Abstract:
Padma Multipurpose Bridge (PMB) is one of the most important projects in the
history of Bangladesh due to its regional importance, economic benefit, and
primary connectivity of one-third population of the country. The bridge is
6.15km long, connecting the ends of Mawa and Janjira in Bangladesh. The entire
project is challenging to construct and complex in design as it contains both
four-lane highways and train tracks supported by a double-deck composite
warren truss. In this study, the dynamic response of the truss due to the moving
train has been analyzed using the Moving Element Method (MEM). In this
process, a separate finite element model has been developed using Finite
Element (FE) program to convert the double deck truss into an equivalent
beam. Analysis has been conducted for a series of different load cases,
converging to the most realistic case where the actual train parameters are
considered. Parametric studies have been carried out to determine the dynamic
responses of the bridge with varying pier spacing and speed of the train. The
most optimal solution has been discussed with the effect of the vibration of the
train acting on the multi-purpose Padma bridge. The bridge's dynamic
amplification factor (DAF) at a design speed of below 100km/hr is found 1.05.
The parametric study shows that the critical train speed for the PMB is
1400km/hr resulting in the bridge resonance with a DAF of 18. It is also evident
that with the increase of pier spacing the resonance of the bridge is expected to
occur at a relatively lower speed.
