Research On Dynamic Behavious Of The Prestressed Concrete Beam Bridge Under Moving Vehicle Load

The dynamic behaviour of prestressed force on the preventing the crack development, and the increasing the dynamic stiffness and durableness of the structures is effective.The high strength capability of material and the prominent societal and economic benefit are brough.So prestressed concrete structures are applied widely to all kinds of engineering structures.The vibration of bridge structure under moving loads is one important factor for normally use and the security. The effect of dynamical impulsion (dynamical coefficient) under moving loads like vehicles must be considered for design and calculation of the bridge and especially for long span prestressed bridge.In this paper, the prestressed concrete simple-beam bridge is studied, and the basic concepts and the states of stress of in the prestressed concrete beam bridge and investigative status of the dynamical effects between vehicles and bridge are introduced, then the developable tendency of dynamics of bridge is pointed. Based on the influence of the axial force on the transversal vibration of prestressed bridge, the dynamic equations are established by considering the different arrangement pattern of prestressed reinforcements. The formulas of the natural frequency of the prestressed beam, considering the different arrangement pattern of prestressed reinforcements, are obtained by force method.The key influential factors on the natural frequency of the beam are presented.By considering the moving vehicles loads as a single moving force, and assuming the perfect joint between wheel and bridge road surface is perfect in the paper, the differential equations of forced vibration of the prestressed concrete beam are obtained. The approximative expressions of dynamical deflection, velocity and acceleration of the prestressed beam are presented. The dynamical deflection, velocity and acceleration curves of the prestressed beam under moving loads at various speeds are obtained, and the comparison between dynamical effects whether considering the prestressed force is revealed by practical example.Considering the influence of geometric nonlinears and transversal shear deformation, the basical dynamic equations of forced vibration of the beam are established. The transversal vibration behaviors of the prestressed concrete beam are analyzed and calculated. Applying the incremental harmonic balance method, the dynamical response of the prestressed beam under moving loads is obtained by the linearization of nonlinear equations.The amplitude-frequency dynamical response curves and the nonlinear ralation between dynamic displacements and moving loads. The basic theory for analysis of dynamic behaviors and design of the prestressed concrete bridge is presented.