5,273 research outputs found
Modelling Extreme Traffic Loading on Bridges Using Kernal Density Estimators
No full textInnovations on Bridges and Soil-Bridge Interaction (IBSBI 2011), Athens, Greece, October 13-15, 2011Kernel density estimators are a non-parametric method of
estimating the probability density function of sample data. In this paper, the
method is applied to find characteristic maximum daily truck weights on
highway bridges. The results are then compared with the conventional
approach.Deposited by bulk impor
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
Experimental determination of dynamic allowance for traffic loading in bridges
No full textTransportation Research Board 89th Annual Meeting, Washington DC, 2010-1-10 to 2010-1-14Bridge codes adopt values for dynamic allowance in traffic load models that are necessarily conservative
to cover for an entire range of bridges with different mechanical characteristics, boundary conditions, and the large
number of uncertainties associated to the vehicle-bridge interaction problem. A further level of conservatism occurs
due to the independent manner in which the governing static load and the corresponding allowance for dynamics are
specified. In particular, certain bridges are not susceptible to high levels of vehicle-bridge interaction when loaded
by a critically heavy vehicle or a critical combination of vehicles. Recent advances in Bridge Weigh-In-Motion
technology allow not only to collect information on the weights, spacings and speeds of the traffic loads traversing a
bridge, but also to separate the maximum static strain from the total measured strain using a filtering procedure. In
this paper, maximum static and total load effects are collected and analysed for three different sites as part of the
European project ARCHES (6th RTD framework programme). Bridge measurements are used to discuss the
dynamics of the most frequent truck classes and the entire traffic sample. The measurements reveal a decrease in
percentage increment in dynamics and a reduction on the variability of the dynamic increment as the static load
effect increases. This phenomenon can be of particular relevance in the assessment of the dynamics of extreme
loading cases.Deposited by bulk impor
Feasibility Study of Strengthening Existing Single Span Steel Beam Concrete Deck Bridges; HR-214, June 1961
No full textIowa has the same problem that confronts most states in the United States: many bridges constructed more than 20 years ago either have deteriorated to the point that they are inadequate for original design loads or have been rendered inadequate by changes in design/maintenance standards or design loads. Inadequate bridges require either strengthening or posting for reduced loads. A sizeable number of single span, composite concrete deck - steel I beam bridges in Iowa currently cannot be rated to carry today's design loads. Various methods for strengthening the unsafe bridges have been proposed and some methods have been tried. No method appears to be as economical and promising as strengthening by post-tensioning of the steel beams. At the time this research study was begun, the feasibility of posttensioning existing composite bridges was unknown. As one would expect, the design of a bridge-strengthening scheme utilizing post-tensioning is
quite complex. The design involves composite construction stressed in an abnormal manner (possible tension in the deck slab), consideration of different sizes of exterior and interior beams, cover-plated beams already designed for maximum moment at midspan and at plate cut-off points, complex live load distribution, and distribution of post-tensioningforces and moments among the bridge beams. Although information is available on many of these topics, there is miminal information on several of them and no information available on the total design problem. This study, therefore, is an effort to gather some of the missing information, primarily through testing a half-size bridge model and
thus determining the feasibility of strengthening composite bridges by post-tensioning. Based on the results of this study, the authors anticipate that a second phase of the study will be undertaken and directed toward strengthening of one or more prototype bridges in Iowa
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 Influence of Correclation on the Extreme Traffic Loading of Bridges
No full textBridge Maintenance, Safety and Management (IABMAS'10) the Fifth International IABMAS Conference, Philadelphia, USA, 11-15 July 2010Accurate traffic loading models based on measured data are essential for the accurate assessment
of existing bridges. There are well-established methods for the Monte Carlo simulation of single lanes
of traffic, and this can easily be extended to model the loading on bridges with two independent streams of
traffic in opposing directions. However, a typical highway bridge will have multiple lanes in the same direction,
and various types of correlation are evident in measured traffic. This paper analyses traffic patterns using
multi-lane WIM data collected at two European sites. It describes an approach to the Monte Carlo simulation
of this traffic which applies variable bandwidth kernel density estimators to empirical traffic patterns of vehicle
weights, gaps and speeds. This method provides a good match with measured data for multi-truck bridge
loading events, and it is shown that correlation has a small but significant effect on lifetime maximum load effects.Deposited by bulk impor
Use of Railroad Flat Cars for Low-Volume Road Bridges; TR-421, August 1999
No full textIn an attempt to solve the bridge problem faced by many county engineers, this
investigation focused on a low cost bridge alternative that consists of using railroad flatcars (RRFC) as the bridge superstructure. The intent of this study was to determine whether these types of bridges are structurally adequate and potentially feasible for use on low volume roads. A questionnaire was sent to the Bridge Committee members of the American Association of State Highway and Transportation Officials (AASHTO) to determine their use of RRFC bridges and to assess the pros and cons of these bridges based on others’ experiences. It was found that these types of bridges are widely used in many states with large rural populations and they are reported to be a viable bridge alternative due to their low cost, quick and easy installation, and low maintenance.
A main focus of this investigation was to study an existing RRFC bridge that is located in
Tama County, IA. This bridge was analyzed using computer modeling and field load testing. The dimensions of the major structural members of the flatcars in this bridge were measured and their properties calculated and used in an analytical grillage model. The analytical results were compared with those obtained in the field tests, which involved instrumenting the bridge and loading it with a fully loaded rear tandem-axle truck. Both sets of data (experimental and theoretical) show that the Tama County Bridge (TCB) experienced very low strains and deflections when loaded and the RRFCs appeared to be structurally adequate to serve as a bridge superstructure. A calculated load rating of the TCB agrees with this conclusion. Because many different types of flatcars exist, other flatcars were modeled and analyzed. It was very difficult to obtain the structural plans of RRFCs; thus, only two additional flatcars were analyzed. The results of these analyses also yielded very low strains and displacements. Taking into account the experiences of other states, the inspection of several RRFC bridges in Oklahoma, the field test and computer analysis of the TCB, and the computer analysis of two additional flatcars, RRFC bridges appear to provide a safe and feasible bridge alternative
for low volume roads
Structural modelling of suspension bridges with particular reference to the humber bridge
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The purpose of this research was to investigate the parameters that influence the structural behaviour of a specific suspension bridge, The Humber Bridge.
Three finite element computer models of increasing complexity were created for the analyses. They were validated against field measurements for both static and dynamic loading, and good correlation was obtained.
The programs were used to
a) Assess the integrity of the bridge as a whole were three failures of certain individual elements, such as a hanger falling under vehicle impact;
b) Determine the influence of the sizing of individual components, such as deck plate thickness or main cable diameter, on overall behaviour;
c) ascertain the capability of the structure to cope with loading (traffic, wind orthermal), above the original design values; and
d) consider the performance of the bridge had other configurations of hangers been adopted in the original design.
From the results of this work, recommendations are made which could influence the future design of long-span suspension bridges
Vibration of railway bridges in the audible frequency range
No full textThe noise level associated with a train travelling on a bridge is normally greater than that for a train travelling on plain track. It is sometimes the bridge noise that causes the highest levels of disturbance to people in the vicinity or triggers action underregulations such as the Environmental Noise Directive. Consequently, there is a need to study means of predicting noise levels from proposed bridges, noise controlmeasures for existing structures and principles of low-noise bridge design.This thesis describes a programme of work in which an existing calculation model for bridge noise and vibration has been tested and alternative calculation methods havebeen developed where required. The existing model is based on analytical models for wheel-rail interaction and the calculation of the power input to the bridge. Theresponse of the various component parts of the bridge for this power input is found using a simplified SEA scheme.In this work, the existing model has been tested against measurements made on railway bridges and the results of an advanced method of structural analysis, theWaveguide Finite Element (WFE) method. This method is well-suited to modelling some important types of railway bridge. Specifically, it allows a numerical modellingapproach to be used up to higher frequency than conventional Finite Element methods. It has been found to offer some significant advantages over the existingbridge noise model, particularly for concrete-steel composite bridges and concretebox-section viaducts.The track support structure has an important influence on bridge noise and vibration, through its role in the transmission of vibration from the rail to the bridge. Laboratory measurements have been made in this work to characterise the vibration transmissionproperties of two important types of track support structure on bridges; ballasted trackand two-stage resilient baseplate track. Improved methods of modelling the dynamic behaviour of these track forms have been developed from the measurements, whichcan be used in calculation models for both bridge noise and also for rolling noise.<br/
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