Abstract
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.
Highlights
Traditional bridge structures use expansion joint systems to accommodate the change in the bridge length that is induced by changes in the temperature of the bridge superstructure
Based on the results obtained from the parametric study conducted on selected integral abutment bridge configurations subjected to seasonal temperature variations and Canadian Highway Bridge Design code (CHBDC) truck loading, the following conclusions can be drawn: 1- The effect of the orientation of the steel H-piles on the pile displacement of integral bridges with stub abutments is negligible. 2- A concrete bridge has longer allowable total length than that for a steel bridge as the former is less sensitive to seasonal temperature variations
21- First set of empirical expressions were developed in the form of correction factors which can be apply to the CHBDC live load distribution equations for slab-on-girder bridges to obtain a reliable and better estimation of the girder moments and exterior girder shear force of single-span integral abutment bridges
Summary
Traditional bridge structures use expansion joint systems to accommodate the change in the bridge length that is induced by changes in the temperature of the bridge superstructure. Performance deficiency of many expansion joints and other structural release mechanism systems in traditional bridges is a big issue. These joints fail in one or more important aspects, notably water-tigthness when they subject to traffic and bridge movement. They often leak and allow water contaminated with salt and debris which spilled onto substructure and underside of the deck. The concept of integral abutment bridge was developed in an attempt to eliminate joints in these locations
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