Abstract:
ABSTRACT
The study deals with static, dynamic (earthquake response)
analysis, and seismic analysis of cable stayed bridges. The analyses
include the effect of using damping systems on the response of bridge
to various directions of earthquakes.
The bridge of semi-fan type cables is considered in this study.
Detailed analysis aspects of modeling, loading, boundary conditions
(deck as simply supported beam and towers were fixed at base in all
directions), and solution ar
components were idealized as three dimensional modeling with shell,
link and beam elements having six degree of freedoms. The cables are
modeled in two schemes; First scheme as single link element, and
second scheme as multi- beam elements.
Gravity load is applied on all nodes of cable stayed bridge.
Accordingly, static and free vibration analyses of the cable stayed
bridge are studied for cases of gravity load. It was found that,
deflections of deck in first scheme were less than 30% those in second
scheme. The results of first scheme were more realistic than those of
The cable stayed bridge is analyzed for earthquake excitations
acting independently in three directions, longitudinal, transversehorizontal
and transverse- vertical directions. It was found that
earthquakes in transverse- horizontal direction have greater effects on
50% than earthquakes in other directions
because of its danger to the collapse of towers.
Damping effects on reduction deflections, resulted from
earthquakes, are studied. The effect of changing number, direction and
value of damping coefficient on reduction response to earthquake, are
analyzed. Results show that inclined dampers were more effective than
vertical dampers in longitudinal and lateral earthquakes. Damping
effect of eight inclined dampers was 80% in deck deflections at lateral
earthquake component. four vertical dampers have damping effect 50%
on deck deflections with lateral earthquake
