As I have showcased irresponsibility and forgotten my flash drive, this post will serve for my notes today. At least it proves I was working. Check this out:

http://www.structuremag.org/article.aspx?articleid=768
Evolution of the Cable-stayed bridge

Construction technology and material science for bridges have been an important part of advancing cable stayed bridge technology. Material advancements introduced into bridge applications include self-consolidating concrete, stainless steel, higher strength concretes and composite fibers.
           - Gives overview of 9 different cable-stayed bridges, both radial and parallel design. Bridges chosen for some design element they made use of.

Experience from these completed cable-stayed bridges has shown that the torsional rigidity of a closed cell box girder superstructure enhances structural response to wind loading during construction and eliminates the need for temporary stabilization attachments. Unique features such as precast delta frames and struts can expand the box girder to a system that allows the use of single pylons with a single plane of stays. This pre-fabrication and streamlined approach to long spans contributes to quicker construction. The cable-stayed system of continuous strands, with anchors only at deck level, creates easy access to the stays inside the box girder superstructure for both construction and future inspection. In addition to the economical use of cable-stayed bridges for spans of 600 feet to 1,500 feet and greater, the configurations offer an elegance that also addresses communities’ interests in creating exciting landmark bridges for the future.

Book to buy - don't buy, can see it all in the preview

Cable Stayed, Supported And Suspension Bridges

By P. Dayaratnam


http://freeit.free.fr/Bridge%20Engineering%20HandBook/ch19.pdf

THE MOST BEAUTIFUL LINK EVER.
Seriously. Explains everything about cable-stayed bridges, in different spans, from and engineer's bridge handbook. Will take a while to read though. Notes to follow:

For spans up to about 1000 m, cable-stayed bridges are more economical.

A bridge carries mainly vertical loads acting on

the girder,

Figure 19.1. The stay cables provide intermediate supports for the girder so that it can

span a long distance. The basic structural form of a cable-stayed bridge is a series of overlapping

triangles comprising the pylon, or the tower, the cables, and the girder. All these members are under

predominantly axial forces, with the cables under tension and both the pylon and the girder under

compression. Axially loaded members are generally more efficient than flexural members. This

contributes to the economy of a cable-stayed bridge.


quick link interjections, to explain other terms: Axial v. flexural stress
http://arch.umd.edu/Tech/Tech_III/Lectures/Flexure/Principles_of_Flexure.pdf
http://www.areforum.org/forums/showthread.php?132647-Axial-vs-Flexural-stress

At the early stage, the idea of a cable-stayed bridge was to use cable suspension to replace the piers

as intermediate supports for the girder so that it could span a longer distance.

The bending moment in the girder under a specific load can be thought of as consisting of

a local component and a global component. The local bending moment between the cables is

proportional to the square of the spacing. The global bending moment of an elastically supported

girder is approximately

- look up global bending moment - http://web.aeromech.usyd.edu.au/AMME2301/Documents/mos/Chapter05.pdf
http://www.cee.lsu.edu/people/cai/J1998-Composite%20Girder%20Design%20of%20Cable-Stayed%20Bridges.pdf

Considering that the function of the cables is to carry the loads on the bridge girder, which

remains the same, the total quantity of cables required for a bridge is practically the same independent

of the number of cables, or cable spacing,

Figure 19.4. But if the cable spacing is smaller, the

local bending moment of the girder between the cables is also smaller. A reduction of the local

bending moment allows the girder to be more flexible. A more flexible girder attracts in turn less

global moment. Consequently, a very flexible girder can be used with closely spaced cables in many

modern cable-stayed bridges.

Harp, radial, fan,

Figure 19.7, or other cable configurations have all been used. However, except

in very long span structures, cable configuration does not have a major effect on the behavior of

the bridge.


I only mangaged to get 1.5 sections into 7, but this hopefully will explain the basic mechanics of cable-stayed bridges so that I can apply them to the Margaret Hunt Hill Bridge.