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Optimum design of composite prestressed concrete girder railway bridges
No full textThis paper deals with the formulation of design optimisation of pretsressed concrete bridges. The bridge is of a slab-on-girder type, hence modeled as an equivalent orthotropic plate. The whole bridge system is considered as a simply supported right angle plate. Following linear elastic behaviour, the governing fourth order differential equation of the plate for patch load is solved in order to find out load distribution on the girders forming the bridge as well as the deflections and internal forces at critical sections of the whole bridge. The optimisation problem is formulated for various cross sectional geometries including rectangular, symmetrical I, unsymmetrical I, box, T and inverted T sections. The design variables are the main cross sectional dimensions, prestressing force and tendon eccentricity. The objective function comprises the cost of concrete material, formwork and prestressing steel tendons. The constraint functions are set to satisfy design requirements as per British Standards for bridges (BS 5400). Nonlinear optimisation method based on sequential unconstrained minimisation technique (SUMT) is employed to achieve optimum bridge configuration for specific design parameters of span length, concrete compressive strength and railway loading patterns. A purpose built computer program is set up to carry out the solution of the design optimisation problem efficiently in terms of time and effort. A typical example of unsymmetrical I-section having a small bottom flange as compared to the top flange width with composite deck effect is presented. The results show that the total cost increases as the span increases due to the increase of the initial prestressing force. Furthermore, the total cost decreases as the concrete compressive strength increases in spite of the increasing of the prestressing force. This is due to decrease of the overall depth, top and bottom flange widths, hence leading to a smaller girder size. Such finding will encourage engineers to adopt high strength concrete for bridges as it will help reducing not only the initial cost but also the life cycle cost of the bridge over its entire life
Maximum dynamic stress on bridges traversed by moving loads
No full textMost current research on dynamic effects due to traffic load on simply supported bridges focuses on the mid-span section of the bridge, since this location corresponds to the worst static bending moment. However, the maximum total moment allowing for dynamics, may differ considerably from the maximum moment at mid-span. This paper shows how the maximum can occur in a section relatively far from mid-span with a significant difference in magnitude.Other funderJournal websitewww.bridgesjournal.comEuropean 6th Framework Programme ARCHES (Assessment and Rehabilitation of Central European Highway Structures)Publisher requires the journal URL to appear on the record: www.bridgesjournal.com. Could use Description web link: Journal website as in http://hdl.handle.net/10197/2437? - AV 1/11/2010 au ke SB. 15/11/'1
Durable Timber Bridges - Final Report and Guidelines [Elektronisk resurs]
No full textThis is the final report from the project DuraTB - Durable Timber Bridges. The goal of the project was to contribute to the development of sustainable timber bridges by making guidelines for moisture design and developing new and improved bridge concepts and details in terms of durability and maintenance aspects.In this report the analyzes, surveys, results and guidelines are described. More detailed descriptions are referred to the many publications that the project has delivered.The research leading to these results has received funding from the WoddWisdom-Net Research Programme which is a transnational R&D programme jointly funded by national funding organisations within the framework of the ERA-NET WoodWisdom-Net 2.</p
Alternative Solutions to Meet the Service Needs of Low Volume Bridges in Iowa; TR-452, June 2004
No full textThere is a nationwide need for a safe, efficient and cost effective transportation
system. An essential component of this system is the bridges. Local agencies perhaps
have an even greater task than federal and state agencies in maintaining the low
volume road (LVR) bridge system due to lack of sufficient resources and funding.
The primary focus of this study was to review the various aspects of off-system bridge
design, rehabilitation, and replacement. Specifically, a reference report was developed
to address common problems in LVR bridges. The source of information included
both Iowa and national agencies. This report is intended to be a “user manual” or
“tool box” of information, procedures and choices for county engineers to employ in
the management of their bridge inventory plus identify areas and problems that need to
be researche
The two bridges
No full textAs in "Texas Coming In" (no. 1844-28), a bridge over Salt River is the central motif, making the difference between the Whigs' successful crossing to the "Presidential Chair" and the disastrous route taken by the Democrats. The artist shows Whig candidates Clay and Frelinghuysen crossing a sturdy, modern "People's Bridge." In contrast, Democrats Thomas Hart Benton, George M. Dallas, and James K. Polk tumble from a rotting "Loco Foco Bridge" into Salt River. Benton is laden with a heavy bag or knapsack of "Mint Drops." Polk carries another sack marked "Annexation Texas," naming a major issue in the campaign. A sign on the bridge reads: "All persons are forbid going over this bridge faster than a slow walk." (The People's Bridge on the other hand is "adapted to swift travelling.") Party leader Martin Van Buren is already neck-deep in the water below, and Democratic patriarch Andrew Jackson tries to support part of the collapsing span on his back at right. Benton: "Alas! we were loaded too heavy. I forgot the old bridge was rotten." Van Buren: "I do believe that I shall never get out. I am stuck fast in the mud like a stationary buoy."Entered . . . 1844 by J. Baillie.Lith. & pub. by James Baillie 33 Spruce St. N.Y.Lithography and print coloring on reasonable terms.Signed: H. Bucholzer.The Library's impression of "The Two Bridges" was deposited for copyright on June 26, 1844.Title appears as it is written on the item.Weitenkampf, p. 73.Forms part of: American cartoon print filing series (Library of Congress)Published in: American political prints, 1766-1876 / Bernard F. Reilly. Boston : G.K. Hall, 1991, entry 1844-23
Building bridges
No full textTitle from cover.; "Conference Regarding the Employment of Ex-Offenders"--Leaf 4.; "James Austin, Ph. D., George Washington University, Michael Jacobson, Ph. D., John Jay College of Criminal Justice"--Leaf 3.; "Submitted to: Representative William Dyson, Chair, Appropriations Committee, Connecticut General Assembly."; "Herbert Welte Hall, Central Connecticut State University, New Britain, CT."; "January 15, 2003."; " ... final report and addendum for the Building Bridges: From Conviction to Employment conference held on January 15, 2003"--Letter of transmittal.; Accompanied by Addendum (13 p. ; 28 cm.), prepared by the General Assembly's Legislative Program Review and Investigations Committee; Includes bibliographical references
Prevention and Control of Influenza; Recommendations of the Advisory Committee on Immunization Practices (ACIP)
No full textprepared by Carolyn B. Bridges, Keiji Fukuda, Timothy M. Uyeki, Nancy J. Cox, James A. Singleton.Includes bibliographical references (p. 24-31).1/13/2014JCSmit
Personal Involvement in early US Cable-Stayed Bridges
No full text<p>The personal involvement of the author in the early US cable-stayed bridges is outlined, including the Pasco and Huntington concrete bridges and the Burlington and Fred Hartman composite bridges.</p></jats:p
The Rise of the Scientific Soldier as Seen Through the Performance of the Corps of Royal Engineers During the Early 19th Century
No full textThe second half of the 18th century saw the formation of the first establishments
to provide formal training to officers prior to receiving their first commission.
The first school, the Royal Military Academy, was formed in 1741 by the Board
of Ordnance to train Artillery and Engineer Officers. It was 1800 before the
army formed a similar establishment and the building blocks were in place for
the creation of the Scientific Soldier.
This thesis will look at the formation of the Royal Military Academy and look at
the training that officers received with a focus on those officers destined to
serve during the Peninsular War. The complementary roles and training of the
Royal Military Artificers and the eventual formation of the School of Military
Engineering will be described.
A thorough review will then be undertaken of the officers in the Royal
Engineers, the numbers, their background, the locations they served in and the
tasks they carried out.
A new review of the sieges during the war will be completed using unpublished
material. The other roles undertaken by the Royal Engineers in the Peninsular
War will be fully investigated and described. These roles are more
comprehensive than has been commonly understood and will demonstrate the
contribution of the educated officer to the war.
The thesis will conclude by looking at the impacts of the post-war peace on
military education
A spatio-temporal cluster analysis of structurally deficient bridges in the contiguous USA
No full textThe disease surveillance software SaTScan™ is used to identify spatial and space-time clusters of counties with unusually high counts or rates of SD bridges. Initially, a descriptive data analysis of over 600,000 bridges, on which data were available for 2017, identified the kind of material and design of all bridges. This was followed by analyzing data on SD bridges for the 3108 counties. The clusters were tested for significance with Monte Carlo study to designate significant SD clusters. While the purely spatial analysis was based on data for 2017, the spacetime analysis used data for the years 2006–2017. A Negative Binomial regression model was used in addition to a cluster analysis. Regression analysis was performed to adjust SD counts for several covariates or risk factors. This study identified counties with high rates of SD bridges as rural counties with old bridges where there is cold weather and low daily traffic.Journal ArticleFinal article publishe
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