Study On Structural Behavior Of Track-ballast-beam System

The working conditions and safety of existing railway bridges cause people more attention,for the Chinese railway bridges aging is more and more serious. It is important to evaluate and inspect the existing railway bridges.The load of railway bridges is transferred by track and ballast.During the evaluations of existing bridges,it is necessary to analyze the integral forced performance of track-ballast-beam body in order to ensure the accuracy on analyzing the bridge forced conditions.During the bridge state inspections the field loading test is relatively precise.It has an important effect to select one suitable data processing method,because massive data is recorded in the field loading test.In this paper bridge dynamic testing data is processed by the rain-flow counting method.The data processing specific program is compiled to enrich the bridge evaluation methods.In the paper,large finite element software is used to build the integral forced model of track-ballast-beam body,to simulate the true forced state.The ballast is simulated by springs in the model,so the load vertical transferring effects can be studied though changing spring stiffness.The changing regulations of track-ballast-beam system are summarized as the ballast stiffness changing.In order to analyze the effects of live load transferring,which is applied on the multiple-span track-ballast-beam body simple beam,it is necessary to build the simple beam models which have the different number of spans.In the paper it is proved that track and ballast have obviously load distribution effect as a composite forced system.The strain of beam body is obviously smaller based on forced system than based on nude beam.The stress and deformation become gradually smaller as the ballast stiffness becomes bigger.The Mid-span load transferred to adjacent spans is more,which proportion is about twenty percent.The sharing proportion is increased with the ballast increasing.