Cable-stayed bridges - Computational Analysis and Design of Bridge Structures - page 364

The girder is restrained in both vertical and lateral directions with towers
in all three cases. Under longitudinal wind loads, displacement at the top
of the tower is 1052 mm (41.4″), and girder displacement is 988 mm
(38.9″) if there is no longitudinal restraint at all. In the lateral direction,
the maximum tower displacement is 276 mm (10.9″ in the maximum
dual-cantilever stage).
Six load patterns are studied to search for load safety factors in the sta-
bility analyses:
1. In the complete stage, maintain dead loads and cable jacking loads and
increase vehicle loads. At 40 times, displacements abruptly reached 42
(138′) and 13 m (42.7′) in the middle of the main span and the top of
the pylons, respectively.
2. In the complete stage, maintain cable jacking loads and increase dead
loads. At three times, displacements abruptly increased.
3. In the maximum dual-cantilever stage, maintain dead loads and cable
jacking loads and increase construction loads. At 240 times, displace-
ments abruptly increased.
4. In the maximum dual-cantilever stage, maintain dead loads and
cable jacking loads and increase lateral wind loads. The bridge still
remains stable when the lateral loads are increased by 50 times and
the lateral displacement at the end of the girder reaches to 7 m (23′)
accordingly.
5. In the maximum single-cantilever stage, maintain dead loads, cable
jacking loads, and lateral wind loads and increase construction loads.
At 46 times, vertical displacement at the end of the girder increased
to over 100 m (328′), accompanied with 42 m (138′) of lateral
displacement.
6. In the maximum single-cantilever stage, maintain dead loads and
cable jacking loads and increase lateral wind loads. At 48 times, the
lateral displacement at the end of the girder increased over 100 m
(328′).
In all six patterns, only the construction load, which includes a 1000 kN
(225 kip) crane at the end of the girder and a uniform load of 10 kN/m
(0.685 kip/ft) in the maximum single-cantilever stage (5), shows the cou-
pling of bending in vertical and lateral directions. Figure 11.33 shows the
displacements in load pattern 5. The stability analysis also shows that the
bridge is more vulnerable before closure in the main span than before reach-
ing the second auxiliary pier in the side span. Although results of these six
loading patterns show that the bridge has sufficient stability against live,
wind, construction, and dead loads, full nonlinear ultimate analysis, in
which material nonlinearity is also considered, and aerodynamic stability
analysis are required.