The National Academies Press

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From page 8... ... Selected speciﬁcations articles are as follows: • Article 4.6.1.2.2, "Single-Girder Torsionally Stiff Superstructures," allows for the analysis of horizontally curved, torsionally stiff single-girder superstructures for global force effects as a curved spine beam. • Article 4.6.1.2.3, "Multicell Concrete Box-Girders," allows for the design of horizontally curved cast-in-place multicell box-girders as single-spine beams with straight segments, for central angles up to 34°within one span, unless concerns about force effects dictate otherwise. Read the entire page →
From page 9... ... It includes the requirement to consider the effects of curvature, skew, rotations, and support restraint. The commentary includes additional discussion pertinent to curved bridges. Read the entire page →
From page 10... ... There is a mention of a stress limit for the principal tension at the neutral axis of the section but the specific code section was not referenced. Article 5.8.5 provides limits on the principal tensile stress in the webs of segmental concrete bridges at the Service III limit state and during construction. Read the entire page →
From page 11... ... be – effective width of shear ﬂow path, but not exceeding the minimum thickness of the webs or ﬂanges comprising the closed box section.(in.) be shall be adjusted to account for the presence of ducts as speciﬁed in Article 5.8.6.1. Read the entire page →
From page 12... ... ≤ 2.0 (Equation 5.8.6.3-3) fpc = Unfactored compressive stress in concrete after prestress losses have occurred either at the centroid of the cross section resisting transient loads or at the junction of the web and ﬂange when the centroid lies in the ﬂange. Read the entire page →
From page 13... ... , "Web Design for Shear and Transverse Bending," presents a rational method for the design of webs subject to combined shear and regional transverse bending, a condition that occurs in horizontally curved post-tensioned box-girder bridges. The method is based on Swiss practice and neglects the concrete contribution to the shear capacity. Read the entire page →
From page 14... ... A simple table of equations based on classical curved beam theory is presented for several different loading conditions of a curved singlespan bridge with ﬁxed supports. The "Dimensioning and Detailing" section covers several aspects of curved bridges. Read the entire page →
From page 15... ... 799–819. A discrete strip energy method is presented for the analysis of curved box-girder bridges of arbitrary cross section and various forms of curved folded plate structures simply supported at the two ends and composed of elements that may, in general, be segments of conical frustra. Read the entire page →
From page 16... ... 2481–2501. A finite element method for the analysis of simply supported curved girder bridges with horizontal sector plates and vertical cylindrical shell elements is outlined. Read the entire page →
From page 17... ... The report outlines the methods developed over the years for analyzing curved bridges. These include straight beam approximation, curved beam theory, reﬁned curved beam theories, plate and grillage analysis methods, ﬁnite element analysis, and the ﬁnite strip method analysis of curved folded plates. Read the entire page →
From page 18... ... Finite Strip Method 5. Finite Element Method The orthotropic plate method lumps the stiffness of the deck, webs, sofﬁt, and diaphragms into an equivalent orthotropic plate. Read the entire page →
From page 19... ... 2459–2480. A ﬁnite strip method of analysis is presented which can be used to analyze curved folded plate structures simply supported at the two ends and composed of elements that may, in general, be segments of conical frustra. Read the entire page →
From page 20... ... (1972) "Multicell Curved Girder Model Studies," Journal of the Structural Division, Vol. Read the entire page →
From page 21... ... Design Issues Bearings Although several bearing failures consisting of uplift, overload, or binding have been experienced in curved box-girder bridges, no published research exclusively addressing this issue was found. However, because an accurate 3-D analysis will account for differences in bearing forces and displacements, several references that deal with global analysis and laboratory experimentation deal with this issue (Aslam and Godden, 1975; Scordelis et al., 1977; Choudhury and Scordelis, 1988; Sennah and Kennedy, 2002) Read the entire page →
From page 22... ... At a cross section where negative shear lag is signiﬁcant, the bending stress away from the webs is greater than the stress near the webs. This paper is only indirectly applicable to this project because the paper does not deal speciﬁcally with curved girders. Read the entire page →
From page 23... ... The values of effective width ratio of the present theory are lower than the folded plate theory curves, and the inside and outside effective width ratio agree with the values of the straight beams, irrespective of crosssectional shapes or types of load distributions. The authors analyze the inner and outer effective widths at mid span relative to the curvature R/L. Read the entire page →
From page 24... ... Fu, Chung C, and Yang, Dailli (1996) "Designs of Concrete Bridges with Multiple Box Cells due to Torsion Using Softened Truss Model" ACI Structural Journal, Vol. Read the entire page →
From page 25... ... developed for modeling bridge superstructure with straight or skewed supports and obtaining live load distribution factors. Although this computer program did not consider curved geometry speciﬁcally, the modeling process and load placement guidelines may be used for analysis of curved bridges as well. Read the entire page →
From page 26... ... 26 Figure 3-1. Caltrans detail A Read the entire page →
From page 27... ... The vertical reinforcement in the web is subjected to combined global shear and regional transverse bending due to regional beam action. No specific design methodology for these combined actions is given by AASHTO. Read the entire page →
From page 28... ... (1993) Time-Dependent Analysis of Nonprismatic Curved PC Box-Girder Bridges, 28 Read the entire page →
From page 29... ... It is concluded that the ﬁnite strip method offers an accurate and inexpensive tool for the optimization of box-girder bridges having regular prismatic-type geometry with diaphragm ends and in curved planform. Detailing The detailing of prestressed concrete in bridges is addressed by several agencies that commonly use this structural form. Read the entire page →
From page 30... ... Sophisticated elastic analysis techniques such as ﬁnite element methods have been shown to produce excellent results that compare well with physical testing. It is therefore not necessary to do any more sophisticated research on this subject. Read the entire page →

From page 8...

... Selected speciﬁcations articles are as follows: • Article 4.6.1.2.2, "Single-Girder Torsionally Stiff Superstructures," allows for the analysis of horizontally curved, torsionally stiff single-girder superstructures for global force effects as a curved spine beam. • Article 4.6.1.2.3, "Multicell Concrete Box-Girders," allows for the design of horizontally curved cast-in-place multicell box-girders as single-spine beams with straight segments, for central angles up to 34°within one span, unless concerns about force effects dictate otherwise.