Impact of Specialized Hauling Vehicles and Emergency Vehicles on Bridge Load Rating

2021 ◽  
pp. 036119812110145
Author(s):  
Peng Lou ◽  
Chan Yang ◽  
Hani Nassif
Keyword(s):  
Highway Bridges ◽  
Extensive Literature ◽  
Load Rating ◽  
Motion Data ◽  
Weigh In Motion ◽  
Load Factors ◽  
Emergency Vehicles ◽  
Load Effects ◽  
Load Ratings ◽  
Bridge Load Rating

The Federal Highway Administration (FHWA) mandated states to adopt specialized hauling vehicles (SHVs) and emergency vehicles (EVs) in 2013 and 2016, respectively, in the load rating of bridges. Both the AASHTO single-unit trucks (SUs) and EVs are specially configured so that they may result in high load effects and can adversely affect bridge load rating factors. This paper investigates the impacts of rating these vehicles on the states’ bridge load ratings. An extensive literature review of the states’ load rating policies is performed. To determine whether any state can possibly be exempted from the new load ratings for SUs and EVs for Interstate highway bridges, the load effects of various state legal vehicles are analyzed and compared with those of SUs and EVs. The results of the study indicate the inevitability of executing the new load rating analysis for SUs and EVs for the vast majority of states. Weigh-in-motion data are processed to screen the potential EV traffic fleeting on the highway, and the calibrated live load factors are proposed for EVs accordingly. The load effects are found to be smaller than those FHWA originally assigned, improving the rating factors. Lastly, this paper proposes a screening tool to help state agencies to convert the known rating factors to the rating factors of SUs and EVs so that the load rating work can be prioritized for the bridges that are vulnerable to SUs and EVs.

Reliability Assessment of Steel Bridges for Specialized Hauling Vehicles

2019 ◽  
Vol 2673 (12) ◽  
pp. 391-403
Author(s):  
Peng Lou ◽  
Dongjian Gao ◽  
Hani Nassif ◽  
Mula Reddy
Keyword(s):  
Safety Margin ◽  
Steel Bridges ◽  
Live Load ◽  
Load Rating ◽  
Truck Traffic ◽  
Reliability Indices ◽  
Weigh In Motion ◽  
Load Factors ◽  
Load Effects ◽  
Existing Bridges

Specialized hauling vehicles (SHVs) are short heavy trucks within the legal weight limits but induce higher load effects than routine commercial loads. The Manual for Bridge Evaluation (MBE) adopted a series of single-unit trucks (SUs) to represent this type of vehicle. However, the SUs were introduced without rigorous reliability-based analysis due to the lack of data on SHVs. With the availability of vast amounts of data on weigh-in-motion (WIM) truck weights and configurations, the reliability of steel bridges under the SHVs should be evaluated in a more robust and quantitative manner. Through the utilization of WIM data, the authors quantified the SHVs in terms of percentages of SHVs among all truck traffic, daily average counts of SHVs, and number of axles. The gross vehicle weights (GVWs) and typical configurations of SHVs were investigated. In addition, their load effects were determined and normalized by the corresponding SUs. The maximum live loads corresponding to a return period of 5 years were also extrapolated using normal probability paper (NPP). To evaluate the effectiveness of current load-rating procedures for SHVs, the authors investigated the relationship between the load-rating factors and the corresponding reliability indices for existing bridges using the developed live load parameters based on the WIM data. Results indicated that the current live load factors were not able to provide a uniform and appropriate reliability index at different average daily truck traffic (ADTT) scenarios. This paper thus proposes new live load factors and weight adjustments of SU trucks to provide an adequate and uniform safety margin for the evaluation of steel bridges.

Diagnostic Load Testing for Bridge Load Rating

1997 ◽  
Vol 1594 (1) ◽  
pp. 125-133 ◽  
Author(s):  
Gongkang Fu ◽  
Frank P. Pezze ◽  
Sreenivas Alampalli
Keyword(s):  
Load Rating ◽  
Load Testing ◽  
Probability Of Success ◽  
Load Effects ◽  
Rating Factor ◽  
Preparation Step ◽  
Load Ratings ◽  
Reserve Strength ◽  
Diagnostic Load Testing ◽  
Bridge Load Rating

Diagnostic load testing uses field-measured data for bridge load rating without requiring certain information or the assumptions needed for analytical rating, and it can help arrive at more-reliable load ratings. It usually consists of three steps: preparation, execution, and analysis of the results. It is critical to estimate the probability of success in the preparation step before the execution step. A case of such a test for a steel highway bridge is presented. The bridge’s fascia beams were given a low rating because their cover plates were removed. Diagnostic load testing was used to obtain more reliable load ratings for the fascia beams. Under the test loads covering service loads, the support-fixity of the bridge was confirmed. It was identified as reserve strength and was not taken into account in the original analytical rating. Thus, it was concluded that no strengthening is needed for the fascia beams, and their rating factor was recommended to be increased from 0.7 to 1.4 on the basis of the measured load effects.

Probabilistic assessment of a design truck model and live load factor from weigh-in-motion data for Mexican Highway bridge design

2015 ◽  
Vol 42 (11) ◽  
pp. 970-974 ◽  
Author(s):  
A.D. García-Soto ◽  
A. Hernández-Martínez ◽  
J.G. Valdés-Vázquez
Keyword(s):  
Bridge Engineering ◽  
Load Factor ◽  
Engineering Practice ◽  
Live Load ◽  
Bridge Design ◽  
Statistical Characterization ◽  
Motion Data ◽  
Weigh In Motion ◽  
Load Factors ◽  
Truck Load

This study is focused on the statistical characterization of live load effects on bridges using weigh-in-motion data from a Mexican highway. A truck load model that is simpler than the design truck model implemented in the current Mexican requirements is suggested for design. The statistics are employed in target-reliability based calibration and verification of load factors in Mexican bridge design. Suggestions that could be useful for the Canadian bridge engineering practice are included.

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.

State-Specific LRFR Live Load Factors Using Weigh-in-Motion Data

2008 ◽  
Vol 13 (4) ◽  
pp. 339-350 ◽  
Author(s):  
Jordan Pelphrey ◽  
Christopher Higgins ◽  
Bala Sivakumar ◽  
Richard L. Groff ◽  
Bert H. Hartman ◽  
...  
Keyword(s):  
Live Load ◽  
Motion Data ◽  
Weigh In Motion ◽  
Load Factors

Probabilistic assessment of live load effects on continuous span bridges with regular and irregular configurations and its design implications

2020 ◽  
Vol 47 (4) ◽  
pp. 405-417
Author(s):  
A.D. García-Soto ◽  
A. Hernández-Martínez ◽  
J.G. Valdés-Vázquez
Keyword(s):  
Probabilistic Assessment ◽  
Live Load ◽  
Load Model ◽  
Motion Data ◽  
Load Models ◽  
Weigh In Motion ◽  
Single Vehicle ◽  
Load Effects ◽  
Extreme Distribution ◽  
Live Load Model

Studies on live load effects reported in recent literature are based on simple span bridges or on a limited number of continuous span bridges and regular configurations. In this study, an extensive probabilistic assessment of live load effects on continuous bridges is carried out for regular and irregular span configurations using weigh-in-motion data. Single vehicle passage is considered, and live load effects are compared with those from a live load model developed for simple spans from the same database. Truck models from Canada are also used for comparison purposes. Discussion of the fitting of extreme distribution is included, and an optimization scheme for the fitting is proposed. The most important finding of the study is that the use of live load models developed from simple spans or a limited number of continuous spans may not be suitable for designing continuous bridges, especially those with irregular configurations and short spans.

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