scholarly journals Methodology for development of live load models for refined analysis of short and medium-span highway bridges

2017 ◽  
Vol 14 (4) ◽  
pp. 477-490 ◽  
Author(s):  
Giorgio Anitori ◽  
Joan R. Casas ◽  
Michel Ghosn
Keyword(s):  
Highway Bridges ◽  
Live Load ◽  
Load Models

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 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.

WIM-Based Live Load Models for Highway Bridges

2012 ◽  
Vol 18 (33) ◽  
pp. 68-75
Author(s):  
Andrzej S. Nowak ◽  
Przemyslaw Rakoczy
Keyword(s):  
Highway Bridges ◽  
Live Load ◽  
Load Models

scholarly journals Live Load Distribution Factors for Skew Stringer Bridges with High-Performance-Steel Girders under Truck Loads

2018 ◽  
Vol 8 (10) ◽  
pp. 1717 ◽  
Author(s):  
Iman Mohseni ◽  
Yong Cho ◽  
Junsuk Kang
Keyword(s):  
Load Distribution ◽  
Shear Force ◽  
High Performance ◽  
Structural Parameters ◽  
Highway Bridges ◽  
Live Load ◽  
High Performance Steel ◽  
Live Load Distribution Factors ◽  
Live Load Distribution ◽  
Load Distribution Factors

Because the methods used to compute the live load distribution for moment and shear force in modern highway bridges subjected to vehicle loading are generally constrained by their range of applicability, refined analysis methods are necessary when this range is exceeded or new materials are used. This study developed a simplified method to calculate the live load distribution factors for skewed composite slab-on-girder bridges with high-performance-steel (HPS) girders whose parameters exceed the range of applicability defined by the American Association of State Highway and Transportation Officials (AASHTO)’s Load and Resistance Factor Design (LRFD) specifications. Bridge databases containing information on actual bridges and prototype bridges constructed from three different types of steel and structural parameters that exceeded the range of applicability were developed and the bridge modeling verified using results reported for field tests of actual bridges. The resulting simplified equations for the live load distribution factors of shear force and bending moment were based on a rigorous statistical analysis of the data. The proposed equations provided comparable results to those obtained using finite element analysis, giving bridge engineers greater flexibility when designing bridges with structural parameters that are outside the range of applicability defined by AASHTO in terms of span length, skewness, and bridge width.

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

Modeling maximum live load effects on highway bridges

2008 ◽  
pp. 335-341 ◽  
Author(s):  
Bala Sivakumar ◽  
Fred Moses ◽  
Michel Ghosn
Keyword(s):  
Highway Bridges ◽  
Live Load ◽  
Load Effects

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.

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