Investigation of the Applicability of AASHTO LRFD Live Load Distribution Equations for Integral Bridge Substructures

2009 ◽  
Vol 12 (4) ◽  
pp. 559-578 ◽  
Author(s):  
Semih Erhan ◽  
Murat Dicleli
Keyword(s):  
Load Distribution ◽  
Structural Models ◽  
Slab Thickness ◽  
Live Load ◽  
Span Length ◽  
Integral Bridge ◽  
Live Load Distribution ◽  
Load Distribution Factors ◽  
Aashto Lrfd ◽  
Bridge Substructures

In this study, applicability of the AASHTO LRFD girder live load distribution equations (LLDEs) for integral bridge (IB) abutments and piles is investigated. For this purpose, numerous 3-D and corresponding 2-D structural models of typical IBs are built and analyzed under AASHTO LRFD live load. In the analyses, the effect of various superstructure properties such as span length, slab thickness, girder spacing and stiffness are considered. The results from the 2-D and 3-D analyses are then used to calculate the live load distribution factors (LLDFs) for the abutments and piles of IBs as a function of the above mentioned properties. The analyses results revealed that using AASHTO LRFD LLDEs result in generally unconservative estimates of live load moment in the abutments. However, AASHTO LRFD LLDEs are found to produce exceedingly conservative estimates of live load shear in the abutments as well as live load shear and moment in the piles.

Analysis on Live Load Distribution Factors of Widened Hollow Core Slab Bridges

2019 ◽  
Vol 953 ◽  
pp. 215-222
Author(s):  
Li Fang Zhang ◽  
Ying Wang ◽  
Ying Ge Lei ◽  
Yun Chang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Load Distribution ◽  
Live Load ◽  
Span Length ◽  
Hollow Core ◽  
Skew Angle ◽  
Hollow Core Slab ◽  
Live Load Distribution ◽  
Load Distribution Factors

There are some studies on live load distribution factors(LLDF) of hollow core slab bridges which mainly consider the influence of connecting method and rigidity, while the effects of span length and skew angle have not been fully involved. Influenced by the trend of road and river, the hollow core slab bridges are often skewed with rivers. So it is essential to study the span length and skew angle effects in bridge widening. Based on a highway widening project, some representative hollow core slab bridges are selected for widening analysis. Theoretical method and finite element method are used to analysis the LLDF of slab bridges before and after widening. Finite element method(FEM) can give high precision in LLDF calculating. The influences of span length, connecting stiffness and skew angle are studied. The result indicates that no matter before or after widening the LLDF become smaller with the increase of span length. After widening, the LLDF of the half slabs near to the widening seam reduce obviously and with the span length increases the variation becomes more obviously. The connecting stiffness brings small influence to the LLDF in hollow core slab bridges. And with the increase of skew angle, the LLDF of the new side slab changes obviously, but the variation of LLDF of original slabs is not obviously according to skew angle.

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.

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