatores de agressividade. Para o efeito, analisaram-se os veículos que compõem o parque automóvel em Portugal, em termos de pesados de mercadorias. Posteriormente, os veículos que se verificaram ser os mais predominantes foram simulados para diferentes pesos de carga, obtendo-se as cargas aplicadas por cada pneu à estrutura do pavimento. Com essas cargas, calculou-se a agressividade para diferentes pesos de carga, construíram-se regressões e definiu-se uma metodologia que permite o cálculo da agressividade considerando apenas o número de veículos e o fator de carga. Em paralelo, usaram-se dados WIM e calculou-se a agressividade do tráfego coletado num ano. Finalmente, procedeu-se à validação da metodologia, através da comparação da agressividade simulada com a agressividade do tráfego coletado.Do trabalho realizado concluiu-se que os fatores de agressividade determinados através de simulação de veículos eram bastante aproximados dos fatores de agressividade obtidos através dos dados de tráfego coletados. Assim sendo, é possível afirmar-se que a indisponibilidade dos dados WIM pode ser ultrapassada recorrendo à simulação de veículos pesados. O mesmo trabalho permitiu também concluir que a definição de fatores de agressividade é influenciada por diversos parâmetros, dos quais apenas se considerou na presente dissertação o tipo de pneu e a área de contacto pneu-pavimento, o fator de carga e os mecanismos de deterioração.<br>The traffic flow of heavy vehicles is one of the parameters that most influence the design of road pavements. In Portugal, this flow is converted into a number of equivalent standard axle load, through aggressiveness factors.However, the aggressiveness factors have remained unchanged since at least 1995 and have therefore not kept pace with the evolution of the heavy goods vehicle fleet. In addition, new design methodologies have emerged, which are based on load spectra built through data collected in weigh-in-motion (WIM) stations. However, these data are not always available.In order to overcome the unavailability of WIM data, the present dissertation evaluates the use of heavy vehicle simulation to define aggressiveness factors. For this purpose, the Portuguese heavy goods vehicles fleet was analyzed. Subsequently, the most representative fleet’s vehicles were simulated for different load weights, obtaining the loads applied by each tyre to the pavement structure. With these loads, the aggressiveness was calculated for different load weights, regressions were constructed and a methodology was defined that allows the calculation of the aggressiveness considering only the number of vehicles and the load factor. In parallel, WIM data were used and the aggressiveness of the traffic collected in a year was calculated. Finally, the methodology was validated by comparing the simulated aggressiveness with the aggressiveness of the collected traffic.From the work carried out, it was concluded that the aggressiveness factors determined through vehicle simulation were quite close to the aggressiveness factors obtained through traffic data collected. Therefore, it can be stated that the unavailability of the WIM data can be overcomed by using heavy vehicle simulation.The same work also allowed us to conclude that the definition of aggressiveness factors is influenced by several parameters, of which only the tyre type and the tire-pavement contact area, the load factor and the deterioration mechanisms were considered in the present dissertation.