Download or read book Dynamic Impact Factor Evaluation for Short Span Steel Railway Bridges written by Mehrdad Bisadi and published by . This book was released on 2019 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Dynamic Impact Factor (DIF) is widely employed to account for the dynamic amplification effect of moving trains on railway bridges. An accurate DIF provides a safe yet economical basis for new railway bridges and improves the safety rating assessment for existing railway bridges. This thesis investigates the accuracy, reliability and the underlying influence factors for DIF relationships currently used for short span steel railway bridges. Full-scale field monitoring exercises are conducted to measure the dynamic responses of two railway bridges during various train passages. The monitoring results indicate that both railway bridges satisfy the live load deflection limits recommended for railway bridges subjected to low-speed trains. Three-dimensional Finite Element (FE) models are developed for the each of railway bridges. The models are verified against the monitoring results. The verification results show that the models accurately predict the actual dynamic response of the railway bridges. A series of sensitivity analysis is performed using the verified FE models. The analyses investigate the effects of variation in New Zealand train and bridge dynamic characteristics on the mid-span DIFs of the monitored railway bridges. The trains are simulated as moving constant forces. The analysis results show that the train speeds have the largest influence on the DIFs of the railway bridges. Numbers and axle distances of carriages have some effects on the DIFs which these effects depend on corresponding locomotive axle distances. Bridge damping ratios have some influences, and the train axle loads have no effect on the DIFs. Over 100 different train arrangements corresponding to combinations possible in New Zealand are simulated and applied to the each of the FE modes. The mid-span DIFs are evaluated numerically as the simulated train passes over the bridges with different speeds. It is found that the DIF formulas in New Zealand railway bridge guidelines overestimate the dynamic effects of moving trains on the railway bridges. This overestimation approaches 4.2 times the bridge evaluated DIFs. Data mining techniques are employed to generate predictive models which estimate the medians of the simulated DIFs. These predictive models provide users with a reliable prediction of the DIFs for designing or assessing the short span steel railway bridges subjected to train passages with speeds up to 150 km/h.

Download or read book Dynamic Modeling and Field Testing of Steel Railway Bridges written by Peng Lou and published by . This book was released on 2012 with total page 95 pages. Available in PDF, EPUB and Kindle. Book excerpt: In United State, there are a lot of steel railway bridges with non-ballast tracks, which have short and simply supported spans. The majority of similar bridges on the passenger rail systems were built prior to World War II. In New Jersey, freight railcars often utilize a portion of passenger rail systems to complete their trips. Recent increases in railcar weight limits from 263,000 lb to 286,000 lb raised concerns about the passenger rail systems since these bridges were not designed according to the increased railcar weight. Also, the cost to build and maintain new bridges is extremely high. Therefore, impact of the increased railcar weight on those bridges need to be evaluated first to allow the use of passenger lines for the freight travels. The research approach adopted is aiming at evaluating current load-carrying capacity of various types of bridges to provide recommendations for dynamic impact. The impact factor equations specified in AREMA Specifications were based on field tests prior to 1960s. It is important to validate and evaluate the impact factor equation from recent field tests. In this thesis, a 2D dynamic model of train-bridge interaction system was developed. Steel bridge is simulated as a Bernoulli-Euler beam and moving train is modeled as rigid-body. Field measurement was conducted to obtain the strain, deflection, and velocity response of bridge girders under moving trains via wireless Structural Testing System (STS) and non-contact Laser Doppler Vibrometer (LDV). The validity of the presented model was confirmed through comparison with the measured structural response. Impact factor (IF) was then obtained from the validated dynamic model. Train speed, train type, bridge span length, and girder stiffness were considered as the main parameters affecting the IF. The results of this study show that the present AREMA Specifications has a tendency to overestimate the IF at speeds lower than 60 mph for steel bridges.

Download or read book Dynamic Impact Factors for Bridges written by David I. McLean and published by Transportation Research Board. This book was released on 1998 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: This synthesis will be of interest to state department of transportation and consulting bridge, structural, and research engineers. The synthesis describes the current state of the practice for determining dynamic impact factors for bridges. Information for the synthesis was collected by surveying U.S. and Canadian transportation agencies and by conducting a literature search using domestic and foreign sources. This report of the Transportation Research Board documents relevant background and recent information with regard to vehicular dynamic load effects on bridges. It provides details on the basic concepts of bridge dynamics, including identification of the main variables affecting bridge dynamic response. In addition, current code provisions for accounting for vehicular dynamic load effects for new bridge design and load evaluation of existing bridges are reported, including a discussion on the background of the provisions. Finally, a discussion of observed field problems associated with vehicular dynamic load effects, as obtained from the survey, are included.

Download or read book Dynamic Interaction of Train Bridge Systems in High Speed Railways written by He Xia and published by Springer. This book was released on 2017-10-27 with total page 590 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents both the fundamental theory and numerical calculations and field experiments used in a range of practical engineering projects. It not only provides theoretical formulations and various solutions, but also offers concrete methods to extend the life of existing bridge structures and presents a guide to the rational design of new bridges, such as high-speed railway bridges and long-span bridges. Further, it offers a reference resource for solving vehicle–structure dynamic interaction problems in the research on and design of all types of highways, railways and other transport structures.

Download or read book Dynamics of High Speed Railway Bridges written by Raimundo Delgado and published by CRC Press. This book was released on 2008-09-23 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamic behaviour of bridges strongly affects the infrastructure system of high-speed railways, and is a crucial factor in safety issues and passenger comfort. Dynamics of High-Speed Railway Bridges covers the latest research in this field, including: Recently developed dynamic analysis techniques; Train excitations; Design issues fo

Download or read book Design of Modern Steel Railway Bridges written by John F. Unsworth and published by CRC Press. This book was released on 2016-04-19 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: Perhaps the first book on this topic in more than 50 years, Design of Modern Steel Railway Bridges focuses not only on new steel superstructures but also outlines principles and methods that are useful for the maintenance and rehabilitation of existing steel railway bridges. It complements the recommended practices of the American Railway Engineering and Maintenance-of-way Association (AREMA), in particular Chapter 15-Steel Structures in AREMA’s Manual for Railway Engineering (MRE). The book has been carefully designed to remain valid through many editions of the MRE. After covering the basics, the author examines the methods for analysis and design of modern steel railway bridges. He details the history of steel railway bridges in the development of transportation systems, discusses modern materials, and presents an extensive treatment of railway bridge loads and moving load analysis. He then outlines the design of steel structural members and connections in accordance with AREMA recommended practice, demonstrating the concepts with worked examples. Topics include: A history of iron and steel railway bridges Engineering properties of structural steel typically used in modern steel railway bridge design and fabrication Planning and preliminary design Loads and forces on railway superstructures Criteria for the maximum effects from moving loads and their use in developing design live loads Design of axial and flexural members Combinations of forces on steel railway superstructures Copiously illustrated with more than 300 figures and charts, the book presents a clear picture of the importance of railway bridges in the national transportation system. A practical reference and learning tool, it provides a fundamental understanding of AREMA recommended practice that enables more effective design.

Download or read book Design and Construction of Modern Steel Railway Bridges written by John F. Unsworth and published by CRC Press. This book was released on 2017-08-03 with total page 688 pages. Available in PDF, EPUB and Kindle. Book excerpt: This new edition encompasses current design methods used for steel railway bridges in both SI and Imperial (US Customary) units. It discusses the planning of railway bridges and the appropriate types of bridges based on planning considerations.

Download or read book Dynamic Impact Factors Produced by Trains on Long Span Open Deck Steel Truss Railroad Bridges written by David Jacobs and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Long-haul passenger, commuter, and freight railroads are essential to maintaining a thriving economy and environmentally friendly, efficient and less congested transportation system for people and goods, especially in New England, with its many urban areas, industries, and major national defense activities. On Amtrak’s Northeast Corridor between Washington, D.C. and Boston, MA, the busiest passenger rail corridor in the United Sates, there are over 60 long span steel bridges that are more than 100 years old. This situation presents many structural problems, especially overstress in certain members, as well as fatigue. This research focused primarily on two areas. First, developing a finite element (FE) model that can reliably predict the impact, as derived from other bridge responses (displacement and strain), for trains at speeds higher than that currently allowed on these structures. And second, field research to accumulate data on bridge response from each of the train types at various speeds. The research used as test vehicles, two types of Amtrak train sets, Acela higher speed vehicles, and Amtrak conventional Regional train vehicles, as well as Metro-North Railroad’s M8 MU commuter cars. Specific to this research is the type of bridge structure. The model was based on an open deck, long span through truss. This type of bridge is typical of hundreds still in service around the country, and most appreciably over a hundred years old, especially in the Northeast. Field research was conducted on Devon Bridge, a 115-year-old bridge, opened in 1906, over the Housatonic River between Stratford and Milford, Connecticut, and owned by the Connecticut Department of Transportation. The model was developed using STAAD.Pro software. Using the known physical characteristics (axle loads and axle spacing) of the Amtrak and Metro-North vehicles, field tests verified high correlation between actual bridge responses, measured by displacements and strains at various speeds, and those predicted by the model. Thus, the model can be useful in predicting impact values, derived from displacements and strains, from similar types of vehicles on this and other open deck railroad bridges. Additional study and analysis were performed on bridge response under live load to better understand how the relative old age of the test structure, and its long history from use by steam engines and heavy freight trains, effect certain truss members’ response. Particular investigation was performed on the eyebars, which are used as counter diagonals and lower chord members in the truss. Results from this investigation were compared to tests performed several years earlier, and analysis is presented for why some differences appear. A thorough review was also performed contrasting railroad bridges design impact requirements used in countries around the world. The knowledge gained from this research can be applied to other railroad bridges of this type, carrying comparable conventional passenger cars and MU transit cars.

Download or read book Evaluation of Dynamic Impact Factors for Steel Highway Bridges written by Sylvester E. Uwanaka and published by . This book was released on 1989 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Damping Factors and Dynamic Stresses in a Simple Span Steel Railway Bridge written by Charles Tyrrell West and published by . This book was released on 1946 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Durability of Bridge Structures written by Khaled Mahmoud and published by CRC Press. This book was released on 2013-09-12 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt: On Thursday evening, May 23, 2013, the Interstate 5 Bridge over the Skagit River in Washington state collapsed due to impact by an oversize truck, dumping vehicles and people into the water. Fortunately, the bridge is located in a rural area and nobody was killed in the accident, but three people were rescued after their cars plunged into the frigid water of the Skagit River. According to Washington state officials, the bridge was inspected last year and was not structurally deficient, but collapsed because of apparent impact from an oversize truck. Nevertheless, the collapse of the steel truss bridge renewed appeals for greater investment in the nation’s aging infrastructure. These appeals are echoed throughout the bridge engineering community worldwide, as the condition of deteriorated bridges worsens with increasing traffic loads combined with lack of proper maintenance. Bridge engineers from different countries shared their experience toward achieving durable bridge structures, during the 7th New York City Bridge Conference, held on August 26-27, 2013. This book contains select papers that were presented at the conference. These peer-reviewed papers are valuable contributions and of archival quality in bridge engineering.

Download or read book Dynamic Stresses in Short Span Railway Bridges written by Gerard B. Chitty and published by . This book was released on 1990 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Railway Age written by and published by . This book was released on 1941 with total page 1468 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dynamic Analysis of Steel Railway Bridge Subjected to Train Loads written by Rahel Delelegne Shibeshi and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this research a single span simply supported steel truss railway bridge is analyzed when subjected to train loads. The study was conducted by using three different methodologies namely modal analysis using three dimensional finite element models of a bridge based on As-built drawn from scratch; a time history analysis and field measurement on an existing bridge. The finite element models of the bridge were modeled using two methodologies; using beam and shell elements. A time history analysis involves developing an equation of motion for the forced and free vibration of the bridge when subjected to both a single- and successive train loads. The dynamic responses studied include the displacement, acceleration and natural frequency of the bridge which were compared for different train speeds, span length, and the mass of the bridge. Field measurement was conducted using accelerometers and displacement transducers which were mounted on a self-designed mounting section.

Download or read book Investigation of the Effect of Speed on the Dynamic Impact Factor for Bridges with Different Entrance Condition written by Brent M. Phares and published by . This book was released on 2016 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamic interaction of vehicles and bridges results in live loads being induced into bridges that are greater than the vehicle's static weight. To limit this dynamic effect, the Iowa Department of Transportation (DOT) currently requires that permitted trucks slow to five miles per hour and span the roadway centerline when crossing bridges. However, this practice has other negative consequences such as the potential for crashes, impracticality for bridges with high traffic volumes, and higher fuel consumption. The main objective of this work was to provide information and guidance on the allowable speeds for permitted vehicles and loads on bridges .A field test program was implemented on five bridges (i.e., two steel girder bridges, two pre-stressed concrete girder bridges, and one concrete slab bridge) to investigate the dynamic response of bridges due to vehicle loadings. The important factors taken into account during the field tests included vehicle speed, entrance conditions, vehicle characteristics (i.e., empty dump truck, full dump truck, and semi-truck), and bridge geometric characteristics (i.e., long span and short span). Three entrance conditions were used: As-is and also Level 1 and Level 2, which simulated rough entrance conditions with a fabricated ramp placed 10 feet from the joint between the bridge end and approach slab and directly next to the joint, respectively. The researchers analyzed and utilized the field data to derive the dynamic impact factors (DIFs) for all gauges installed on each bridge under the different loading scenarios.

Download or read book Impact in Highway Bridges written by Charles Frank Scheffey and published by . This book was released on 1951 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Simple Analysis of the Effect of Construction Materials on Bridge Impact Factors written by M. L. Peterson and published by . This book was released on 1999 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: