Live Load Distribution for Assessment of Highway Bridges in American and European Codes

2012 ◽  
Vol 22 (4) ◽  
pp. 574-578 ◽  
Author(s):  
Janusz Hołowaty
2018 ◽  
Vol 8 (10) ◽  
pp. 1717 ◽  
Author(s):  
Iman Mohseni ◽  
Yong Cho ◽  
Junsuk Kang

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.


Trucks were used later in various positions and strains were measured due to these truck loads. Stresses were calculated from measured strains and compared with analytical stresses calculated based on the design assumptions which are according to AASHTO Standard Specifications. Reasonable agreement between the analytical and experimental results was obtained for dead loads where the steel girders were acting alone without the concrete composite action. Furthermore the diaphragms connecting girder 5 (the instrumented girder) to girder 4 were only loosely connected under the dead loading. Differences in magnitude and distribution pattern, however, were observed for the live loading. These differences are basically due to the conservatism in AASHTO load distribution method as well as the inability of the two dimensional composite beam approach in depicting the actual three dimensional behavior of the bridge system The testing of the bridge was sponsored by Maine Department Of Transportantion, James Chandler is the Bridge Design Engineer. The analytical results presented in this paper were calculated by Steve Abbott of MODT. The interest and support of Jim and Steve as well as Karel Jacobs, also of MDOT, Is greatly appreciated. American Association of State Highway Transportation Officials, Standard Specification for Highway Bridges 2. Newmark, N., "Design of I-Beam Bridges", Transactions ASCE, Vol. 74, No. 3, Part I, March, 1948. 3. Heins, C.P. and Kuo, J.T.C., "Live Load Distribution on Simple Span Steel I-Beam Composite Highway Bridges At Ultimate Load", CE Report No. 53, University of Maryland, College Park, MD., April, 1973. 4. Heins, C.P. and Kuo, J.T.C., "Ultimate Live Load Distribution Factor For Bridges", Journal Of The Structural Division, ASCE, Vol. 101, No. ST7, Proc. Paper 11443, July 1975.

1987 ◽  
pp. 52-52

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