Reliability analysis of typical highway bridges in Manitoba designed to the Modified HSS-25 live load model

2021 ◽  
Author(s):  
Amanda Pushka ◽  
Jonathan D Regehr ◽  
Graziano Fiorillo ◽  
Aftab Mufti ◽  
Basheer Hasan Algohi
Keyword(s):  
Reliability Analysis ◽  
Prestressed Concrete ◽  
Highway Bridges ◽  
Live Load ◽  
Load Model ◽  
Reliability Indices ◽  
Structural Capacity ◽  
Live Load Model ◽  
Aashto Lrfd ◽  
Precast Prestressed Concrete

Several provinces in Canada have modified the live load model specified in national bridge design codes to account for locally permitted trucks. Manitoba similarly introduced a live load model for the design of provincial bridges in accordance with AASHTO LRFD, the Modified HSS-25. This article presents truck weight datasets and methods used to develop Manitoba-specific live load statistics to conduct a reliability analysis for three typical simply supported structure types: precast prestressed concrete box girder, precast prestressed concrete I-girder and steel girder. The average reliability indices ranged from 4.69 to 4.95 with respect to the AASHTO LRFD live load statistics used to calibrate the code and 4.65 to 5.04 with respect to the Manitoba statistics. The results demonstrate a level of safety that exceeds the code requirements, indicating that structures designed to the HSS-25 potentially possess the structural capacity to withstand increased vehicular load effects for the considered bridge types.

Calibration of the Ontario Highway Bridge Design Code 1991 edition

1994 ◽  
Vol 21 (1) ◽  
pp. 25-35 ◽  
Author(s):  
Andrzej S. Nowak ◽  
Hid N. Grouni
Keyword(s):  
Reinforced Concrete ◽  
Reliability Analysis ◽  
Prestressed Concrete ◽  
Highway Bridge ◽  
Live Load ◽  
Design Code ◽  
Reliability Indices ◽  
Resistance Factors ◽  
Load And Resistance Factors ◽  
Selection Of

The paper describes the calculation of load and resistance factors for the Ontario Highway Bridge Design Code (OHBDC) 1991 edition. The work involved the development of load and resistance models, the selection of the reliability analysis method, and the calculation of the reliability indices. The statistical models for load and resistance are reviewed. The considered load components include dead load, live load, and dynamic load. Resistance models are developed for girder bridges (steel, reinforced concrete, and prestressed concrete). A reliability analysis is performed for selected representative structures. Reliability indices are calculated using an iterative procedure. The calculations are performed for bridge girders designed using OHBDC 1983 edition. The resulting reliability indices are between 3 and 4 for steel girders and reinforced concrete T-beams, and between 3.5 and 5 for prestressed concrete girders. Lower values are observed for shorter spans (up to 30–40 m). The acceptance criterion in the selection of load and resistance factors is closeness to the target reliability level. The analysis confirmed the need to increase the design live load for shorter spans. Partial resistance factors are considered for steel and concrete. The criteria for the evaluation of existing bridges are based on the reliability analysis and economic considerations. Key words: bridge code, calibration, load factor, resistance factor, reliability index.

scholarly journals Live load model for highway bridges

1993 ◽  
Vol 13 (1-2) ◽  
pp. 53-66 ◽  
Author(s):  
Andrzej S. Nowak
Keyword(s):  
Highway Bridges ◽  
Live Load ◽  
Load Model ◽  
Live Load Model

scholarly journals Development of Brazilian highway live load model for unlimited fatigue life

2020 ◽  
Vol 13 (4) ◽  
Author(s):  
Anselmo Leal Carneiro ◽  
Enson de Lima Portela ◽  
Túlio Nogueira Bittencourt
Keyword(s):  
Fatigue Life ◽  
Bending Moment ◽  
Highway Bridges ◽  
Live Load ◽  
Box Girders ◽  
Load Effect ◽  
Load Model ◽  
Weigh In Motion ◽  
Bias Factor ◽  
Live Load Model

Abstract This work studies the fatigue live load model used in Brazil for highway bridges. Using the unlimited fatigue life approach, the current live load model is evaluated in relation to the actual traffic and a new fatigue live load model is proposed. Weigh-in-motion (WIM) stations data on two important Brazilian highways are used. The main structural analysis performed in this paper consider the bridges as box girders or multiple girders. The ratio between real traffic and the live load model load effect (bias factor) are determined for single and continuous spans in terms of bending moment and shear force. It is found that the bias factor of the current live load can vary a lot and may not ensure unlimited fatigue life. The proposed model, on the other hand, presents more uniform bias factors and is in accordance with the unlimited fatigue life approach for the WIM data.

Development of Live Load Model for Strength II Limit State in AASHTO LRFD Design Specifications

2018 ◽  
Vol 2672 (41) ◽  
pp. 11-23
Author(s):  
Peng Lou ◽  
Hani Nassif ◽  
Paul Truban
Keyword(s):  
New Jersey ◽  
Limit State ◽  
Extreme Value Distribution ◽  
Generalized Extreme Value Distribution ◽  
Load Factor ◽  
Live Load ◽  
Load Model ◽  
Design Specifications ◽  
Live Load Model ◽  
Aashto Lrfd

The AASHTO LRFD Bridge Design Specifications defines Strength II limit state for agencies to consider the load combination by owner-specified special design vehicles, evaluation permit vehicles, or both. The configuration and characteristics of permit vehicles vary from state to state. In addition, the code calibration process performed in 1994 for the development of the live load factors was applied only to the Strength I limit state. In New Jersey, the design permit vehicle was not developed based on actual permit records or weigh-in-motion (WIM) data. Recently, with the development of permit-issuing management and WIM technology, there is a need to evaluate the effectiveness of design permit vehicles. This study aims to develop a live load model for the assessment of Strength II limit state for New Jersey Department of Transportation (NJDOT). Five years of permit vehicle records are provided by NJDOT for the development of the live load model. The distribution of Gross Vehicle Weight is best described as the Generalized Extreme Value distribution. Load effects are simulated for different span lengths. The mean and standard deviation (SD) of the 75-year maximum loads are predicted using different extrapolation approaches. The results show that NJDOT Design Permit Vehicle provides stable mean and SD of bias ratios at 75-year level. In comparison with the current AASHTO live load factor of 1.35, the averages of the bias ratios at the 75-year level are found to be 1.31, 1.23, and 1.16 for the positive moment, shear, and negative moment, respectively.

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.

Reliability Analysis of Prestressed Concrete Bridges in Mexico: Assessment and Live Load Factors Proposal

2021 ◽  
Author(s):  
Rolando Salgado-Estrada ◽  
Sergio A. Zamora-Castro ◽  
Agustín L. Herrera-May ◽  
Yessica A. Sánchez-Moreno ◽  
Yair S. Sánchez-Moreno
Keyword(s):  
Reliability Analysis ◽  
Prestressed Concrete ◽  
Concrete Bridges ◽  
Live Load ◽  
Prestressed Concrete Bridges ◽  
Load Factors

Safe Platooning Headways on Girder Bridges

2021 ◽  
pp. 036119812110363
Author(s):  
Bowen Yang ◽  
Joshua S. Steelman ◽  
Jay A. Puckett ◽  
Daniel G. Linzell
Keyword(s):  
Prestressed Concrete ◽  
Limit State ◽  
Live Load ◽  
Load Effect ◽  
Operational Strategies ◽  
Reliability Indices ◽  
Girder Bridges ◽  
Legal Limits ◽  
Weigh In Motion ◽  
Load And Resistance Factor

Truck platooning—digitally linking two or more trucks to travel in a closely spaced convoy—is an emerging technology with the potential to save fuel and reduce labor. A framework is described to determine how much a platoon permit load might be increased above Federal Bridge Formula B legal limits, given strict control over the load characteristics and operational tactics. Soon, platoons are expected to advance not only with respect to traffic operations but also in their ability to weigh and report axle weight and spacing, functioning as mobile weigh-in-motion vehicles. Consequently, platoon live load statistics (bias and coefficient of variation) can differ from code assumptions, and are perhaps controllable, which poses a significant opportunity with respect to operational strategies. A parametric study is presented that examined safe headways between platooning trucks, considering different girder spacings, span lengths, numbers of spans, types of structure, truck configurations, numbers of trucks, and adjacent lane loading scenarios. The Strength I limit state was evaluated for steel and prestressed concrete I-girder bridges optimally designed using load and resistance factor design. Reliability indices, β, were calculated for each load case based on Monte Carlo simulation. Summary headway guidance was developed and is presented here to illustrate potential safe operational strategies for varying truck weights and platoon live load effect uncertainties.

Sign in / Sign up

Export Citation Format

Share Document