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.

Research on the general method for extrapolating traffic load effects for highway bridges

Stahlbau ◽  
2014 ◽  
Vol 83 (3) ◽  
pp. 186-198 ◽  
Author(s):  
Weizhen Chen ◽  
Zhenlin Xie ◽  
Bochong Yan
Keyword(s):  
Highway Bridges ◽  
Traffic Load ◽  
Load Effects ◽  
General Method

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>

Development of a traffic load model for bridge structures within an urban subway system

2021 ◽  
Author(s):  
Thibault Tepho ◽  
Marcel Nowak ◽  
Oliver Fischer ◽  
Philipp Tamm ◽  
Markus Schöning
Keyword(s):  
Scaling Factor ◽  
Traffic Load ◽  
Load Model ◽  
Extreme Load ◽  
Bridge Structures ◽  
Subway System ◽  
Engineering Standards ◽  
Load Effects ◽  
Factor Α

<p>Subway systems are a key component of today’s urban infrastructure. However, current engineering standards such as the Eurocode only give few indications regarding the modelling of traffic loads for subway trains. For this reason, a traffic load model is developed based on load model LM71 from Eurocode 1 - Part 2, the standard load model for rail bridges. The aim is to scale this load model so that it is able to cover the extreme load effects resulting from actual subway trains within the subway network. Within the scope of these investigations, different structural systems and load effects are studied, as well as different strategies for modifying LM71 and its scaling factor α. Additionally, the results obtained for simplified beam systems are validated on real structures to account for effects like two-dimensional bearing capacity for the determination of the scaling factor α. These investigations are performed for the subway system of the city of Munich.</p>

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.

scholarly journals Towards actual brazilian traffic load models for short span highway bridges

2015 ◽  
Vol 8 (2) ◽  
pp. 124-139 ◽  
Author(s):  
C. E. Rossigali ◽  
M. S. Pfeil ◽  
R. C. Battista ◽  
L. V. Sagrilo
Keyword(s):  
Highway Bridges ◽  
Traffic Load ◽  
Live Load ◽  
Heavy Vehicles ◽  
Load Model ◽  
Load Models ◽  
Short Span ◽  
Live Load Model ◽  
Traffic Simulations ◽  
Gathering Data

New live load models for highway bridge design in Brazil are under development by assembling real traffic database, traffic simulations, analytical-numerical modeling of the dynamic interaction between vehicle and structure and statistical extrapolations. This paper presents and discusses the results obtained in the first stages of this work which includes the comparison between the static effects due to the actual traffic of heavy vehicles and those generated by the live load model given in the current national code NBR 7188. It is demonstrated that this live load model is not appropriate to represent the actual traffic effects and may be, in some cases, non-conservative. The present work deals with short span bridges for two lanes single carriageway under free flow traffic scenarios. The representative static effects in these bridges due to the actual traffic of heavy vehicles are obtained by extrapolating its probability density functions to a certain return period. To this purpose, a traffic database was constructed by gathering data from several weighing stations in Brazilian highways which was then applied to perform traffic simulations through a specially developed computational tool.

scholarly journals Evaluation of a current vehicle load model using weigh-in-motion records: a case in China

2016 ◽  
Vol 11 (3) ◽  
pp. 197-204
Author(s):  
Zigang Xu ◽  
Qiang Han ◽  
Junfeng Jia ◽  
Zilan Zhong ◽  
Chao Huang
Keyword(s):  
Traffic Flow ◽  
Highway Bridges ◽  
Live Load ◽  
Flow Conditions ◽  
Load Model ◽  
Vehicle Load ◽  
Weigh In Motion ◽  
National Highway ◽  
Load Effects ◽  
Existing Bridges

In order to assess the vehicle load carrying capacity of existing bridges on the national highway G103 in Beijing, the vehicle load model for the practical traffic flow conditions needs to be determined. Based on the traffic axle load data measured by the weigh-in-motion system and the methods proposed by General Code for Design of Highway Bridges and Culverts (JTG D60-2004) and Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts (JTG D62-2004), the vehicle load parameters under practical traffic flow conditions are investigated. A typical 6-axle vehicle model with a 2-1-3 axial pattern is proposed by using the statistical analysis of total weight, axial weight, etc. The live load effects of Daliushu No. 2 Bridge, one highway bridge on the national highway G103, are analyzed using the proposed model and compared to the vehicle load model given in the Chinese code. The results show that there are great differences in the vehicle load parameters and the live load effects from the proposed vehicle load model increased by 20–50% compared with the model given by the code. The overweight vehicles are potential threats to the safety of existing bridges.

Scales and Units

2018 ◽  
Author(s):  
Kathryn M. de Luna
Keyword(s):  
Language Change ◽  
Historical Linguistics ◽  
Bantu Languages ◽  
The North ◽  
First Case ◽  
Linguistic Evidence ◽  
River Region ◽  
History Of ◽  
Alternative Approaches

This chapter uses two case studies to explore how historians study language movement and change through comparative historical linguistics. The first case study stands as a short chapter in the larger history of the expansion of Bantu languages across eastern, central, and southern Africa. It focuses on the expansion of proto-Kafue, ca. 950–1250, from a linguistic homeland in the middle Kafue River region to lands beyond the Lukanga swamps to the north and the Zambezi River to the south. This expansion was made possible by a dramatic reconfiguration of ties of kinship. The second case study explores linguistic evidence for ridicule along the Lozi-Botatwe frontier in the mid- to late 19th century. Significantly, the units and scales of language movement and change in precolonial periods rendered visible through comparative historical linguistics bring to our attention alternative approaches to language change and movement in contemporary Africa.

Applications of random graphs

2017 ◽  
Author(s):  
A.C.C. Coolen ◽  
A. Annibale ◽  
E.S. Roberts
Keyword(s):  
Social Networks ◽  
Random Graphs ◽  
Interaction Network ◽  
Power Grids ◽  
Protein Protein Interaction ◽  
Topological Features ◽  
First Case ◽  
The Stability ◽  
Protein Protein Interaction Network

This chapter reviews graph generation techniques in the context of applications. The first case study is power grids, where proposed strategies to prevent blackouts have been tested on tailored random graphs. The second case study is in social networks. Applications of random graphs to social networks are extremely wide ranging – the particular aspect looked at here is modelling the spread of disease on a social network – and how a particular construction based on projecting from a bipartite graph successfully captures some of the clustering observed in real social networks. The third case study is on null models of food webs, discussing the specific constraints relevant to this application, and the topological features which may contribute to the stability of an ecosystem. The final case study is taken from molecular biology, discussing the importance of unbiased graph sampling when considering if motifs are over-represented in a protein–protein interaction network.

Investigating the potential of redundant manipulators in narrow channels

2020 ◽  
pp. 095440622096451
Author(s):  
Ashish Singla ◽  
Jyotindra Narayan ◽  
Himanshu Arora
Keyword(s):  
Case Studies ◽  
Fuzzy Inference ◽  
Redundant Manipulators ◽  
Redundancy Resolution ◽  
Inference System ◽  
Narrow Channels ◽  
First Case ◽  
Task Priority ◽  
Patient Side

In this paper, an attempt has been made to investigate the potential of redundant manipulators, while tracking trajectories in narrow channels. The behavior of redundant manipulators is important in many challenging applications like under-water welding in narrow tanks, checking the blockage in sewerage pipes, performing a laparoscopy operation etc. To demonstrate this snake-like behavior, redundancy resolution scheme is utilized using two different approaches. The first approach is based on the concept of task priority, where a given task is split and prioritize into several subtasks like singularity avoidance, obstacle avoidance, torque minimization, and position preference over orientation etc. The second approach is based on Adaptive Neuro Fuzzy Inference System (ANFIS), where the training is provided through given datasets and the results are back-propagated using augmentation of neural networks with fuzzy logics. Three case studies are considered in this work to demonstrate the redundancy resolution of serial manipulators. The first case study of 3-link manipulator is attempted with both the approaches, where the objective is to track the desired trajectory while avoiding multiple obstacles. The second case study of 7-link manipulator, tracking trajectory in a narrow channel, is investigated using the concept of task priority. The realistic application of minimum-invasive surgery (MIS) based trajectory tracking is considered as the third case study, which is attempted using ANFIS approach. The 5-link spatial redundant manipulator, also known as a patient-side manipulator being developed at CSIR-CSIO, Chandigarh is used to track the desired surgical cuts. Through the three case studies, it is well demonstrated that both the approaches are giving satisfactory results.

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