The Moving Load Problem in Structural Dynamics

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CHAPTER 1
INTRODUCTION
The moving load problem is a fundamental problem in structural dynamics. Engineers have been investing the potential hazard produced by the moving masses on structures for many several years. The dynamic response of structures carrying moving masses is a problem of widespread practical significance. A lot of hard work has been accounted during the last ten decades relating with the dynamic response of railway bridges and later on highway bridges under the effect of moving loads. Beam type structures are widely used in many branches of civil, mechanical and aerospace engineering. The importance of moving mass is found in several applications in the field of transportation. Railway and highway bridges, suspension bridges, guide ways, crane runways, cableways, rails, roadways, runways, tunnels and pipelines are example of structural elements to be designed to support moving masses. Also, in the design of machining processes, many members can be modeled as beams acted upon by moving loads.
The dynamic effect of moving loads was not known until mid-nineteenth century. When the Stephenson’s bridge across river Dee Chester in England in 1947 collapsed, it motivates the engineers for research of moving load problem. Moving loads have a great effect on the bodies or structures over which it travels. It causes them to vibrate intensively, especially at high velocities. The peculiar features of moving loads are they are variable in both space and time.
Modern means of transport are ever faster and heavier, while the structures over which they move are ever more slender and lighter. That is why the dynamic stresses they produce are larger by far than the static ones.
The majority of the engineering structures are subjec...

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...s insufficient. It brings out more accurate results to take into account the mass and velocity of the moving load and dynamic properties of carrying system in dynamic analysis.
3. The effect of the change of material on the dynamic response on both simply supported and cantilever beam is same.

SCOPE OF FUTURE WORK:
1. The present research can be extended to Timoshenko beam.
2. Acceleration of a travelling mass over a structural system, highly affects the dynamic response of the structural system. It can give engineers some advantages to make a more realistic modeling of structural systems under accelerating mass motion than classical methods that omit inertial effects of accelerating mass.
3. There are situations when a series of moving mass travels over a beam as a train travels over a bridge. Response of beams to such types of moving load is research worthy.

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