Cable-stayed bridges - Computational Analysis and Design of Bridge Structures - page 338

More significant bending moments
than a continuous girder (a) Moment distributions

Low cable stresses

(b) Axial force distributions

(c)

Displacements More significant deflections than a continuous girder

Figure 11.15 (a-c) Weak supports from cables.

both the girder and the pylons are more efficient under axial compression
than under tension and compression due to large bending moments.
For any particular cable-stayed bridge, such an ideal state of dead load
distribution will also depend on the pylons. Sometimes, when girder spans
are not symmetrical around a pylon and most of girder dead loads are
transferred to the pylon as well, certain moment will be created at the
bottom of the pylon as shown in Figure 11.16. The girder moments, the
horizontal displacements at the top of the pylons, and the longitudinal
bending moments at the bottom of the pylons are usually the primary con-
trol points to determine an ideal state. It should be noted that the so-called
ideal state, as shown in Figure 11.16, is only to demonstrate that dead loads
on the girder should be redistributed to pylons by adjusting the jacking
forces of cables. In more real situations, such an ideal state is unsuitable,