Evolution of Bridge Live Load Models and Truck Weight Limits:The Case of Manitoba, Canada

2021 ◽  
Author(s):  
Amanda Pushka ◽  
Jonathan D Regehr ◽  
Aftab Mufti ◽  
Basheer Hasan Algohi ◽  
Graziano Fiorillo
Keyword(s):  
Operational Performance ◽  
Potential Range ◽  
Live Load ◽  
Design Codes ◽  
Bridge Design ◽  
Evaluation Codes ◽  
Load Models ◽  
Truck Size And Weight ◽  
Truck Weight ◽  
Regulation Changes

Truck size and weight regulations have been a key instrument used to improve trucking productivity, safety, and operational performance in Canada. In response to these changes, bridge design codes undergo modifications to envelop the potential range of trucks in operation. A five-decade timeline is presented: (1) to document how bridge codes and their live load models have evolved, with a focus on the Manitoba-specific HSS-25 truck, and (2) to discuss how responsive bridge design codes have historically been to changes in truck size and weight regulations. While at times bridge codes are released in conjunction with expected regulation changes, there is often delay in the issuance of revised bridge design and evaluation codes. Assessments of the current truck fleet, which now includes long combination vehicles (LCVs), may be a consideration for future bridge design live load models.

Load Combinations for the Evaluation of Redundancy in Steel Bridges

2022 ◽  
pp. 036119812110621
Author(s):  
Francisco Javier Bonachera Martin ◽  
Robert J. Connor
Keyword(s):  
Bridge Engineering ◽  
Live Load ◽  
Steel Bridge ◽  
Bridge Design ◽  
Load Model ◽  
Load Models ◽  
Evaluation Procedures ◽  
Tension Member ◽  
Service Period ◽  
Aashto Lrfd

Over the past decade, there has been considerable interest in the development of quantitative analytical procedures to determine if a primary steel tension member (PSTM) is a fracture critical member (FCM). Traditionally, this designation has most often been arbitrarily determined based simply on the bridge geometry, for example, the number of girders in the cross section, rather than an evaluation of the bridge in the faulted state. Clearly, such a redundancy evaluation must address the loading scenarios concurrent with failure of the PSTM, the likelihood of the member failure, the acceptable probability of load exceeding resistance in the faulted state, and the application of vehicular live load models. This research was conducted to develop a load model and load combinations that are specific to evaluating the performance of a bridge in the event a steel member was to fracture. Specifically, two load combinations were developed to evaluate the strength of a steel bridge, one for the event in which the failure of a PSTM occurs, and another for a post-failure service period. The development adhered to the reliability-based principles and procedures applied in the calculation of load combinations currently used in bridge engineering to facilitate direct implementation and to ensure consistency with current steel bridge design and evaluation procedures contained in the AASHTO LRFD Bridge Design Specifications.

scholarly journals Investigation of the Adequacy of Bridge Design Loads in Pakistan

2019 ◽  
Vol 4 (2) ◽  
pp. 171-187
Author(s):  
I Shahid ◽  
A. K. Noman ◽  
S. H. Farooq ◽  
Ali Arshad
Keyword(s):  
Reliability Index ◽  
Structural Reliability ◽  
Highway Bridges ◽  
Developed Countries ◽  
Live Load ◽  
Bridge Design ◽  
Safety Level ◽  
Reliability Indices ◽  
Load Models ◽  
Design Case

Weight, configuration, and volume of traffic vary from country to country. But, in developing countries like Pakistan, bridges are designed based on codes of developed countries. Hence, these bridges may not have desired safety level. In this study, safety levels of three sample bridges has been investigated in terms of structural reliability index.  Live load effects (shear and moments) in girders were determined using weigh-in-motion data (WIM) and were extrapolated to 75 years using non-parametric fit. Two live load models and two strengths, required by 1967 Pakistan Code of Practice for Highway Bridges (PHB Design-Case) and that required by the 2012 AASHTO LRFD Bridge Design Specifications (AASHTO Design-Case) were used in reliability analysis. It is found that actual trucks produce moment and shear in girders 11 to 45 percent higher than live load models of PHB and AASHTO design cases. Values of structural reliability indices vary from 1.25 to 2.50 and from 2.45 to 3.15 for PHB and AASHTO design cases, respectively, and are less than the target reliability index value of 3.50 used in the design codes as benchmark.  It is revealed after the research that bridges in Pakistan may not have desired safety level, and current live load models may not be the true representation of service-level truck traffic.

Bridge Live Load Models in U.S. and Europe

2018 ◽  
pp. 1434-1441
Author(s):  
Anjan Ramesh Babu ◽  
Andrzej S. Nowak ◽  
Eugene J. O’Brien
Keyword(s):  
Live Load ◽  
Load Models

Live-Load Response of Alabama’s High-Performance Concrete Bridge

2003 ◽  
Vol 1845 (1) ◽  
pp. 115-124 ◽  
Author(s):  
Robert W. Barnes ◽  
J. Michael Stallings ◽  
Paul W. Porter
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Highway Bridges ◽  
Live Load ◽  
Bottom Flange ◽  
Actual Behavior ◽  
Bridge Design ◽  
Design Specifications ◽  
Special Procedure ◽  
Aashto Lrfd

Results are reported from live-load tests performed on Alabama’s high-performance concrete (HPC) showcase bridge. Load distribution factors, deflections, and stresses measured during the tests are compared with values calculated using the provisions of the AASHTO LRFD Bridge Design Specifications and AASHTO Standard Specifications for Highway Bridges. Measured dynamic amplification of load effects was approximately equal to or less than predicted by both specifications. Distribution factors from both specifications were found to be conservative. Deflections computed according to AASHTO LRFD Bridge Design Specifications suggestions matched best with the measured deflections — overestimating the maximum deflections by 20% or less. Bottom flange stresses computed with AASHTO distribution factors were significantly larger than measured values. AASHTO LRFD Bridge Design Specifications provisions suggest a special procedure for computing exterior girder distribution factors in bridges with diaphragms. When two or more lanes were loaded, this special procedure did not reflect the actual behavior of the bridge and resulted in very conservative distribution factors for exterior girders. Further research is recommended to correct this deficiency.

Statistics of Extremes: An Alternate Method with Application to Bridge Design Codes

Technometrics ◽  
1979 ◽  
Vol 21 (2) ◽  
pp. 185-191 ◽  
Author(s):  
James V. Zidek ◽  
Francis P.D. Navin ◽  
Richard Lockhart
Keyword(s):  
Design Codes ◽  
Bridge Design ◽  
Statistics Of Extremes

Bridge live load models from WIM data

2002 ◽  
Vol 24 (8) ◽  
pp. 1071-1084 ◽  
Author(s):  
T.J. Miao ◽  
T.H.T. Chan
Keyword(s):  
Live Load ◽  
Load Models
Sign in / Sign up

Export Citation Format

Share Document