201,430 research outputs found
Comparative structural response of two steel bridges constructed 100 years apart
No full textThis paper presents a comparative numerical analysis of the structural behaviour and seismic performance of two existing steel bridges, the Infiernillo II Bridge and the Pinhao Bridge, one located in Mexico and the other in Portugal. The two bridges have similar general geometrical characteristics, but were constructed 100 years apart. Three-dimensional structural models of both bridges are developed and analysed for various load cases and several seismic conditions. The results of the comparative analysis between the two bridges are presented in terms of natural frequencies and corresponding vibration modes, maximum stresses in the structural elements and maximum displacements. The study is aimed at determining the influence of a 1 century period in material properties, transverse sections and expected behaviour of two quite similar bridges. In addition, the influence of the bearing conditions in the global response of the Pinhao Bridge was evaluated
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
Critical Loading Events for the Assessment of Medium-Span Bridges
No full textThe Sixth International Conference
on Computational Structures Technology
Prague, Czech Republic
4-6 September 2002This paper describes the simulation of free-flowing traffic across bridges to predict
the characteristic values for bridge load effects such as bending moment and shear
force. The results of these simulations are then used to demonstrate that, in
predicting the characteristic extreme load effects to which a bridge may be
subjected, it is not sufficient to solely model one- or two-truck presence events. It is
shown that loading events involving three or more trucks may need be included in
the model for short to medium spans. The critical loading events for a particular load
effect are strongly dependent on the span and the shape of the influence line.Deposited by bulk impor
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 use of micro-simulation for congested traffic load modelling of medium- and long-span bridges
No full textThis paper presents a new approach to the modelling of congested traffic loading events on long span bridges. Conventional traffic load models are based on weigh-in-motion data of non-congested traffic, or something similar to a Poisson Arrival process. In neither case do they account for the mixing between lanes that takes place as traffic becomes congested. It is shown here that cars move out from between trucks as traffic slows down which results in a higher frequency of long platoons of trucks in the slow lane of the bridge. These longer platoons increase some characteristic load effects under the slow lane by a modest but significant amount. Micro-simulation, the process of modelling individual vehicles that is widely used in traffic modelling, is presented here as a means of predicting
imposed traffic loading on long-span bridges more accurately. The traffic flow on a congested bridge is modelled using a random mixing process for trucks and cars in each lane, where each vehicle is modelled individually with driver behaviour parameters assigned randomly in a Monte Carlo process. Over a number of simulated kilometres, the vehicles move between lanes in simulated lane-changing manoeuvres. The algorithm was calibrated against video
recordings of traffic on a bridge in the Netherlands. Extreme value statistics of measured strains on the bridge are then compared to the corresponding simulation statistics to validate the model. The micro-simulation algorithm shows that the histograms of truck platoon length are moderately affected by lane changing. This in turn is shown to influence some characteristic load effects of the bridge deck.Higher Education AuthorityCan't locate article. 12M embargo from date of publication. On publication, add citation to set text in Rights field - AV 2/08/2011
Citation added - OR 10/1/201
Effects of Shading by Bridges on Estuarine Wetlands
No full textSalt and brackish water marshes are integral parts of the coastal ecosystem, performing important nutrient cycling and hydrologic functions as well as providing habitat and breeding grounds for many coastal species. Despite their many benefits estuarine marshes have faced continued degradation in the past, which has led to a no net loss policy of these areas. As coastal populations increase so does the need for an improved and more extensive infrastructure including bridging estuarine marshes when building roads. Presently, mitigation is required to alleviate the effects of shading from bridges spanning marshes; however, mitigation is expensive and increases construction costs. Little research has been conducted to quantify the effects of shading by bridges on marsh function and productivity. These effects must be quantified to understand the effect of bridge height and width on the underlying marsh. Should the effects of shading be minimal then mitigation requirements may be reduced, in turn reducing construction costs. The objectives of this project were to determine the effects of bridge height and width on marsh productivity and function, directly assess light attenuation under bridges, and compare the effects of shading on the dominant salt marsh species. Seven different bridges representing various height and width combinations were selected for study. Measurements were taken at random both under and beyond the influence of these bridges. Photosynthetically available light was measured. Plant samples were clipped, dried and weighed to determine aboveground biomass, average stem height, number of stems, number of flowers and basal area. Soil cores were taken to a depth of 30cm and C and N were determined.
Both bridge height and width heavily influence the degree to which shading by bridges effects the underlying vegetation. All plant variables measured show a strong bridge effect at HW ratios less than 0.5 and light attenuation less than 250 umol m-2s-1 under the influence of the bridge. At a HW ratio of 0.68 a bridge effect was still detected although it was greatly diminished. Thirty-two comparisons were made between areas under and outside the influence of bridges having HW ratios greater than 0.7, only four significant differences were detected. Regression analysis shows a clear correlation between marsh productivity and bridge HW ratio, (r2=.95). Data indicates that shading by bridges having HW ratios above 0.7 do not adversely impact the productivity or function of the underlying marsh. The best design is a bridge greater than 9 m over the underlying marsh that is narrow enough to keep the HW ratio greater than 0.7
Análise de alternativas para travessia do rio Itajaí-açu a jusante da ponte localizada no quilômetro 111 da BR-101
No full textTCC (graduação) - Universidade Federal de Santa Catarina. Campus Joinville. Engenharia de Infraestrutura.Esta monografia tem o objetivo de analisar as propostas existentes de obra de arte de engenharia para travessia do rio Itajaí-açu a jusante da ponte localizada no km 111 da BR-101, identificando interações com o plano básico de zona de proteção de aeródromo do Aeroporto Ministro Victor Konder e com a perspectiva de crescimento do complexo portuário do Itajaí, caso estas obras propostas entre 2002 e 2010 fossem implementadas. A metodologia utilizada consiste em pesquisa bibliográfica e documental, para posterior análise de compatibilidade dos projetos referentes as propostas existentes de obras de arte para travessia do rio com o cenário montado tendo como base as informações levantadas na pesquisa bibliográfica e documental. Ademais, apresenta-se um panorama geral da região da foz do rio Itajaí-açu; uma análise do ferry boat utilizado para a travessia, traçando uma estimativa de origem-destino em Navegantes; uma pesquisa bibliográfica de tipos de obra de arte de engenharia que provavelmente devem ser considerados para solucionar o problema apresentado. Quanto aos resultados da presente monografia, verificou-se que as duas propostas de pontes analisadas se estendem acima da superfície de proteção de aeródromo (superfície horizontal interna), além disso, apresentariam interações negativas com perspectivas de desenvolvimento do complexo portuário. Quanto a proposta existente de túnel, se identificou que se o projeto referente a esta proposta fosse implementado, impossibilitaria a dragagem dos canais de acesso ao complexo portuário até a profundidade correspondente ao projeto existente de melhoria dos acessos marítimos ao complexo portuário. Na investigação realizada com as propostas, se propôs o estudo de viabilidade de um túnel ligando os bairros Barra do Rio (Itajaí) e São Domingos (Navegantes), provavelmente na região que está sob as superfícies de proteção de aeródromo chamadas de superfície de aproximação e superfície de transição.This undergraduate thesis aims to analyse existing proposals of engineering structures (bridges and tunnel) to cross Itajaí-açu River downstream of the bridge located in kilometre 111 of BR-101. It identifies interactions that these engineering structures would have with the airfield imaginary surface of Airport Ministro Victor Konder and with the ports of Itajaí-açu River, if one of these proposals, which were proposed between 2002 and 2010, was built in the current scenario. The methodology according to which this analysis was made consists of bibliographic research and research in documents, followed by an analysis of compatibility of the scenario created based on the information gathered in the bibliography research with the projects related to the existing proposals of engineering structures to cross Itajaí-açu River. Furthermore, it was provided a general overview of the region of the mouth of Itajaí-açu River; an analysis of the ferry boat that is currently used to cross the river; an Origin-Destination Survey for the municipality of Navegantes, which was undertaken in the ferry boat; a bibliographic research into types of engineering structures (bridges and tunnels) that probably should be considered to resolve the issue. Regarding the findings of this undergraduate thesis, it was found that the towers relative to the two proposed bridges that were analysed reach above the airfield imaginary surface (inner horizontal surface). In addition, the bridges would interact in a negative fashion with perspectives of development of the ports. Concerning the existing proposal of tunnel, it was found that the tunnel was designed such that the tunnel would preclude the possibility of dredging the maritime access to the ports to the depth set in a current project that aims to improve the maritime access to the ports. Moreover, it was suggested to consider, in a future feasibility study, the possibility of a tunnel connecting the suburbs called Barra do Rio (Itajaí) and São Domingos (Navegantes), probably in the region that is below the airfield imaginary surfaces named approach surface and transitional surface
System behaviour in prestressed concrete T-beam bridges
No full textAbout 70 prestressed concrete T-beam bridges, constructed in the Netherlands between 1953–1977, are still in use today with many located in the main highway network. This type of bridge consists of prefabricated and prestressed T-shaped beams, with an integrated deck slab, cross-beams and transverse prestressing. Even if these bridges are well maintained, two important factors demand the current need for assessment: (1) increased traffic loading and (2) potential lack of shear resistance. Using traditional assessment methods it was concluded that about 50% of these bridges do not fulfil the current design code requirements. However, this does not automatically imply that these bridges are structurally unsafe, since some potentially significant additional load-transfer mechanisms are not taken into account in a traditional assessment. This is strengthened by the observation that, in general, these bridges do not show any signs of distress....Concrete Structure
What is the difference between being a gay person or a transsexual?
No full textThis clipping appeared in the Classifieds and Announcement section of the January 30 and February 6, 1986 issues of The Western Carolinian and was sponsored by Lavender Bridges. Lavender Bridges, an anonymously founded student organization open to all individuals, aimed to promote awareness of lesbian and gay lifestyle, provide lesbian and gay resources, and increase communication with all students and community members. The first organizational meeting took place October 10, 1985 and was officially recognized by the office of Student Development on December 13, 1985. The last mention of the group appeared in the October 10, 1991 issue of the Western Carolinian.Q: What's the difference
between being a gay person or a
transsexual?
A: Most gay people have no
desire to be the opposite gender.
Those individuals who do wish to
be the opposite gender are called
transsexuals and are usually not
gay. Find out more FACTS. Write to:
Lavender Bridges
PO Box 2646
Cullowhee, N.C. 2872
POR FORA DO PRÉ-MODERNISMO
No full textResumo:Este artigo propõe uma reflexão sobre a atuação intelectual do escritor Gustavo Barroso (1888-1959) e de sua relação com o Pré-modernismo brasileiro, considerando categorias como capital cultural e pessoal, conforme Pierre Bourdieu, e que demonstram de que modo o autor se coloca à margem do período, sem ser excluído propriamente.Palavras-chave: Pré-modernismo. Gustavo Barroso. Capital pessoal.Abstract: This article is a reflection about the intellectual activity of writer Gustavo Barroso (1888-1959) and his relationship with Brazilian Pre-modernism, considering categories such as personal and cultural capital, as in Bourdieu, showing how the author was marginalized in the period without being totally excluded.Keywords: Pre-modernism. Gustavo Barroso. Personal capital
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