Structural Design Issues For Integral Abutment Bridges

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.

Shear Distribution in Curved Composite Multiple Box Girder Bridges

Horizontally curved composite box girder bridges are used in interchanges of modern highway systems. This type of structure has created design problems in estimating its live load. North Americans Codes of Practice recommends some analytical methods for design of such curved bridges. However, practical requirements arising during the design process necessitate a simple design method. On the basis of the literature review, such load distribution factors due to CHBDC truck loading are as yet unavailable. An extensive parametric study, using the finite-element modelling, was conducted, in which 225 prototype bridges were analysed to evaluate their shear distribution factors when subjected to CHBDC truck loading conditions. The parameters considered were number of steel boxes, number of lanes, span length, and span-to-radius curvature ratio. Based on the data generated, empirical expressions for shear distribution factors were deduced. An alternative to the developed expressions were introduced using the Artificial Neural Network (ANN) application.

Investigation of Load Distribution Factors for Simply-Supported Composite Multiple Box Girder Bridges

Composite box-girder bridges are recently used in modern highway urban system because of their profitable and structural aptitude advantages. North Americans Codes of Practice specify empirical equations for girder moment and shear forces in such bridges in the form of live load distribution factors. These factors were proven to be conservative in some cases and underestimate the response in other cases. Therefore, an extensive parametric study, using the finite-element modeling, was conducted to examine the key parameters that influence the load distribution factors of such bridges. A total of 276 prototype bridges were analyzed to evaluate girder bending moment, shear force and deflection distribution factors for simply-supported composite multiple box-girder bridges when subjected to CHBDC truck loading. Design parameters considered in this study were bridges span length, numbers of design lanes, number of box girders and girder spacing. Based on the data generated from parametric study, sets of simple empirical expressions were developed for bending moment; shear force and deflection distribution factors for such bridges. A correlation between the finite-element results with CHBDC and AASHTO-LRFD empirical expressions showed the former are more reliable in structural design of composite box-girder bridges.

Shear Distribution in Curved Composite Multiple Box Girder Bridges

Horizontally curved composite box girder bridges are used in interchanges of modern highway systems. This type of structure has created design problems in estimating its live load. North Americans Codes of Practice recommends some analytical methods for design of such curved bridges. However, practical requirements arising during the design process necessitate a simple design method. On the basis of the literature review, such load distribution factors due to CHBDC truck loading are as yet unavailable. An extensive parametric study, using the finite-element modelling, was conducted, in which 225 prototype bridges were analysed to evaluate their shear distribution factors when subjected to CHBDC truck loading conditions. The parameters considered were number of steel boxes, number of lanes, span length, and span-to-radius curvature ratio. Based on the data generated, empirical expressions for shear distribution factors were deduced. An alternative to the developed expressions were introduced using the Artificial Neural Network (ANN) application.

Load Distribution in Precast Wide-Flange CPCI Girder Bridges

As Ontario bridge infrastructure enters the era of maintenance, rehabilitation and replacement, prefabricated bridge systems will certainly have many advantages as compared to the conventional systems. Prefabricated systems can be quickly assembled and the traffic can be opened in a very short period of time, minimizing the lane closure time, reducing the cost and design time, and minimizing forming and labour work. The Canadian Highway Bridge Design Code specifies simplified design method for slab-on-girder bridges in the form of moment and shear distribution factors. This thesis presents a parametric study, using the finite-element method, on a series of precast Wide-Flange CPCI girder bridges to examine the applicability of the CHBDC load distribution factors to this prefabricated bridge system. The parameters considered in this study include span length, number of lanes, number of girders, live load conditions, presence of intermediate diaphragms, and type of connections between individual girders. This study revealed that CHBDC load distribution factors generally overestimate the structural response of such bridges. As a result, a refined set of load distribution factor equations were developed.

Load Distribution in Precast Wide-Flange CPCI Girder Bridges

As Ontario bridge infrastructure enters the era of maintenance, rehabilitation and replacement, prefabricated bridge systems will certainly have many advantages as compared to the conventional systems. Prefabricated systems can be quickly assembled and the traffic can be opened in a very short period of time, minimizing the lane closure time, reducing the cost and design time, and minimizing forming and labour work. The Canadian Highway Bridge Design Code specifies simplified design method for slab-on-girder bridges in the form of moment and shear distribution factors. This thesis presents a parametric study, using the finite-element method, on a series of precast Wide-Flange CPCI girder bridges to examine the applicability of the CHBDC load distribution factors to this prefabricated bridge system. The parameters considered in this study include span length, number of lanes, number of girders, live load conditions, presence of intermediate diaphragms, and type of connections between individual girders. This study revealed that CHBDC load distribution factors generally overestimate the structural response of such bridges. As a result, a refined set of load distribution factor equations were developed.

Structural Design Issues For Integral Abutment Bridges

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 Load Distribution Factors for Simply-Supported Composite Multiple Box Girder Bridges

Composite box-girder bridges are recently used in modern highway urban system because of their profitable and structural aptitude advantages. North Americans Codes of Practice specify empirical equations for girder moment and shear forces in such bridges in the form of live load distribution factors. These factors were proven to be conservative in some cases and underestimate the response in other cases. Therefore, an extensive parametric study, using the finite-element modeling, was conducted to examine the key parameters that influence the load distribution factors of such bridges. A total of 276 prototype bridges were analyzed to evaluate girder bending moment, shear force and deflection distribution factors for simply-supported composite multiple box-girder bridges when subjected to CHBDC truck loading. Design parameters considered in this study were bridges span length, numbers of design lanes, number of box girders and girder spacing. Based on the data generated from parametric study, sets of simple empirical expressions were developed for bending moment; shear force and deflection distribution factors for such bridges. A correlation between the finite-element results with CHBDC and AASHTO-LRFD empirical expressions showed the former are more reliable in structural design of composite box-girder bridges.

Improved Live Load Distribution Factors for Use in Load Rating of Older Slab and T-Beam Reinforced Concrete Bridges

This report describes a methodology for demand estimate through the improvement of load distribution factors in reinforced concrete flat-slab and T-beam bridges. The proposed distribution factors are supported on three-dimensional (3D) Finite Element (FE) analysis tools. The Conventional Load Rating (CLR) method currently in use by INDOT relies on a two-dimensional (2D) analysis based on beam theory. This approach may overestimate bridge demand as the result of neglecting the presence of parapets and sidewalks present in these bridges. The 3D behavior of a bridge and its response could be better modeled through a 3D computational model by including the participation of all elements. This research aims to investigate the potential effect of railings, parapets, sidewalks, and end-diaphragms on demand evaluation for purposes of rating reinforced concrete flat-slab and T-beam bridges using 3D finite element analysis. The project goal is to improve the current lateral load distribution factor by addressing the limitations resulting from the 2D analysis and ignoring the contribution of non-structural components. Through a parametric study of the slab and T-beam bridges in Indiana, the impact of selected parameters on demand estimates was estimated, and modifications to the current load distribution factors in AASHTO were proposed.