Details:

Creators:
Gull, Jawad H. ; Azizinamini, Atorod
Gull, Jawad H. ; Azizinamini, Atorod Less -
Corporate Creators:
Florida International University
Subject/TRT Terms:
[+]
Braces Bridge Design Diaphragms (Engineering) Finite Element Method Plate Girders Steel Bridges Stiffness Structural Connection Traffic Loads
Publication/ Report Number:
BDK80-977-20
Resource Type:
Tech Report
Geographical Coverage:
Florida
Corporate Publisher:
Florida. Dept. of Transportation
Abstract:
The wide spectrum of options available to designers for analyzing and determining cross-frame forces can be a

source of problems because different options may not result in similar solutions. The main objective of this

project was to develop a set of recommendations and procedures and instructions to address analysis, design, and

construction issues related to braces in steel I-girder bridges.

Different methods that can be used to calculate brace loads are categorized and discussed in detail to identify the

strengths and limitations of each method. The traditional 2D-grid analyses that are often used by commercial

software packages ( such as MDX and DESCUS) does not take into account the full warping stiffness, resulting in

underestimation of torsional stiffness of the girders. Although improved 2D-grid analyses may result in an

improved representation of the full warping stiffness, these models are generally applicable to a no-load fit

condition for cross-frames or diaphragms. The procedure by which 2D-grid analyses can be used for calculating

cross-frame forces and other structural responses of bridges detailed with dead load detailing methods (erected fit

and final fit) are described. It has been found that performance of improved and traditional 2D-grid analyses also

depends on the framing layout (contiguous or staggered). Improved 2D-grid analyses are preferred for calculating

the cross-frame forces because of the satisfactory performance for most of the framing layouts. A relatively

simple method of simulating lack-of-fit is introduced in this report which makes use of models using three-dimensional (3D) finite element method (FEM). Although past studies have recommended using initial strain to

simulate lack-of-fit in the cross-frames, this method can be tedious and complex. The proposed method makes

use of element birth and death techniques to activate or deactivate the cross-frame elements to obtain a measure of

the force or deformation at specific desired stages. The element birth and death method is generally more simple

than the initial-strain methods with the essentially the same level of accuracy. Finally, different options for

framing layouts, detailing methods, cross-frame configurations, and design methods for sizing the cross-frame

members are discussed.


Format:
PDF
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:03d65c917b048f5c67056dd5ef7b5f7c282fa8f90c64d207d25072559c266f03
Download URL:
https://rosap.ntl.bts.gov/view/dot/27738/dot_27738_DS1.pdf
File Type:

Supporting Files

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