Cable-stayed bridges - Computational Analysis and Design of Bridge Structures - page 352

Figure 11.22 Cable-stay damping systems in Arthur Ravenel Jr. Bridge.
11.3 ConstruCtion Control
The unique construction method of cable-stayed bridges brings up a dis-
tinctive topic to cable-stayed bridges—construction control. The girder is
erected segment by segment, and the cables are jacked pair by pair during
erection. Engineering errors commonly exist in any step of this long pro-
cess, and as a result, what engineers expect may not be achieved at the end.
Among many structural measurements of a bridge state, girder geometry
and cable forces are the two most critical ones. Too many errors in girder
geometry may cause the closure segment hard to fit and adjust, and too
many errors in cable forces may cause cable forces to exceed their allow-
able range. The importance of reducing these errors is obvious. Engineering
error does exist in any bridge construction. The control of engineering
errors is important especially in cable-stayed bridges.
11.3.1 observation errors
There are two types of errors: (1) observation errors and (2) construction
errors. The observation errors are due to the measurement systems, which
occur in measuring the following characteristics:
1. Girder elevations
2. Cable stresses or forces
3. Horizontal displacement at the top of pylons
4. Stresses on the bottom of pylons
5. Stresses on the top and bottom of the girder at any point of interest
6. Environmental temperature, and so on