Dynamic Anaiysis of Suspension Bridge

Any pedestrian who has crossed a suspension bridge will agree to the fact that it will
move. The motion of the bridge represents the dynamic response. Typically, researchers
use a combination of both analytical and experimental methods, coupled with system
identification technique. However, only analytical method was implemented in this
project. The suspension bridge was modeled as a fixed-fixed beam, while ignoring the
effects of the hangers, bridge pylons and cable backstays. A single walking person is
modeled as a single point load moving across the beam with constant speed. The critical
speeds of the beam were also determined. Four different moving speeds were used.
Maximum deflection of the beam occurs when the location of the load coincides with
that particular node. But at speeds near critical speeds, the maximum beam deflections
do not occur at location of the load. Also, the maximum deflection undergone by a node
does not occur when the load coincides with that particular node.
In future, some of the simplifications done such as ignoring should be omitted in order
to produce more accurate results. A wider range of speeds should be used to further
explore the effects and to determine if there is any predictable pattern of deflections in
the beam model. In addition to that, the forces generated from walking should be offset
to left and right of the middle of the beam or deck to imitate the alternating footsteps of
a walking person. A 3D model can be created in order to study the torsional and lateral
vibrations of the bridge. It can even be used to study combined vibration modes.