Road network is still the primary transportation
system in Nepal, and bridges are the most sensitive part of that system. Most
of the bridges were constructed about 40-50 years ago based on the design life
of 50 years and traffic forecast for 30 years. The design was based on an allowable
stress method where a small value of seismic design force was considered. Therefore,
it is necessary to evaluate the seismic performance for the continuous use of
an existing bridge. The structure was evaluated separately for the allowable
stress method and ultimate capacity method as per the revised code. The seismic performance of the bridge was then estimated with the Capacity
Spectrum Method and the Response History Analysis. These analyses imply that
the structure has enough capacity to meet the seismic demand as per the revised
code or when the double lane standard deck replaces the existing one. However,
the failure mode is a shear failure, so retrofitting should be done for the continuous
use of an existing structure.
Keywords:
Allowable stress, Ultimate capacity design, Steel jacketing, Non-linear earthquake responses.