Analysis On Dynamic Response Of Long-Span Cable-Stayed Bridge Steel Deck Pavement

Cracking deterioration has become the main problem in deck pavement of long-span cable-stayed bridge under the dynamic vehicle load. The result of the static analysis of deck pavement can not exactly illuminate the crack failure of deck pavement, so the dynamic response of deck pavement under dynamic vehicle load was researched in this paper to explain the cracking deterioration better.Firstly, finite element software was used to establish the orthotropic steel deck pavement model which is usually used in long-span cable-stayed bridge. Through the Modality analysis, the vibration characteristics were researched, and the influence of the thickness and modulus of pavement on Natural Frequency of the model was discussed.Secondly, by using time function and time step, the vehicle load was set to be wheel load which has the invariable value, and the impact coefficient was considered only in the load. The result of dynamic analysis shows that the middle place of the model is the worst place, whereas the vertical displacement and the transverse maximum tensile stress would come to its peak value in the worst place. The change of the vehicles'speed together with the change of the damp slightly affects the result. The value of the vertical displacement and the transverse maximum tensile stress will decrease when increasing the speed of the vehicles or the damping ratio.At last, the irregularity of the pavement's surface was simulated by using the power spectrum density function and the random load was calculated according to the vehicle vibrating equation, the dynamic response of deck pavement under random dynamic load was calculated by using FEM. The result of dynamic analysis shows that the vertical displacement is 1.35 times as much as the vertical displacement when the impact coefficient is taken into account only, and the transverse maximum tensile stress is 1.34 times as much as the transverse maximum tensile stress when the impact coefficient is taken into account only. The increase of the dynamic response of pavement considering the irregularity is bigger than the dynamic response of pavement considering the impact coefficient only. The result puts a higher request in the pavement construction and maintenance, and also presents that it is not enough to consider the impact coefficient only in the vehicle load.The conclusions of this dissertation can provide kinetics parameters for the method of stress/strain equivalence of fatigue experiment and theoretical reference for the analysis of the material and structure of deck pavement.