Suspension bridges - Computational Analysis and Design of Bridge Structures - page 374

Step 1—Build pylons and anchorage blocks
Step 2—Build catwalks and erect main cables
Step 3—Erect stiffened girders
Step 4—Erect the last girder segments
Step 5—Rigidly connect girder segments
Figure 12.5 Construction process of a suspension bridge (showing from tower to installing
stiffened girder).
not balanced, and the pylons will be deflected toward the main span. For
these flexible pylons, saddles on the top of pylons have to be adjusted so as
to release most deflection of pylons due to dead loads.
Anchors are the components that distribute the cable forces to ground
so that the main cables are sustained. The main cables in most suspension
bridges are anchored externally. The anchors of these bridges can be clas-
sified as gravity anchor and rock tunnel anchor. The gravity anchor is built
by massive concrete to balance the cable forces. Where the geology is per-
mitting, an inclined tunnel can be excavated down to the bedrocks and the
anchor beams or bars can be built into ground with backfilled concrete.
Steel wires of the main cable will have to be sprayed out by going through
a splay saddle in front of the anchorage so as to be anchored wire by wire or
to group several wires together. One main function of the splay saddle is to
change the cable tangent more downward so as to make the anchorage easy.
The change of the cable tangent at the end will also reduce the anchor forces
directly to the anchorage as part of the cable forces will be distributed to
splay saddle. In terms of the bending in the main cable plane, the splay saddle
can be rigid or flexible. Figure 12.6 shows a typical rigid splay saddle that is