Traffic loads for the assessment of existing bridges

2021 ◽  
Author(s):  
Vazul Boros ◽  
Roman Lenner ◽  
Alan O'Connor ◽  
Andre Orcesi ◽  
Franziska Schmidt ◽  
...  
Keyword(s):  
Road Traffic ◽  
Traffic Load ◽  
Traffic Loading ◽  
Traffic Loads ◽  
Universal Solution ◽  
Load Effects ◽  
Characteristic Values ◽  
Existing Bridges ◽  
Partial Factor

<p>IABSE TG 1.3 aims to identify appropriate approaches for applications of the partial factor format in assessment of existing bridges. A sub-group was formed to investigate and provide recommendations on updating road traffic loads. Commonly, these are assessed by complex numerical simulations. While this study does not provide a universal solution, it demonstrates by a case study a simple and reasonably conservative way of using simulations to update traffic load effects, meanwhile continuously highlighting the objectives, potential alternatives or pitfalls of simulations. The results indicate that, for the short, single span bridge under consideration, the characteristic values given in Eurocodes provide conservative estimates. The probabilistic model for traffic loading obtained by bridge- and route-specific simulations will yield substantially more favourable reliability levels in comparison to the general model in fib Bulletin 80.</p>

scholarly journals Effects of Traffic Loads and Track Parameters on Rail Wear: A Case Study for Yenikapi–Ataturk Airport Light Rail Transit Line

2020 ◽  
Vol 6 (4) ◽  
pp. 244-264
Author(s):  
Hazal Yılmaz Sönmez ◽  
Zübeyde Öztürk
Keyword(s):  
Traffic Load ◽  
Light Rail ◽  
Rail Transit ◽  
Light Rail Transit ◽  
Independent Variables ◽  
Rail Wear ◽  
Traffic Loads ◽  
Dependent Variables ◽  
Train Speed

AbstractThe aim of this study is to investigate the effects of traffic loads and track parameters, including track curvature, superelevation, and train speed, on vertical and lateral rail wear. The Yenikapi–Ataturk Airport Light Rail Transit (LRT) line in Istanbul was selected as a case study, and rail wear measurements were carried out accordingly. Passenger counts were performed in all wagons of the train on different days and time intervals to calculate the number of passengers carried in track sections between stations regarding traffic loads on the LRT line. Values of traffic load, track curvature, superelevation, and speed were determined for each kilometer where measurements of rail wear were conducted. A multiple linear regression analysis (MLRA) method was used to identify effective parameters on rail wear. Independent variables in MLRA for both vertical and lateral wear include traffic load, track curvature, superelevation, and train speed. The dependent variables in MLRA for vertical and lateral wear are the amount of vertical and lateral wear, respectively. The correlation matrix of the dependent and independent variables was analyzed before performing MLRA. Multicollinearity tests and cross-validation analyses were conducted. According to the results of MLRA for vertical and lateral wear, the obtained coefficients of determination indicate that a high proportion of variance in the dependent variables can be explained by the independent variables. Traffic load has a statistically significant effect on the amount of vertical and lateral rail wear. However, track curvature, superelevation, and train speed do not have a statistically significant effect on the amount of vertical or lateral rail wear.

scholarly journals Investigation of Traffic Loading Effects for Different Codes on Medium- and Small-Span Girder Bridges in China

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Qingfei Gao ◽  
Biao Wu ◽  
Jun Li ◽  
Kemeng Cui ◽  
Chuang Xu
Keyword(s):  
Bridge Engineering ◽  
Traffic Load ◽  
Bending Moments ◽  
Original Design ◽  
Traffic Loading ◽  
Simply Supported ◽  
Girder Bridges ◽  
Loading Effects ◽  
Existing Bridges ◽  
Structure Evaluation

With increasing traffic volume, the traffic load grade given by design codes has gradually increased. For new bridges, there is no problem, and the traffic load can be met through the requirements of the new code. However, for existing bridges, there is a lack of uniform standards on whether they can continue to be used. It is not clear whether these bridges will be judged according to the new code or the original design code. The traffic loading effects of different codes on medium- and small-span girder bridges in China are investigated in this study. Three codes are introduced: JTJ 021-89, JTG D60-2004, and JTG D60-2015. Simply supported girder bridges and continuous girder bridges are discussed. The traffic loading effects calculated based on JTG D60-2015 are significantly larger than those calculated based on JTJ 021-89. For simply supported girder bridges, most of the differences range from 20% to 40%, and the maximum value is almost larger than 60%. For continuous girder bridges, most of the differences in the positive bending moments are concentrated in the 20%∼40% range, while the differences in the negative bending moments range from 10% to 20%. Therefore, the differences in traffic loading effects calculated based on various codes cannot be ignored in actual bridge engineering. The conclusion in this study can provide a basis for bridge structure evaluation and life prediction.

scholarly journals Impact of Traffic Load Randomness on Fatigue of Steel Bridges

2020 ◽  
Vol 15 (5) ◽  
pp. 21-44
Author(s):  
Adam Wysokowski
Keyword(s):  
Road Traffic ◽  
Steel Bridges ◽  
Traffic Load ◽  
Steel Bridge ◽  
Traffic Loads ◽  
Fatigue Durability ◽  
Vehicle Velocity ◽  
Bridge Structures ◽  
Heavy Goods Vehicles

The article considers the influence of the randomness of traffic load on the fatigue of elements of steel bridge structures. The phenomenon occurs specifically in the case of bridges characterized by significant width, with many traffic lanes and a high vehicle velocity, especially in the case of heavy goods vehicles. It has been shown that underestimation of operational durability, including fatigue durability, can be up to 23%. Operational loads increase due to the overlapping of traffic loads, which leads to the increased fatigue of elements of steel bridge structures. In an effort to assess this influence and its value, elements of the problem of the randomness of road traffic loads were compiled and described, and a simulative analysis of the operational strength of various lengths (spans) of the main girders of bridges was carried out. The analyses showed that for the structures with spans length of up to 10.0 m, the influence of passing vehicles could be skipped in calculations, especially in the case of weak traffic.

scholarly journals A Case Study of the Retrofitting of the Great Fish River Bridge

2018 ◽  
Vol 199 ◽  
pp. 10006
Author(s):  
Nerave Moodley ◽  
Graham Moore ◽  
David Wylie
Keyword(s):  
Economic Growth ◽  
South Africa ◽  
Eastern Cape ◽  
Traffic Loading ◽  
Economic Growth And Development ◽  
Transportation Sector ◽  
Major River ◽  
Existing Bridges ◽  
National Road

In developing countries and economies such as South Africa, retrofitting is a vital tool to maximise and extend the service life of existing infrastructure. The transportation sector plays a pivotal role in stimulating economic growth, and retrofitting existing bridges to meet the growing capacity needs of South Africa’s roads supports continued economic growth and development. This paper outlines the technical and practical challenges encountered and the solutions developed by the design team to retrofit the existing 215 m long, 9-span, Great Fish River Bridge in the Eastern Cape of South Africa. These challenges included jacking up the existing bridge under traffic loading to replace 108 existing bearings and erecting 32.5t precast beams at heights of 10.5m above a major river whilst accommodating high volumes of traffic on a busy National road.

scholarly journals Traffic load modelling and factors influencing the accuracy of predicted extremes

2005 ◽  
Vol 32 (1) ◽  
pp. 270-278 ◽  
Author(s):  
Alan O'Connor ◽  
Eugene J O'Brien
Keyword(s):  
Highway Bridges ◽  
Traffic Load ◽  
Remaining Life ◽  
Paper Briefly ◽  
Weigh In Motion ◽  
Extreme Load ◽  
Load Effects ◽  
Recorded Data ◽  
Characteristic Values ◽  
Evolution With Time

Design and assessment of highway bridges requires accurate prediction of the extreme load effects expected during the proposed or remaining life of the structure. Traditionally these effects are calculated using conservative codified deterministic loading models. While this conservatism is relatively insignificant in design, it may be critical in assessment. Advances in weigh-in-motion (WIM) technology, i.e., the process of weighing trucks travelling at full highway speeds, have increased the availability of accurate and unbiased site-specific traffic records. Assessments performed using WIM data are generally accepted as less conservative than those performed using generalized codified loading models. This paper briefly describes traffic simulation using WIM statistics. The implications of the accuracy of the recorded data and the duration of recording and of the sensitivity of the extreme to the method of prediction are investigated. Traffic evolution with time is also explored. The conclusions are of interest to engineers performing assessment of existing bridges.Key words: bridge, load effects, characteristic values, simulation, traffic flow, Monte Carlo, weigh-in-motion.

Extreme value modeling of coincident lane load effects for multi-lane factors of bridges using peaks-over-threshold method

2020 ◽  
pp. 136943322096027
Author(s):  
Junyong Zhou ◽  
Cuimin Hu ◽  
Zhixing Chen ◽  
Xiaoming Wang ◽  
Tao Wang
Keyword(s):  
Extreme Value ◽  
Traffic Load ◽  
Traffic Data ◽  
Peaks Over Threshold ◽  
Experimental Site ◽  
Short Term ◽  
Load Models ◽  
Traffic Loads ◽  
Load Effects ◽  
Value Modeling

Multi-lane factor (MLF) is a probability reduction reflecting unfavorable traffic loads over multiple lanes acting simultaneously on the most adverse position of a bridge. It is one of the key components of traffic load models for bridges. The most recent research established a multi-coefficient MLF model that clearly illustrated the lane load disparity and the probability reduction of their simultaneous actions. However, it used the block maxima (BM) method for extreme value modeling, which requires a large amount of traffic data. This study aims to adopt the peaks-over-threshold (POT) method to obtain more information from short-term traffic data and model the extreme coincident lane load effects (LLEs) for multi-coefficient MLF calibration. First, the multi-coefficient MLF model was reviewed. Thereafter, the bivariate POT method for coincident LLEs modeling using generalized Pareto distribution was proposed and formulated. Critical issues such as bivariate threshold selection and parameter estimation were addressed. Numerical examples were demonstrated to verify and validate the approach. Finally, the proposed approach was applied for calibrating the MLF of an experimental site with four traffic lanes. The results indicated that the coincident LLEs modeling using the POT approach was accurate and more effective than using the BM method when applied to limited data. The calibrated MLFs from the experimental site effectively revealed the lane load disparity of traffic loads over multiple lanes, which is not involved in the traffic load models of current bridge design specifications. Furthermore, the influence of other problems such as weight restriction on coincident LLEs modeling and MLF calibration were discussed. The proposed technique provides a sound approach for multi-coefficient MLF calibration of bridge assessment with short-term site-specific traffic data.

scholarly journals Fairness Oriented Neighbor-Channel-Aware MAC Protocol for Airborne Sensor Networks

2017 ◽  
Author(s):  
Xiaolin Gao ◽  
Jian Yan ◽  
Jianhua Lu
Keyword(s):  
Sensor Networks ◽  
Mac Protocol ◽  
Traffic Load ◽  
Media Access Control ◽  
Media Access ◽  
Traffic Loading ◽  
Protection Mechanism ◽  
Traffic Loads ◽  
The Media ◽  
Inter Frame

In airborne sensor networks (ASNs), the media access control (MAC) protocol is facing with serious unfairness problem due to the traditional protection mechanism of air-to-air communications among aircrafts. Actually by using the binary exponential back-off algorithm at high traffic loads to minimize collisions among users, the latest successful node can always benefit from this kind of MAC to obtain channel resources. Moreover, when taking the existence of the hidden nodes in ASNs into account, the inaccurate traffic load information will further aggravate the system&rsquo;s unfairness. In this paper, a neighbor-channel-aware (NCA) protocol is proposed to improve the fairness of MAC protocol in ASNs. In the proposal, the NCA frame is firstly added and exchanged between neighbor nodes periodically, which helps to resolve the inaccurate traffic load information, so as to avoid reducing the probability of successful message transmission. Then a traffic-loading based back-off algorithm is involved to make the neighbor nodes cooperatively adjust the inter-frame space (IFS) interval to further reduce the unfairness. The simulation results show that, the proposed MAC protocol can guarantee the satisfied fairness, simultaneously avoiding heavy network overloads to protect key messages&rsquo; successful transmissions in ASNs.

Highway traffic loading - AS5100 and NZTA Bridge Manual compared to international codes

2021 ◽  
Author(s):  
Steve Rhodes ◽  
Philip Icke ◽  
Paul Lyons
Keyword(s):  
Traffic Load ◽  
Highway Bridge ◽  
Highway Traffic ◽  
Bridge Design ◽  
Traffic Loading ◽  
Load Models ◽  
The Us ◽  
Load Effects ◽  
Critical Traffic

<p>Highway bridge design and assessment (rating) requires the application of notional traffic load models, with the most onerous load patterns being determined using influence surfaces. Software speeds the process of obtaining critical traffic load effects. This paper compares the requirements of – and load effects arising from – AS5100, the NZ Transport Agency Bridge Manual and other international Codes including those used in the US, UK, Canada, China, and the Eurocode.</p>

Centrifuge modeling of large-diameter underground pipes subjected to heavy traffic loads

2014 ◽  
Vol 51 (4) ◽  
pp. 353-368 ◽  
Author(s):  
Boris Rakitin ◽  
Ming Xu
Keyword(s):  
Soil Cover ◽  
Heavy Traffic ◽  
Large Diameter ◽  
Traffic Load ◽  
Initial Stresses ◽  
Centrifuge Test ◽  
Test Results ◽  
Traffic Loading ◽  
Cover Depth ◽  
Traffic Loads

Large-diameter pipes, as well as heavy vehicles, have become increasingly prevalent, which imposes uncertainties on pipe design. This paper describes the procedure and results of a series of geotechnical centrifuge tests performed on a large 1400 mm diameter reinforced concrete pipe subjected to heavy traffic loading up to 850 kN. The influence of soil cover depth, as well as the positions and magnitude of traffic loads, on the bending moments of the pipe were investigated. The centrifuge test results were found to be in reasonable agreement with those from full-scale tests. The pipe would experience the most unfavorable conditions when the heaviest axle of the traffic vehicle was located directly above the pipe crown. A deeper soil cover would lead to higher initial stresses in the pipe, as well as reduced influence of traffic load. However, even for a soil cover depth of 4 m, there is significant bending moment induced by the heavy truck loading, which cannot be ignored during pipeline design. A comparison was made between the centrifuge test results and several widely adopted design methods, and unconservative calculation results were noticed for large-diameter rigid pipes lying at a shallow soil cover depth subjected to heavy traffic loading.

scholarly journals Reliability performance of bridges designed according to TMH7 NA load model

2021 ◽  
Vol 63 (1) ◽  
Author(s):  
R Lenner ◽  
S E Basson ◽  
M Sýkora ◽  
P F Sýkora
Keyword(s):  
Highway Bridges ◽  
Traffic Load ◽  
Critical Element ◽  
Load Model ◽  
Simply Supported ◽  
Code Of Practice ◽  
First Case ◽  
Load Effects ◽  
Reliability Performance

The current code of practice for the design of highway bridges in South Africa is called Technical Methods for Highways 7 (TMH7). It was first published in 1981 and is largely based on the loading provisions of the BS5400. The purpose of this study is to carry out an investigation into the reliability performance of new highway bridges designed according to TMH7. Past studies have identified deficiencies in the traffic load model. A case study considering isolated traffic load effects and sagging moment on a simply supported bridge indicates that NA loading generally performs well for spans ranging from 15 to 50 metres. However, a poor reliability performance is seen for short-span narrow bridges, especially for 5 m and 10 m spans where the number of traffic lanes is equal to the number of notional lanes for NA loading. To study the reliability performance of a critical element, flexural behaviour of a 20 m twin-spine simply supported deck is then investigated. The results agree with the first case study. It is, however, recommended to verify the presented findings by investigation based on data from other heavy-freight routes and to account for continuous structures and shear load effects.

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