Simplified Live Load Distribution Factor Equation for Steel Girder Bridges

The live load distribution factor equations provided by AASHTO load and resistance factor design specifications for the decked precast, prestressed concrete (DPPC) girder bridge system do not differentiate between a single-lane or a multilane loaded condition. This practice results in a single-lane load rating penalty for DPPC girder bridges. This paper determines distribution factor equations that accurately predict the distribution factor of the DPPC girder bridge system when it is subjected only to single-lane loading. Eight DPPC girder bridges were instrumented. Each bridge was loaded with a single load vehicle to simulate the single-lane loaded condition. The experimental data were used to calibrate grillage models of the DPPC girder bridge system. The calibrated grillage models were used to conduct a parametric study of the DPPC girder bridge system subjected to a single-lane loaded condition. Four new equations that describe the single-lane loaded distribution factor for both shear and moment forces of these bridges are developed in this paper.

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Verification of shear live-load distribution factor equations for I-girder bridges

KSCE Journal of Civil Engineering ◽

10.1007/s12205-013-0607-3 ◽

2013 ◽

Vol 17 (3) ◽

pp. 550-555 ◽

Cited By ~ 6

Author(s):

Nakin Suksawang ◽

Hani Nassif ◽

Dan Su

Keyword(s):

Load Distribution ◽

Live Load ◽

Distribution Factor ◽

Girder Bridges ◽

Live Load Distribution ◽

Load Distribution Factor

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INFLUENCE OF SPAN LENGTH AND CROSSBEAM ON LOAD DISTRIBUTION FACTOR FOR GIRDER BRIDGES

Proceedings of International Structural Engineering and Construction ◽

10.14455/isec.res.2016.20 ◽

2016 ◽

Vol 3 (1) ◽

Author(s):

Hyo-Gyoung Kwak ◽

Joungrae Kim

Keyword(s):

Finite Element ◽

Load Distribution ◽

Span Length ◽

Distribution Factor ◽

Steel Girder ◽

Girder Bridges ◽

Load Distribution Factor ◽

Exterior Girder ◽

Grillage Method ◽

Concrete Girder

Load distribution factor at concrete girder bridges and steel girder bridges are analyzed with finite element method to see effect of span length and cross beam to load distribution factor. Span lengths of analyzed bridge models are 30m, 40m, 50m and 60m. The number of intermediate cross beam is increased from one to until distance between cross beams becomes 5m. The finite element analysis results show that concrete girder and steel girder can use same load distribution factor and span length doesn’t affect to load distribution factor. Even though load distribution factor in interior girders is not influenced by cross beam, in exterior girders it is influenced by cross beam. Effect of cross beam in exterior girder is influenced by the number of lanes and distance from exterior girder to curb. Since design code introduces conservative load distribution factor, economically improved load distribution factor is proposed. The proposed load distribution factor includes cross beam effect with the number of lanes and distance from exterior girder to curb. The proposed equation is compared with AASHTO code and grillage method which is well-known method to calculate load distribution. The comparison results showed that the proposed equation is more efficient and useful than AASHTO and safer than the grillage method.

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Live Load Distribution in Prestressed Concrete Girder Bridges with Curved Slab

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.284-287.1441 ◽

2013 ◽

Vol 284-287 ◽

pp. 1441-1445

Author(s):

Doo Yong Cho ◽

Sun Kyu Park ◽

Woo Seok Kim

Keyword(s):

Finite Element ◽

Prestressed Concrete ◽

Parametric Study ◽

Load Distribution ◽

Critical Parameters ◽

Live Load ◽

Finite Element Analyses ◽

Distribution Factor ◽

Girder Bridges ◽

Live Load Distribution

This paper presents the live load distribution in straight prestressed concrete (PSC) girder bridges with curved deck slab utilizing finite element analyses. Numerical modeling methodology was established and calibrated based on field testing results. A parametric study of 73 cases with varying 6 critical parameters was used to determine a trend over each parameter. Through live load girder distribution factor (GDF) comparisons between the AASHTO LRFD, AASHTO Standard factors and finite element analyses results, both AASHTO live load distribution predicted conservatively in most bridges considered in the parametric study. However, in the bridges with curved slab, GDF was underestimated due to curvature influences. This study proposes a new live load distribution formula to predict rational and conservative live load distribution in PSC girder bridges with curved slab for a preliminary design purpose. The proposed live load distribution provides better live load analysis for the PSC girder bridge with curved slab and ensures the GDF is not underestimated.

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