Transverse load distribution of skew cast-in-place concrete multicell box - girder bridges subjected to traffic condition

Iman Mohseni,A Khalim Rashid

doi:10.1590/s1679-78252013000200002

Iman Mohseni, A Khalim Rashid

Open Access

https://doi.org/10.1590/s1679-78252013000200002

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Abstract

Concrete multicell box-girder bridges are a common choice among the designers for various ranges of bridges. In order to provide safer and greater speed of traffic, the roadway is built as straight as possible. The use of skewed bridges has increased considerably in the recent years for roadway. The skewed bridges have quite different mechanical behavior from the straight bridges, although for skew angles less than 20 degrees, it is reasonably safe to ignore the effect of skew angles and analyze that at the straight bridge. In this study, in developing an analytical solution, an extensive parametric study was carried out to determine the maximum positive and negative stress distribution factors and to calculate the maximum distribution factor of deflection along the mid-span of skewed multicell box-girder bridges. A total of 240 representative bridges numerical models were selected and analyzed using SAP2000 finite element software. It was found that the span length, number of boxes, number of lanes and skew angles significantly affected the distribution factors of stress and deflection. Finally, several equations were proposed for stress and deflection distribution factors of multicell box-girder bridges for the application of American Association of State Highway and Transportation officials load and resistance factor design live loads.

Highlights

Concrete multicell box-girder bridges (MCB) are the most common type of highway bridges (Song et al, 2003)
Advanced computer techniques can determine the effect of vehicle loads (Lin and Weng, 2004) and distribution of live loads in concrete bridges, until recently, the original “s-over” equations in the American Association of State Highway and Transportation officials (AASHTO, 2002) are used for the calculation of live load distribution factor of skewed bridges
Based on the results of an extensive parametric study on continuous skewed multicell box-girder bridges the following conclusions and recommendations were drawn: 1. The three–dimensional finite element modeling by SAP 2000 is appropriate for evaluating the behavior of skewed bridges

Summary

Introduction

Concrete multicell box-girder bridges (MCB) are the most common type of highway bridges (Song et al, 2003). These bridges have excellent torsional and stiffness, equipped with elegance. The “s-over” equations are developed for straight bridges and the effects of skew angle and continuity are not included in this code. Such simplification leads to very conservative results for long span bridges, and to unsafe results for short span bridges (Huang et al, 2004; Huo and Zhang, 2008; Sotelino et al, 2004). Ebeido and Kennedy (Ebeido and Kennedy, 1996) observed that as skew angle was less than 30 degrees, neglecting the effect of skew angle was considered

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