Download or read book Fatigue of Aluminum Welds in Canadian Highway Bridges written by Reid Coughlin and published by . This book was released on 2010 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aluminum is the most common metal in the world and its high strength to weight ratio, along with excellent corrosion resistance, can provide efficient solutions for the design and rehabilitation of highway bridge structures. A reduction in a structure's self-weight, when using aluminum, is advantageous for the rehabilitation of existing structures requiring an increased live load capacity and for rapid bridge replacements whereby larger, lightweight components can be installed with limited disruption to traffic. Aluminum structures and components offer the potential for lower life-cycle costs due to the favourable corrosion resistance, allowing for less maintenance over the life of the structure. One significant disadvantage of aluminum is that it is more susceptible to fatigue damage in relation to steel. Being a newer design material for bridge structures, compared to steel, and due to its limited use in the past, limited fatigue testing has been conducted to date. Bridge design codes and specifications employ different approaches for establishing fatigue design (S-N) curves for aluminum structures. The British and European design standards use a two-slope design curve, with a shallower slope in the high cycle range, implying that fatigue damage accumulates at a different rate at lower stress ranges. The Aluminum Association in the United States uses a more conservative approach, assuming a single-slope design S-N curve, by simply extending the curve past the constant amplitude fatigue limit at the initial slope. Limited testing under variable amplitude loading in the high cycle range has been completed to date, where a second slope could be warranted. A new chapter of the Canadian Highway Bridge Design Code (CSA-S6) on aluminum structures is currently under development. The research presented herein provides recommendations regarding the correction factors required for fatigue design of aluminum. In addition, fatigue testing and fracture mechanics analysis studies are performed to further investigate the use of a two-slope S-N curve for the fatigue design of aluminum highway structures.

Download or read book Fatigue Behaviour of Aluminum Friction Stir Welds Under Highway Bridge Conditions written by Shi Hui Guo and published by . This book was released on 2018 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt: Friction stir welding (FSW) is a solid state joining process performed by rotating a cylindrical tool with a short protrusion between the two metal pieces to be joined. The combination of frictional and deformation heating leads to the consolidation of the joint. This welding method is rapidly growing in popularity in many applications, particularly in aluminum alloys for transportation vehicle (rail cars, ships) and bridge applications. Across North America, over 150,000 bridges have been identified as “structurally deficient” or “functionally obsolete”. Since FSW has the potential to have a positive influence on their durability and economics, the Aluminum Association of Canada (AAC) has identified the possibility of replacing promoting aluminum bridge decks as a means of replacing existing deficient concrete decks. However, currently available codes and guidelines for aluminum welded joints only address structures made with conventional welding methods. Therefore, bridge designers are lacking the necessary knowledge to use FSW joints in their designs. The main objective of this thesis is to present a fatigue testing study to support the development of improved “performance-based” code provisions for the quality control and fatigue design of FSW joints by examining the durability of FSW joints with prescribed flaws. In order to obtain the experimental results, various intentionally flawed aluminum FSW samples were fabricated for fatigue testing under constant amplitude (CA) and simulated in-service variable amplitude (VA) loading conditions. A statistical analysis of the results has been performed to assess the influence of the various defect types. It has also been shown how finite element (FE) analysis using the software ABAQUS can be used to assess the influence of the defects on the local stresses within the welded joints. Lastly, it is shown how the fatigue performance of the welds can be predicted using linear elastic fracture mechanics (LEFM). The results of this research will contribute to an improved understanding of the behaviour of imperfect FSW joints under fatigue loading conditions, which simulate in-service vehicular bridge VA loading. The main conclusions of this research include the following: 1) The worst fatigue lives were observed in the specimens with “kissing bond” defects at the weld root (on the order of approximately 1 mm in depth), 2) toe flash, undercut, and worm hole defects, as well as surface improvement by polishing were seen to have a much lower influence on fatigue performance, 3) a novel “lap joint” specimen simulating an extruded bridge deck joint was also observed to fail at the root at a nominal stress level lower than that of a properly-welded butt joint.

Download or read book Fatigue Design of Aluminum Components and Structures written by Maurice L. Sharp and published by McGraw Hill Professional. This book was released on 1996 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt: Focusing on the design challenges associated with using aluminum in such fatigue-critical applications as highway infrastructures, transportation vehicles, automotive suspension systems, and aircraft and machine parts, this reference gives the data and guidelines that mechanical and civil design engineers need to meet these challenges head on.

Download or read book Proceedings of the Canadian Society of Civil Engineering Annual Conference 2021 written by Scott Walbridge and published by Springer Nature. This book was released on 2022-04-13 with total page 583 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book comprises the proceedings of the Annual Conference of the Canadian Society of Civil Engineering 2021. The contents of this volume focus on specialty conferences in construction, environmental, hydrotechnical, materials, structures, transportation engineering, etc. This volume will prove a valuable resource for those in academia and industry.

Download or read book Fatigue Optimization and Quality Control of Friction Stir Welded Joints in Aluminum Highway Bridge Decks written by Mahmoud Trimech and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modern aluminium bridge decks are made from welding several long multi-void extrusions. These welded joints are particularly vulnerable to fatigue failure as they are likely to serve as fatigue crack initiation zones under the effect of cyclic traffic loading. Fatigue is a critical limit state in the design of many short to medium bridges. Traditionally, conventional fusion welding techniques have been used to fabricate aluminium bridge decks. These techniques have been known to produce metallurgical defects and a variety of volumetric defects when used for aluminium structures. These defects have significant effect on the fatigue resistance of welded joints. However, a relatively new welding technology known as friction stir welding (FSW) has emerged and has been suggested for use in infrastructure projects involving aluminium. This innovative welding approach was shown to produce an enhanced weld quality and provide superior control over weld defects to the traditional welding methods. Yet, its use is still limited due to insufficient guidelines in current codes and standards. Key factors such as the fatigue strength of FSW joints and comprehensive quality control criteria, including tolerance levels for commonly occurring defects, remain unstandardized. Furthermore, the numerical models used for fatigue design in aluminium bridges are scarce. As extruded aluminium alloys are increasingly used for bridge construction, there is a growing need for robust numerical models capable of accurately predicting the fatigue behaviour of welded extruded aluminium bridge decks under various load conditions. This doctoral thesis aims to characterize the fatigue behaviour of the most recent FSW configurations in the bridge deck industry, specifically butt-lap FSW joints. The project also seeks to establish tolerance levels for fitup defects associated with bridge decks and investigate their effects on the metallurgical and fatigue performance of butt-lap FSW joints. Lastly, the thesis aims to develop numerical models capable of predicting the fatigue life of FSW aluminium bridge decks under various loading configurations. Experimental tests and numerical analysis were conducted to study the fatigue behaviour of butt-lap FSW joints used in aluminium bridge decks. Large-scale fatigue experiments were designed to provoke fatigue failure in the FSW joint of specimens consisting of a pair of extrusions used in bridge decks. Experimental results indicated that failure initiated from the hooking defect at the tip of the interface in the weld root and propagated to the load application point. Numerical simulations assessed the experimental fatigue data with the effective notch stress (ENS) approach as recommended by the International Institute of Welding (IIW). The results showed that the IIW FAT-71 fatigue design curve conservatively assessed the fatigue data. Fit-up defects, including gaps and tool offsets, were simulated and fabricated experimentally, and their tolerance levels were determined based on a stage prequalification process using FSW quality control code acceptance criteria. Additionally, a welding condition where the FSW tool rotational direction was reversed, was experimentally simulated to investigate which rotational direction provides better fatigue strength for butt-lap FSW joints. Large-scale butt-lap FSW fatigue specimens featuring these welding conditions were fabricated and fatigue-tested. The fatigue data from these tests were statistically analyzed and compared, along with numerical analysis to investigate differences in fatigue strength between welding conditions. Results revealed that the hooking defect played a critical role in fatigue failure mechanisms and fatigue strength of butt-lap FSW joints, with the absence of the hooking defect leading to significant improvements in fatigue strength. A numerical framework for predicting the fatigue life of butt-lap FSW specimens was developed, based on finite element analysis. This framework first accurately predicted the fatigue initiation location and direction using the theory of critical distances (TCD) with both the point method (PM) and line method (LM). Depending on the estimated fatigue initiation location, the fatigue life is then predicted using TCD and linear elastic fracture mechanics (LEFM) models. The numerical framework's efficiency was verified by comparing its predictions with experimental fatigue data from fatigue tests conducted on specimens under different loading configurations, demonstrating reasonable agreement between the predictions and experimental results.

Download or read book Fatigue resistant Design of Cantilevered Signal Sign and Light Supports written by Robert Joseph Dexter and published by Transportation Research Board. This book was released on 2002 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Bridge Dynamics and Deflections and Fatigue in Welded Beams written by National Research Council (U.S.). Highway Research Board and published by . This book was released on 1962 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: Paper 1: Results are presented of an analytical study of the dynamic behavior of simple-span highway bridges traversed by heavy vehicles. Paper 2: Inasmuch as many highway bridges are now being built with elastomeric bearings, it was considered desirable to study the vibration effects of such bridges. Paper 3: The method and procedure used in a digital computer program are described to find horizontal and vertical movements of all joints of a truss, given the member stresses and the structure properties. Paper 4: Results are summarized of tests made to demonstrate the effect of details on the fatigue behavior of welded flexural members.

Download or read book Detection and Repair of Fatigue Damage in Welded Highway Bridges written by Transportation Research Board and published by . This book was released on 1979 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Bridge Engineering Handbook written by Wai-Fah Chen and published by CRC Press. This book was released on 2014-01-24 with total page 574 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over 140 experts, 14 countries, and 89 chapters are represented in the second edition of The Bridge Engineering Handbook. This extensive collection highlights bridge engineering specimens from around the world, contains detailed information on bridge engineering, and thoroughly explains the concepts and practical applications surrounding the subjec

Download or read book Calibration of Fatigue Design Factors and Fatigue Life Reliability of Steel Highway Bridges Using WIM Databases written by Ahmed Mostafa Tawfik Farag and published by . This book was released on 2015 with total page 231 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue life assessment of steel highway bridges is crucial to maintain their safety. Researches are required to quantify uncertainties in loading, resistance, fatigue life prediction and improvement techniques. This study calibrates some fatigue code parameters and models fatigue loading probabilistically using truck data in Canada. Fatigue life improvement by weld toe grinding is assessed experimentally and numerically. Finally, the remaining fatigue life using reliability-based method for cruciform bridge welded detail is predicted. Truck data screening is vital to ensure its quality in calibration and load history prediction. Three different fatigue truck factors and equivalent number of cycles are proposed, using single and dual slope curves, for three bridge span ranges. Span length and fatigue category affected the calibration in short spans and dual slope curves. Using Ontario and Quebec data, probabilistic distributions for stress-range histograms for bridge spans and configurations are developed. Weld toe grinding improved the fatigue life by 60% for category E joint compared to the non-ground specimen. Still, weld imperfections might adverse grinding effect. In deterministic fatigue life prediction, energy-based approach is used for crack initiation, while linear elastic fracture mechanics is used for crack propagation. An initial spherical flaw size of 0.1 mm with no residual stresses leads to the most precise prediction of fatigue resistance for test specimens. For the probabilistic fatigue life prediction of cruciform detail of 6.4 mm fillet weld size, the fatigue life of the concave weld profiles are usually larger than the convex ones. The study developed a method to convert the probabilistic stress range into number of cycles for remaining fatigue life reliability of steel detail. The generated reliability illustrates the fatigue repair and inspection management.

Download or read book Detection and Repair of Fatigue Damage in Welded Highway Bridges written by John W. Fisher and published by . This book was released on 1979 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Estimation of the fatigue life of a welded steel highway bridge from traffic data written by Peter W. Hoadley and published by . This book was released on 1982 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fatigue Assessment of Repaired Highway Bridge Welds Using Local Approaches written by Kasra Ghahremani and published by . This book was released on 2015 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis aims to address a number of unanswered questions regarding repair and fatigue design of welded joints in bridges, including developing and evaluating repair methods for enhancing the fatigue behaviour of web stiffeners in steel bridge girders, using local stress-based methods for evaluating the effectiveness of various repair methods and predicting the fatigue life of welded joints, and studying the effectiveness of high frequency mechanical impact (HFMI) treatments under actual in-service loading conditions in the long fatigue life regime. Along with extensive fatigue testing programs and finite element (FE) analyse studies, a strain based fracture mechanics (SBFM) model is used to predict the fatigue behaviour of repaired welds under realistic loading conditions. Through this research, a methodology is developed for generating structural stress design curves for retrofitted highway bridge welds based on small-scale fatigue experiments, relatively simple and inexpensive fatigue tests of smooth specimens, conventional static materials tests, and laboratory measurements. The idea of retrofitting web stiffener ends in steel bridge girders susceptible to distortion-induced fatigue using adhesively-bonded fibre reinforced polymer (FRP) angles is introduced through this research. The proposed retrofit method is relatively cheap and easy to use and does not require deck removal or any other severe modification to the steel girder. Fatigue tests were conducted on specimens designed to model the conditions in the region between a web stiffener and a flange in a steel girder bridge. Fatigue life increases on the order of several hundred percent were achieved by implementing the proposed retrofit. A coarse FE analysis is used to predict the effectiveness of the proposed retrofit methods in terms of the reduction in the structural stress value. A comprehensive variable amplitude (VA) fatigue testing program and analysis was performed to address a number of concerns raised regarding the use of impact treatments for the fatigue enhancement of welds in the high cycle (> 10 million cycles) domain. The test results are then used to evaluate a number of available recommendations for the fatigue design of impact treated welds. The nominal, structural, and effective notch stress approaches are considered. An SBFM model was lastly used to predict the effectiveness of an HFMI treatment applied to welded details. The model is evaluated using the experimental results and found to be capable of predicting the fatigue lives for both the as-welded and impact treated specimens for all of the studied loading conditions. The idea of using the analytical structural stress S-N curves to predict the fatigue behaviour of welded joints with a similar load carrying condition welds was then explored.

Download or read book Bridge Engineering Handbook Five Volume Set written by Wai-Fah Chen and published by CRC Press. This book was released on 2014-01-24 with total page 3130 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over 140 experts, 14 countries, and 89 chapters are represented in the second edition of the Bridge Engineering Handbook. This extensive collection provides detailed information on bridge engineering, and thoroughly explains the concepts and practical applications surrounding the subject, and also highlights bridges from around the world.Published

Download or read book Highways and Agricultural Engineering Current Literature written by and published by . This book was released on 1941 with total page 730 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1958 with total page 948 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Acceptance Criteria for Ultrasonic Impact Treatment of Highway Steel Bridges written by Rana Tehrani Yekta and published by . This book was released on 2012 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: The need for rehabilitation of bridges has become a critical challenge due to aging and an increase in traffic loads. Many of these bridges are exceeding their design fatigue life. Since many of these bridges are structurally deficient, they need to be rehabilitated or replaced by a new bridge. The most susceptible and weak parts of steel bridges to cracks and fatigue are the welds, due to the presence of high stress concentrations, tensile residual stresses, and imperfections as a result of the welding process. Inspection and repair of welds are difficult and elimination of welded details is not possible in steel bridge construction. Ultrasonic impact treatment (UIT) is a promising and innovative post-weld treatment (PWT) method for improving the fatigue performance of existing welded steel and steel-concrete composite structures such as highway bridges. The fatigue resistance of treated joints is enhanced by improving the geometry of the weld toe, and introducing compressive residual stresses. However, a lack of tools for quality assurance has slowed UIT's adoption by bridge authorities. The current study was undertaken to examine the fatigue performance of structural steel welds subjected to UIT at various levels, including intentional under-treatment and over-treatment, and to relate the fatigue performance of the treated welds to geometric and metallurgical properties measured to control the treatment quality. The last objective was to use the laboratory results to develop acceptance criteria for the quality control of UIT in bridge applications. Fatigue tests of non-load carrying fillet welded attachments were conducted on properly treated, under-treated, and over-treated weld toes. Statistical analyses of the fatigue life data were performed and crack growth was monitored using the alternating current potential drop (ACPD) method. Measurement of local properties (such as weld toe geometry, local hardness, and residual stresses) and examination of the weld toe microstructure were also performed on the untreated and treated welds. The effects of weld toe geometry on the local stresses in the untreated and treated welds were also investigated using elastic finite element analysis (FEA) to obtain the stress concentration factor (SCF) for the different treatment cases and to examine the changes in the SCF for the different weld toe geometries. Based on the statistical analysis performed in this research, the results illustrated that UIT significantly improved the fatigue lives of weld details regardless of the investigated level of treatment quality. The fatigue lives of welded details under constant amplitude (CA) loading and constant amplitude loading with under-loads (CA-UL) were increased up to 30 and 27 times respectively. On average, the fatigue life of the treated weld details was slightly lower under CA-UL than under CA loading. Treatment quality had little impact on the mean of the S-N curves. However, it did impact the design (95% survival probability) S-N curves, with the curve associated with a proper treatment slightly higher than the curves for poor or unknown treatment quality. Local near-surface microhardness and compressive residual stresses were greatest for the over-treated welded details, followed by the properly treated and then the under-treated welded details. Increasing the treatment speed resulted in a greater reduction in the surface microhardness and compressive residual stresses than decreasing the treatment intensity. Finite element analyses showed that changes in weld toe geometry due to UIT can cause a decrease in the SCF near the surface of the treated weld toe. The SCF was the lowest for the properly treated steel specimens and slightly higher for the under-treated specimens. For the over-treated specimens, the SCFs were nearly as high as for the untreated weld. The SCF increases as the thickness of the flange increased up to 19 mm. With further flange thickness increase to 38 mm, the SCF did not change substantially. The work presented herein demonstrated that indent depth measurements from the base metal side, commonly used for quality control, may not identify over-treatment on their own. Indent depth measurements from both the weld and the base metal sides, obtained by measurement of weld toe impressions, offer a good alternative means for identifying over-treatment. However, for identifying under-treatment, indent depth measurements should be used in conjunction with visual inspection for traces of the original weld toe.