| dc.description.abstract | Uganda has several historic bridges from the mid-twentieth century, but there is a significant
demand for new bridges in many other places to meet future traffic demands. The report case study
is located on a highway in Western Uganda, a region that has experienced several earthquakes.
The installation of devices such as dampers in bridges, as designed in our case study, is one option
for mitigating seismic effects; however, construction has been halted.
The major goal of this research was to assess the influence of seismic dampers. We used Midas
Civil, a finite element software to model, analyse, and compare the influence of dampers in bridge
design. The two-span steel girder composite bridge was subjected to a seismic action of (PGA =
0.1g), on ground type B, with the respective horizontal elastic response spectrum acceleration
curve according to EC8.
Several indices including fundamental period, base shear, and nodal displacements, were used to
assess the bridge's seismic performance. The required number of modes was 8 modes in modal
analysis to attain a total participation mass of 90%. The base shear and nodal displacement
decreased with the addition of a damper. A maximum reduction of 11.86% and 39.68% was seen
for base shear and nodal displacements respectively.
Based on extensive analytical modelling, Finite Element (FE) analysis, the following conclusions
could be made:
i) Seismic performance of a bridge improves by installing energy-dissipating devices
(dampers) as they absorb and dissipate energy during an earthquake, base shear reduces
effectively and the accelerations decrease, implying reduced inertial forces.
ii) Increase in the thickness of the pier section helps to reduce the displacement response
of the bridge. However, increments in the section beyond a certain point cause an
increase in the response in the longitudinal direction and in addition of the bridge pier
becomes very uneconomical
iii) The reduction in the displacement response due to the increase in the pier section
(6.9%) is much less than the reduction in displacement response due to the addition of
dampers (39.6%). However, the latter proves to be a more cost-effective alternative as
compared to the use of Viscous Dampers in the Seismic design of the bridge. | en_US |
