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Fatigue design of cast steel nodes in tubular bridge structures

Haldimann-Sturm, S. C.; Nussbaumer, A.
Fonte: Elsevier Science Publicador: Elsevier Science
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.34%
Due to their aesthetic and structural advantages, tubular space truss structures are enjoying increasing popularity in modern bridge construction. The use of cast steel nodes for the joints between the circular hollow section members is also becoming increasingly popular. The fatigue design of such joints, however, requires additional knowledge with respect to their fatigue resistance. Previous experimental investigations showed very clearly that the fatigue behaviour is governed by the welds between the casting stubs and the hollow section members. This paper presents a methodology for the determination of allowable initial sizes of casting defects as a function of the required fatigue resistance of the welds. The relative influence of the main parameters is quantitatively discussed and recommendations for design are given.; http://dx.doi.org/10.1016/j.ijfatigue.2007.03.007

Experimental study on the fatigue behaviour of welded tubular K-joints for bridges

Schumacher, Ann; Nussbaumer, Alain
Fonte: Elsevier Science Publicador: Elsevier Science
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.45%
Fatigue tests were carried out on welded circular hollow section K-joints typical to bridges. The tests specimens were large-scale (approximately 9 m long and 2 m high) trusses loaded in the plane of the truss. Measured member stresses showed that a significant proportion of the load in a truss member may be due to bending, underlining the importance of considering correctly this load case in the design of these structures. Measured hot-spot stresses in the joints were compared with hot-spot stresses calculated using the current design guidelines. It was found that the measured values are considerably lower than the calculated values, calling into question the applicability of the design guidelines to these types of (bridge) structures. The S–N fatigue results from the current study, on the other hand, showed that the fatigue resistance of the joints that were tested is lower than the corresponding S–N design curves. This means that when the considerably higher calculated hot-spot stress range is applied to the corresponding design curve, the predicted resistance is similar to the resistance predicted using the lower measured hot-spot stresses in combination with the lower measured S–N curve too. This has highlighted the importance of relating hot-spot stresses to the appropriate...

Fatigue life and failure modes of crowns systems with a modified framework design

LORENZONI, Fabio C.; MARTINS, Leandro M.; SILVA, Nelson R. F. A.; COELHO, Paulo G.; GUESS, Petra C.; BONFANTE, Estevam A.; THOMPSON, Van P.; BONFANTE, Gerson
Fonte: ELSEVIER SCI LTD Publicador: ELSEVIER SCI LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.45%
Objectives: To evaluate the effect of framework design on the fatigue life and failure modes of metal ceramic (MC, Ni-Cr alloy core, VMK 95 porcelain veneer), glass-infiltrated alumina (ICA, In-Ceram Alumina/VM7), and veneered yttria-stabilized tetragonal zirconia polycrystals (Y-TZP, IPSe.max ZirCAD/IPS e.max,) crowns. Methods: Sixty composite resin tooth replicas of a prepared maxillary first molar were produced to receive crowns systems of a standard (MCs, ICAs, and Y-TZPs, n = 10 each) or a modified framework design (MCm, ICAm, and Y-TZPm, n = 10 each). Fatigue loading was delivered with a spherical steel indenter (3.18 mm radius) on the center of the occlusal surface using r-ratio fatigue (30-300 N) until completion of 10(6) cycles or failure. Fatigue was interrupted every 125,000 cycles for damage evaluation. Weibull distribution fits and contour plots were used for examining differences between groups. Failure mode was evaluated by light polarized and SEM microscopy. Results: Weibull analysis showed the highest fatigue life for MC crowns regardless of framework design. No significant difference (confidence bound overlaps) was observed between ICA and Y-TZP with or without framework design modification. Y-TZPm crowns presented fatigue life in the range of MC crowns. No porcelain veneer fracture was observed in the MC groups...

From Numerical Calculations to Materials Testing Homologation: A Biaxial Fatigue Reliability Prediction Methodology for Structural Components

Spinelli, Daniel Müller; Scozzafave, Caio de Carvalho; Spinelli, Dirceu; Bose Filho, Waldek Wladimir
Fonte: ABM, ABC, ABPol; São Carlos Publicador: ABM, ABC, ABPol; São Carlos
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.36%
This article investigates a fatigue approach conducted from the design phase to testing approval. It considerers modern analytical and experimental tools for structural durability assessment over each development phase for two reference components aiming an early approval methodology validation for a new design. A Finite element analysis procedure was used to set critical spots for measurements minimizing the data acquisition efforts. Based on measured data, strain life calculation was done for two reference components in order to set the release goals for a new design submitted to this approach. An innovative fatigue experimental technique is proposed using component extracted specimens and an edited input cycle loads. Considering the random data from a standard test track and signal proportionality evaluation, while assuming the Brown Miller equation for bi-axial fatigue together with Ramberg-Osgood model, equivalent damage load blocks were edited and used as input for durability assessment on specimens representing the component material. The results for the three parts materials were plotted as Weibull diagram for B10 life estimation. Fatigue life results showed good correlation with the reference parts structural performance thus validating the method as well as approving the new design for production without additional on-vehicle durability testing. The methodology and the fatigue testing proposal is therefore recommended for future applications on similar developments.

Um modelo para previsão de vida à fadiga de juntas soldadas submetidas a carregamentos combinados.; A fatigue life prediction model of welded joints under combined cyclic loading.

Goes, Keurrie Cipriano
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 09/04/2010 PT
Relevância na Pesquisa
36.38%
O presente trabalho teve como objetivo desenvolver uma metodologia prática e confiável para previsão de vida à fadiga de juntas soldadas a cordão pelo processo MIG/MAG, quando estas estão submetidas a carregamentos cíclicos combinados. A máxima tensão linear no pé da solda, região típica de início de trinca, conhecida como hot spot foi utilizada para prever a vida através do método de Fadiga de Alto Ciclo S x N (Tensão x Vida), largamente empregado em códigos de projeto de estruturas soldadas. O Método dos Elementos Finitos foi utilizado para determinação das tensões estruturais resultantes do carregamento e das descontinuidades geométricas presentes nos cordões de solda. A análise de fadiga foi efetuada em ambiente virtual, através de um software (programa) de fadiga capaz de importar as tensões atuantes na região da solda para cada carregamento, combinando-as e obtendo assim a vida à fadiga decorrente da somatória dos diferentes tipos de carregamento ao qual a junta foi submetida. As propriedades monotônicas e cíclicas dos materiais da junta foram obtidas da literatura e de um extenso banco de dados disponível no software de fadiga. Estas propriedades foram ajustadas com base em ensaios de laboratório nas juntas investigadas. A medição ou modelagem das tensões residuais inerentes ao processo de soldagem não fazem parte do escopo deste trabalho. Contudo...

A simple approach to the design of pavements incorporating grouted macadams

Oliveira, Joel; Zoorob, S.; Thom, N. H.; Pereira, Paulo A. A.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2007 ENG
Relevância na Pesquisa
36.38%
Grouted macadams form a semi-flexible class of composites whose behaviour lies somewhere between concrete and conventional asphalt materials, having both excellent rut resistance and a degree of flexibility. This paper presents a series of pavement design computer simulations, based on results obtained from laboratory fatigue and stiffness tests on grouted macadam and conventional asphalt mixtures. The design variables explored include the application of grouted macadams both as surface and binder/base course layers. Comparisons were made with conventional asphalt surface and base course constructions. The resultant stresses, strains and fatigue lives were determined based on four classes of pavement foundations with increasing bearing capacity. In order to simulate traffic loading more realistically, the fatigue characterisation tests carried out on the grouted macadam mixtures incorporated and examined the effect of rest periods on fatigue performance. This paper discusses key findings and includes results in the form of design charts for both composite types. The main conclusion drawn from this project was that lhe incorporation of grouted macadams is likely to provide an economical solution in many pavement design circumstances owing to their superior stiffness and fatigue characteristics.

Balance Fatigue Design of Cast Steel Nodes in Tubular Steel Structures

Wang, Libin; Jin, Hui; Dong, Haiwei; Li, Jing
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
Publicado em 12/09/2013 EN
Relevância na Pesquisa
46.27%
Cast steel nodes are being increasingly popular in steel structure joint application as their advanced mechanical performances and flexible forms. This kind of joints improves the structural antifatigue capability observably and is expected to be widely used in the structures with fatigue loadings. Cast steel node joint consists of two parts: casting itself and the welds between the node and the steel member. The fatigue resistances of these two parts are very different; the experiment results showed very clearly that the fatigue behavior was governed by the welds in all tested configurations. This paper focuses on the balance fatigue design of these two parts in a cast steel node joint using fracture mechanics and FEM. The defects in castings are simulated by cracks conservatively. The final crack size is decided by the minimum of 90% of the wall thickness and the value deduced by fracture toughness. The allowable initial crack size could be obtained through the integral of Paris equation when the crack propagation life is considered equal to the weld fatigue life; therefore, the two parts in a cast steel node joint will have a balance fatigue life.

Drag amplification and fatigue damage in vortex-induced vibrations

Jhingran, Vikas Gopal
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 221 p.
ENG
Relevância na Pesquisa
36.4%
Fatigue damage and drag force amplification due to Vortex-Induced-Vibrations (VIV) continue to cause significant problems in the design of structures which operate in ocean current environments. These problems are magnified by the uncertainty in VIV prediction, particularly with regard to fatigue damage. Although the last fifteen years has seen significant advancement in VIV prediction, important fatigue and drag related questions remain unanswered. This research addresses two important problems. The first is the difficulty in measuring local drag coefficients on long flexible cylinders, excited by VIV. At best engineers are forced to use spatially averaged drag coefficients. This is especially inaccurate when the pipe and flow properties change, either due to partial coverage with VIV mitigation devices, such as strakes or fairings, or shear in the incident current profile. The second problem is the lack of design procedures that account for the effect on fatigue damage due to the higher harmonics in the VIV strain response. To address these problems, two experiments were performed to collect data, the first in October of 2004 and the second in October of 2006. Both of these experiments were designed specifically to collect strain measurements from a densely instrumented pipe undergoing VIV at high mode numbers when subjected to current profiles with varying amounts of shear. Data from these experiments was used to develop a method to extract local drag forces from the measured mean strain. This method...

The development of the welding procedures and fatigue of butt-welded structures of aluminium-AA5383

Calcraft, R. C.; Wahab, Muhammad Abdul; Viano, D. M.; Schumann, G. O.; Phillips, R. H.; Ahmed, N. U.
Fonte: The development of the welding procedures and fatigue of butt-welded structures of aluminium-AA5383 Publicador: The development of the welding procedures and fatigue of butt-welded structures of aluminium-AA5383
Tipo: Artigo de Revista Científica
Publicado em //1999 EN
Relevância na Pesquisa
46.3%
The development of the aluminium shipbuilding industry has seen greater demands put upon the design of faster and larger vessels, particularly in the high speed ferry industry, and increasing loads put on existing vessels. Because of this the fatigue performance of marine grade aluminium alloys has become a limiting factor for design, especially with regard to severe service conditions. Far more information is required, such as the load spectra acting upon the structures and the effects of physical and metallurgical properties, to allow designers to cope with these increased requirements and maximise the performance of the vessels. New grades of marine aluminium alloys have appeared recently, which claimed to improve properties that will aid the designer. CSIRO-MST has begun an in-depth evaluation of the fatigue performance of two marine grade aluminium alloys. Optimisation of welding procedures, post-weld treatments and an understanding of how weld metallurgy relates to the fatigue performance are the major goals. The information produced in this study will allow ship designers and builders to take full advantage of the latest developments in marine grade aluminium alloys. It will also provide the constraints that can be used in the design of larger and faster high speed vessels.; R.C. Calcraft...

A residual strength approach for the fatigue analysis of welded components / Abir Ghosh.

Ghosh, Abir
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado Formato: 97718 bytes; application/pdf
Publicado em //1996 EN
Relevância na Pesquisa
46.08%
The main objective of this research is to develop a fundamentally new fatigue design and assessment procedure which can be used to predict the variation in crack size, strength and inspection periods as well as endurances. Basic fracture mechanics and fatigue procedures are used to illustrate this new technique.; Thesis (Ph.D.)--University of Adelaide, Depts. of Civil & Environmental Engineering and Mechanical Engineering, 1997?; Bibliography: leaves 240-257.; xvii, 274 leaves : ill. ; 30 cm.

Non-linear individual and interaction phenomena associated with fatigue crack growth.

Codrington, John David
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2008
Relevância na Pesquisa
46.41%
The fatigue of materials and structures is a subject that has been under investigation for almost 160 years; yet reliable fatigue life predictions are still more of an empirical art than a science. The traditional safe-life approach to fatigue design is based upon the total time to failure of a virtually defect free component. This approach is heavily reliant on the use of safety factors and empirical equations, and therefore much scatter in the fatigue life predictions is normally observed. Furthermore, the safe-life approach is unsuitable for many important applications such as aircraft, pressure vessels, welded structures, and microelectronic devices. In these applications the existence of initial defects is practically unavoidable and the time of propagation from an initial defect to final failure is comparable with the total life of the component. In the early 1970’s, the aircraft industry pioneered a new approach for the analysis of fatigue crack growth, known as damage tolerant design. This approach utilises fracture mechanics principles to consider the propagation of fatigue cracks from an initial crack length until final fracture, or a critical crack length, is reached. Since the first implementation of damage tolerant design...

Supervised exercise reduces cancer-related fatigue: a systematic review

Meneses-Ech??vez, Jos?? F.; Gonz??lez Jim??nez, Emilio; Ram??rez-V??lez, Robinson
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
46.22%
Question: Does supervised physical activity reduce cancer-related fatigue? Design: Systematic review with meta-analysis of randomised trials. Participants: People diagnosed with any type of cancer, without restriction to a particular stage of diagnosis or treatment. Intervention: Supervised physical activity interventions (eg, aerobic, resistance and stretching exercise), defined as any planned or structured body movement causing an increase in energy expenditure, designed to maintain or enhance health-related outcomes, and performed with systematic frequency, intensity and duration. Outcome measures: The primary outcome measure was fatigue. Secondary outcomes were physical and functional wellbeing assessed using the Functional Assessment of Cancer Therapy Fatigue Scale, European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire, Piper Fatigue Scale, Schwartz Cancer Fatigue Scale and the Multidimensional Fatigue Inventory. Methodological quality, including risk of bias of the studies, was evaluated using the PEDro Scale. Results: Eleven studies involving 1530 participants were included in the review. The assessment of quality showed a mean score of 6.5 (SD 1.1), indicating a low overall risk of bias. The pooled effect on fatigue...

Reference chromosome to overcome user fatigue in IEC

Sáez, Yago; Isasi, Pedro; Segovia, Javier; Hernández, Julio C.
Fonte: Ohmsha; Springer Publicador: Ohmsha; Springer
Tipo: Artigo de Revista Científica Formato: application/pdf
Publicado em //2005 ENG
Relevância na Pesquisa
46.02%
Evolutionary Computation encompasses computational models that follow a biological evolution metaphor. The success of these techniques is based on the maintenance of the genetic diversity, for which it is necessary to work with large populations. However, it is not always possible to deal with such large populations, for instance, when the adequacy values must be estimated by a human being (Interactive Evolutionary Computation, IEC). This work introduces a new algorithm which is able to perform very well with a very low number of individuals (micropopulations) which speeds up the convergence and it is solving problems with complex evaluation functions. The new algorithm is compared with the canonical genetic algorithm in order to validate its efficiency. Two experimental frameworks have been chosen: table and logotype designs. An objective evaluation measures has been proposed to avoid user interaction in the experiments. In both cases the results show the efficiency of the new algorithm in terms of quality of solutions and convergence speed, two key issues in decreasing user fatigue.

ProFatigue: a software program for probabilistic assessment of experimental fatigue data sets

Fernández Canteli, Alfonso; Przybilla, Constanze; Nogal Macho, María; López Aenlle, Manuel; Castillo Ron, Enrique
Fonte: Elsevier Publicador: Elsevier
Tipo: info:eu-repo/semantics/article; publishedVersion
ENG
Relevância na Pesquisa
46.15%
In this work, the software program ProFatigue is presented as a practical tool for derivation of probabilistic S-N and ε-N fields from experimental fatigue data. The program provides an estimation of the parameters involved in the regression probabilistic Weibull fatigue model developed by the authors, allowing an advantageous application of both fields to the stress or strain based approaches in the fatigue design of structures and mechanical components. An extension to the analysis of more complex and varied lifetime problems as thermomechanical, multiaxial and fretting fatigue is possible by adopting suitable damage parameters proposed in the literature as driving force. Application to probabilistic assessment of cumulative damage and further program enhancement are now envisaged.

The Effect of microstructural heterogeneities on the fatigue behaviour of 22MnB5 sheet steel

ABRIVARD, Benjamin; PESSARD, Etienne; MOREL, Franck; DELHAYE, Philippe; GERIN, Benjamin
Fonte: V. Aubin, S. Courtin, A. Koster Publicador: V. Aubin, S. Courtin, A. Koster
EN
Relevância na Pesquisa
56.29%
This work deals with the effect of heat treatment on the fatigue strength of a rear axial beam and aims to propose a methodology suitable and reliable for fatigue design. The rear axial beam is made of sheet metal (22MnB5); the initial microstructure is ferrito-pearlitic and martensitic after the treatment. A vast experimental campaign has been undertaken to investigate the behaviour and more specially the fatigue damage mechanisms observed (with material treated and no treated) under different loading conditions: tension and shear test with different load ratios. To test a sheet on shearing an original test is also used. SEM observations of fatigue failure surfaces, for both heat treated and nontreated specimens, show that the fatigue cracks initiate from inclusions for the specimens loaded in tension. The experiments show that the damage mechanism depends on the applied loading condition: for shear loadings no inclusions are observed at the crack initiation site. A probabilistic approach using the weakest link concept is used to model the fatigue. This approach leads naturally to a probabilistic Kitagawa type diagram, which in this case explains the relationship between the influence of the heat treatment and the microstructural heterogeneities.; Financement Renault

Integration of Residual Stresses in the Design of Mechanical Parts

ELGUEDER, Jawhar; ROUCOULES, Lionel; ROUHAUD, Emmanuelle; COCHENNEC, Florent
Fonte: Arts et Métiers ParisTech Publicador: Arts et Métiers ParisTech
EN
Relevância na Pesquisa
46.26%
This paper presents an original approach in mechanical design to integrate the manufacturing constraints in the final CAD model. An original user-interface is used to integrate manufacturing constraints (for example tolerances) and consequences (for example roughness or hardening) into the model. One of the important consequences of manufacturing processes is the generation of residual stresses into the part. A specific tool is developed and used as a design tool to manage the global evolution of residual stresses in the mechanical part and to obtain the deformed geometry resulting from the applied manufacturing plan. These results can then be used in fatigue simulation. To support the model, a database is used for the integration of residual stresses from stored experimental results, analytical or numerical calculations. An example of a metal sheet laminated and deformed by shot peening is given, the deformed geometry is rebuilt and compared to the experimental results.

Integration of residual stresses in the design of mechanical parts

ELGUEDER, Jawhar; ROUCOULES, Lionel; ROUHAUD, Emmanuelle; COCHENNEC, Florent
Fonte: Trans Tech Publications Ltd Publicador: Trans Tech Publications Ltd
EN
Relevância na Pesquisa
46.14%
Lien vers la version éditeur: http://www.scientific.net/MSF.681.255; This paper presents an original approach in mechanical design to integrate the manufacturing constraints in the final CAD model. A specific user-interface is proposed to integrate manufacturing constraints (for example tolerances) and manufacturing consequences (for example roughness or hardening) into the model. One of the important consequences of manufacturing processes is the generation of residual stresses into the part. An appropriate tool has been developed and used as a design tool to manage the global evolution of residual stresses in the mechanical part and to obtain the deformed geometry resulting from the applied manufacturing plan. These results could eventually be used in fatigue simulation. To support the model, a database is used for the integration of residual stresses from stored experimental results, analytical or numerical calculations. An example of a metal sheet, laminated and deformed by shot peening is given, the deformed geometry is rebuilt and compared to the experimental results.

Teaching durability in automotive applications using a reliability approach

MOREL, Anne; BIGNONNET, André; GERMAIN, Guénaël; MOREL, Franck
Fonte: Springer Publicador: Springer
EN_US
Relevância na Pesquisa
46.34%
Fatigue phenomena, which appear generally below the yield stress, is the cause of more than 80 % of in-service mechanical failures. However, the optimization of the weight and cost when designing mechanical components or structures, linked to improved performance, leads to increasingly stressed components. Therefore a fatigue design approach must be done by the engineer. This paper shows the experience gained over five academic years of teaching fatigue the assessment of automotive components using a reliability approach to predict probability of failure, in the engineering school, Arts et Métiers ParisTech, in France. The choice was made to present a comprehensive fatigue assessment approach using a method, initially developed in the automotive industry and since extended to the aeronautical and mechanical industries. This method is known as the “Stress-Strength interference analysis”. The “Stress” represents the distribution of the driver severity, and the “Strength” represents the distribution of the fatigue strength of all the components. A suspension arm is used to illustrate the approach. The Dang Van multiaxial fatigue criterion is implemented in a Finite Elements Code and a danger coefficient is visualized on the meshed structure. The fatigue analysis is interpreted with respect to the target reliability sought by the car- manufacturer.

Evaluation of expected outcomes of nursing interventions to address the nursing diagnosis of fatigue among patients with congestive heart failure

Assis,Cinthia Calsinski de; Barros,Alba Lúcia Bottura Leite de; Ganzarolli,Marcela Zanatta
Fonte: Escola Paulista de Enfermagem, Universidade Federal de São Paulo Publicador: Escola Paulista de Enfermagem, Universidade Federal de São Paulo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2007 EN
Relevância na Pesquisa
46.27%
OBJECTIVE: To evaluate expected outcomes of nursing interventions to address the nursing diagnosis of fatigue. METHODS: A cross-sectional quasi-experimental design was used. The sample consisted of 30 coronary care unit in-patient with congestive heart failure and fatigue. A specific tool designed for this study was used to collect specific data on outcomes of nursing interventions to manage the nursing diagnosis of fatigue. RESULTS: Nursing interventions to manage patients' fatigue had positive outcomes. CONCLUSION: The use of the nursing process to identify the nursing diagnosis of fatigue, design and implement specific nursing interventions, and evaluate patient outcomes leads to quality nursing care.

Calibrating the steel-members fatigue limit states of the AASHTO LRFD bridge design specifications

Berwick, Benjamin
Fonte: University of Delaware Publicador: University of Delaware
Tipo: Tese de Doutorado
Relevância na Pesquisa
36.45%
Mertz, Dennis R.; It is important to develop and incorporate the knowledge needed to design, construct, and maintain bridges to have the longest service life as possible. Consequently, the fatigue effects on bridges need to be considered and more accurately reflected within the proper bridge design specifications. This thesis describes the calibration process used to select the load and resistance factors for the fatigue limit states of steel bridge members within the AASHTO LRFD Bridge Design Specifications. The process presented within this thesis builds upon work completed as part of the Strategic Highway Research Program No. 2 including the determination of the fatigue load model. The resistance model was developed using available fatigue test data and statistically analyzed using specially developed techniques. Target reliability indices of 1.0 were chosen for all steel detail types based upon a procedure using Monte Carlo simulations and engineering judgment. Load and resistance factors were finally chosen for both Fatigue I and Fatigue II service limit states. The load and resistance factors for the Fatigue I limit state are 2.0 and 1.0 respectively. Similarly, the load and resistance factors are 0.80 and 1.0 for the Fatigue II limit state. We expect the new load and resistance factors for the fatigue service limit states to more accurately capture the fatigue effects of steel bridges and thus increase their service life.; University of Delaware...