Dynamic Performance of Vehicle-Longitudinally Connected Track-Bridge System Under Different Temperature Stress Mitigation Measures

The effects of temperature stress mitigation measures on dynamic performance of the Vehicle-Track-Bridge (VTB) system remains unclear.A rigid-flexible coupled dynamic model of the VTB system was established and validated by conducting dynamic load tests.Typical control measures include fully weak longitudinal connection (WLC) and semi-WLC as well as vertical and longitudinal unitization measures,their influences on train safety,comfort and structural dynamic response were evaluated.Under the WLC measure,reducing the joints’ elastic modulus could decrease the wheel load reduction rate and the vertical acceleration of the vehicle body,but it leads to an increase in the wheel-rail contact force and the vertical acceleration of track slab.The wheel-rail contact force and the vertical acceleration of the track slab under the semi-WLC measure are significantly lower than those under the full WLC.Compared with the lower elastic molds,the WLC measures of high elastic molds are more conducive to the dynamic stability of the system.Under the vertical unitization measure,the increase in the unlocking depth significantly enhances the vertical acceleration of the vehicle body and the lateral displacement of the track slab.The dynamic response under the full unitization measure is much greater than that under the local unitization measure.The vertical unitization of unlocking wide-narrow joints and mortar layers,combined with the longitudinal unitization measure of adjacent three track slabs into one unit,is the optimal control measure for the dynamic performance of the system.