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 Structural Design Issues For Integral Abutment Bridges

2021 ◽  
Author(s):  
Navid Nikravan
Keyword(s):  
Finite Element ◽  
Load Distribution ◽  
Finite Element Models ◽  
Live Load ◽  
Skew Angle ◽  
Temperature Variations ◽  
Integral Bridges ◽  
Live Load Distribution Factors ◽  
Live Load Distribution ◽  
Load Distribution Factors

In recent years, integral abutment bridges have been increasingly used in Canada due to their low maintenance costs. Whereas a rational guideline to determine the maximum length and skew angle limits for integral bridges due to temperature variations do not exist in bridge codes. As such, structural behavior of integral bridges subjected to temperature variation was investigated through a numerical modeling. First, detailed 3D finite-element models were developed. The accuracy of finite-element models was validated against data collected from filed testing available in the literature on integral bridges subjected to the seasonal temperature variations and truck loading. Then, a parametric study was carried out to study the effects of key parameters on the performance of integral bridges when subjected to temperature variations. The numerical results indicated that number of design lanes, bridge length, abutment height, abutment-pile connection, pile size and skew angle had a significant impact on the behavior of integral bridges. Based on the data generated from the parametric study, new limits for the maximum length and skew angle of integral bridges based on displacement-ductility limit state of piles were established. Literature review revealed that live load distribution among girders in integral bridges due to truck loading conditions is as yet unavailable. This study is extended to develop new equations to estimate girder live load distribution factors for integral bridges. First, 2D and 3D finite-element models (FEMs) of integral bridges were developed. Then, a parametric study was performed to study the effects of parameters such as abutment height, abutment thickness, wingwall length, wingwall orientation, number of design lanes, span length, girder spacing and number of intermediate diaphragms. The results indicated that the live load distribution factors obtained from the FEMs were lower than those obtained from current CHBDC equations. Consequently, sets of empirical expressions were developed in the form of reduction factors that can be applied to CHBDC live load distribution factors to accurately calculate the girder distribution factors. Also, other set of equations for the live load distribution factors were developed in a similar form as that specified in CHBDC for possible inclusion in the bridge code.

scholarly journals Structural Design Issues For Integral Abutment Bridges

2021 ◽  
Author(s):  
Navid Nikravan
Keyword(s):  
Finite Element ◽  
Load Distribution ◽  
Finite Element Models ◽  
Live Load ◽  
Skew Angle ◽  
Temperature Variations ◽  
Integral Bridges ◽  
Live Load Distribution Factors ◽  
Live Load Distribution ◽  
Load Distribution Factors

In recent years, integral abutment bridges have been increasingly used in Canada due to their low maintenance costs. Whereas a rational guideline to determine the maximum length and skew angle limits for integral bridges due to temperature variations do not exist in bridge codes. As such, structural behavior of integral bridges subjected to temperature variation was investigated through a numerical modeling. First, detailed 3D finite-element models were developed. The accuracy of finite-element models was validated against data collected from filed testing available in the literature on integral bridges subjected to the seasonal temperature variations and truck loading. Then, a parametric study was carried out to study the effects of key parameters on the performance of integral bridges when subjected to temperature variations. The numerical results indicated that number of design lanes, bridge length, abutment height, abutment-pile connection, pile size and skew angle had a significant impact on the behavior of integral bridges. Based on the data generated from the parametric study, new limits for the maximum length and skew angle of integral bridges based on displacement-ductility limit state of piles were established. Literature review revealed that live load distribution among girders in integral bridges due to truck loading conditions is as yet unavailable. This study is extended to develop new equations to estimate girder live load distribution factors for integral bridges. First, 2D and 3D finite-element models (FEMs) of integral bridges were developed. Then, a parametric study was performed to study the effects of parameters such as abutment height, abutment thickness, wingwall length, wingwall orientation, number of design lanes, span length, girder spacing and number of intermediate diaphragms. The results indicated that the live load distribution factors obtained from the FEMs were lower than those obtained from current CHBDC equations. Consequently, sets of empirical expressions were developed in the form of reduction factors that can be applied to CHBDC live load distribution factors to accurately calculate the girder distribution factors. Also, other set of equations for the live load distribution factors were developed in a similar form as that specified in CHBDC for possible inclusion in the bridge code.

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.

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.

Live Load Distribution in Prestressed Concrete Girder Bridges with Curved Slab

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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